Laser remelting-laser shock in-situ synchronous surface strengthening method for 38CrMoAl alloy steel and application of laser remelting-laser shock in-situ synchronous surface strengthening method

Abstract

The invention discloses a laser remelting-laser shock in-situ synchronous surface strengthening method for 38CrMoAl alloy steel and application of the laser remelting-laser shock in-situ synchronous surface strengthening method, and belongs to the technical field of metal material surface strengthening. The method comprises the following steps that a surface to be strengthened is ground, polished and washed; determining a walking path and adjusting the distance between the remelting laser and the impact laser according to the surface to be strengthened; the method comprises the following steps: remelting the surface of a material under the protection of inert gas, and carrying out in-situ impact on the remelted surface by using pulse laser; according to the strengthened 38CrMoAl alloy steel disclosed by the invention, the average hardness of a strengthened layer is 556-690 HV; the abrasion volume is 0.1375 to 0.3097 mm < 3 >; and the fatigue strength of the alloy is 2017.9 to 2219.4 MPa. Under the combined action of the continuous laser and the pulse laser, the wear resistance of the strengthened layer is remarkably improved, and the wear type is improved.

Description

Technical Field

[0001] This invention belongs to the field of surface strengthening technology of metallic materials, and particularly relates to a laser remelting-laser shock in-situ synchronous surface strengthening method for 38CrMoAl alloy steel and its application. Background Technology

[0002] 38CrMoAl alloy steel is widely used in precision machine tools, aerospace, and chemical industries due to its excellent wear resistance, high fatigue strength, low deformation, and good corrosion resistance. However, because its service environment typically involves high-speed, heavy-load, and long-cycle operation, it is prone to problems such as abrasive wear, adhesive wear, corrosive wear, thermal deformation, and thermal fatigue, which can affect accuracy or even lead to direct failure. Therefore, a strengthening method is needed to extend its service life. Currently, nitriding is a mainstream method for surface strengthening of 38CrMoAl alloy steel, which introduces nitrogen atoms into the surface to form a nitride (such as Fe4N, CrN, AlN) hardened layer. Although this method can improve surface hardness, it can cause thermal deformation of the workpiece under prolonged heat treatment, requiring subsequent finishing. The process is long and complex, and pretreatment of the workpiece is also required before nitriding. If the nitriding process is not properly controlled, a brittle ε-phase white layer will form on the surface, which is prone to peeling off during use, directly leading to equipment failure.

[0003] With the rapid development of lasers in recent years, the industry has proposed a laser remelting surface strengthening method. This method uses a high-energy-density laser beam to rapidly scan and melt an extremely thin surface layer. Subsequently, ultra-rapid solidification occurs due to the enormous heat capacity within the matrix. The huge temperature gradient leads to a sharp increase in the solidification nucleation rate, and the newly formed crystal nuclei do not have enough time to grow, resulting in grain refinement and a high-hardness internal structure, thus strengthening the material surface. While this method has advantages such as small deformation, high efficiency, and strong controllability, its inherent thermal mechanism easily introduces problems such as surface microcracks, microstructure inhomogeneity, residual tensile stress, and insufficient hardness of the hardened layer. These problems often become the source of wear failure in workpieces under long-term operation, severely restricting the reliable application of this technology in critical load-bearing components.

[0004] To address the aforementioned problems with laser remelting, laser shock blasting technology can be introduced for regulation. This technology uses laser-induced plasma explosions to generate high-pressure shock waves far exceeding the material's dynamic yield strength, forcing plastic deformation of the material's surface layer. This introduces deep residual compressive stress and grain refinement, improving the material's mechanical properties. However, existing laser shock blasting processes are mostly post-processing, requiring offline shock blasting after the workpiece has been processed. This results in poor synergy, low efficiency, and low energy utilization. Practical applications are easily constrained by inherent limitations, failing to take advantage of the favorable timing of high-temperature repair layers when yield strength is low and plastic rheological capacity is enhanced, thus missing the opportunity to achieve form-property synergistic regulation under optimal metallurgical conditions. Furthermore, continuous manufacturing is not possible, and shock blasting after the workpiece cools can cause localized thermal effects, leading to unpredictable secondary impacts.

[0005] In summary, traditional single repair methods cannot meet the usage requirements of 38CrMoAl alloy steel workpieces. Currently, there is an urgent need for a surface strengthening method that can rapidly strengthen the surface and provide a good service life after strengthening. Therefore, based on the bottleneck problems of insufficient strengthening performance and inherent process drawbacks of the aforementioned strengthening methods, this invention innovatively proposes a laser remelting-laser shock in-situ synchronous surface strengthening method. Summary of the Invention

[0006] The purpose of this invention is to provide a simultaneous laser remelting-laser shock oscillation in-situ surface strengthening method for 38CrMoAl alloy steel. This method allows for online impact on the material surface during laser remelting, intervening at the optimal metallurgical timing to impact the incompletely cooled high-temperature solid phase region. This increases dislocation slip and promotes heterogeneous nucleation, resulting in a superior microstructure and further grain refinement. It avoids the exothermic reaction during offline impact, which could lead to tempering on the material surface. Furthermore, the impact force can close micro-defects at high temperatures and immediately suppress the initiation of microcracks caused by thermal stress during remelting, while also introducing compressive stress. Therefore, the simultaneous laser remelting-laser shock oscillation in-situ surface strengthening method enables rapid, high-performance, and integrated surface strengthening of 38CrMoAl alloy steel.

[0007] Meanwhile, the purpose of this invention is to provide a reinforced 38CrMoAl alloy steel.

[0008] Meanwhile, the purpose of this invention is to provide an application of reinforced 38CrMoAl alloy steel.

[0009] To achieve the above objectives, the present invention provides the following technical solution: A method for in-situ synchronous surface strengthening of 38CrMoAl alloy steel by laser remelting-laser shock osmosis includes the following steps: Step 1: Grind and polish the 38CrMoAl alloy steel parts to be strengthened, and clean with acetone to thoroughly remove surface oil, dust and other impurities.

[0010] Step two involves remelting the material using an FC4000 diode laser manufactured by Beijing Thermal Stimulation Laser Technology Co., Ltd., and then laser-shocking the material using a Giant-3000 pulsed laser manufactured by Anshan Ziyu Laser Technology Co., Ltd. Based on the size and shape of the reinforced surface, the movement path of the IKO LWES15 CNC moving platform is set via a motion control module (a commercially available product), and the two-dimensional scanning trajectories of the remelting laser and the shock laser are planned (both the remelting laser and the shock laser are located on the CNC moving platform). The position of the shock laser is fixed, and the remelting laser is adjusted via a robotic arm to precisely control the center distance between the two laser spots.

[0011] Step 3: Place the workpiece in a protective atmosphere chamber and introduce argon gas with a purity greater than 99.5% through the inlet. Utilizing the property that argon gas is denser than air, the air inside the chamber is expelled through a small gap reserved on the upper side, forming a protective atmosphere.

[0012] Step four: Activate the remelting laser and scan the workpiece surface along a preset trajectory, causing its surface layer to melt instantly, forming a microscopic molten pool (the laser beam rapidly heats the irradiated area to above its melting point in a very short time, forming a thin microscopic molten pool). Subsequently, under the action of the workpiece's own cold substrate, the cooling rate can reach 10. 3 -10 5 ℃ / s, enabling the molten pool to solidify rapidly within 100-500 ms.

[0013] Step 5: With the relative positions of the remelting laser and the shock laser fixed (keeping the relative positions of the remelting laser and the center distance of the laser spot constant), the workpiece, which is still in the high-temperature solid phase region (580-1090 ℃) after remelting, is precisely and instantly moved to the spot of the shock laser using a moving platform, and laser shock strengthening is performed immediately.

[0014] Step six: After the strengthening process is completed, the workpiece is air-cooled to room temperature in a protective chamber with argon gas continuously supplied to ensure that it is not oxidized during the cooling process. The workpiece is completely isolated from oxygen during the cooling process to prevent the high-temperature surface from being oxidized, thereby maintaining the pure surface state and excellent performance of the strengthening layer.

[0015] Furthermore, in step two, since the positions of the two lasers are fixed, the impact laser lags behind the remelting laser and is synchronized with it. On the same path, it lags behind the remelting laser by a fixed center-to-center distance of the spot, triggering the pulsed laser to impact and strengthen the high-temperature area. Both the remelting laser and the impact laser are 4 mm circular spots, and the center-to-center distance between the remelting laser and the impact laser spots is 4.5-7.5 mm.

[0016] In step two, the positions of the remelting laser and the impact laser are fixed during the strengthening process. The 38CrMoAl alloy steel is moved only by the moving platform to ensure that the pulsed laser can perform in-situ synchronous impact on the remelted part.

[0017] The beneficial effects of adopting the above-mentioned further technical solutions are: ensuring that high-density dislocations and other crystal defects can be generated after pulsed laser to serve as non-uniform nucleation points, thereby significantly promoting heterogeneous nucleation of martensite during the subsequent cooling process.

[0018] Furthermore, in step two, the scanning trajectory is a unidirectional parallel scanning path: taking one boundary of the reinforced surface as a reference, a set of equally spaced parallel straight lines are set as the laser scanning path. The path spacing is calculated and determined based on the spot diameter and a preset overlap rate to ensure that the entire reinforced area is completely and uniformly covered.

[0019] Furthermore, in step three, high-purity argon gas is continuously introduced to ensure that the oxygen content remains below 200 ppm throughout the enhancement process.

[0020] In step three, the experiment is carried out when the oxygen concentration in the atmosphere protection chamber drops below 200 ppm, and argon gas is continuously introduced during the strengthening process to prevent oxidation of the strengthened surface.

[0021] The beneficial effect of adopting the above-mentioned further technical solution is to prevent oxidation on the material surface during the strengthening and cooling process.

[0022] Furthermore, in step four, the remelting laser power is 2000-4400 W, and the scanning speed is 450-1050 mm / min.

[0023] Furthermore, in step five, the energy of the pulsed laser is 2-3.5 J; the impact frequency is 7-10 Hz.

[0024] Furthermore, in step five, the impact laser spot and the remelting laser spot travel along the same path, and the angle between the impact laser and the workpiece surface is 45-90°.

[0025] Furthermore, the steel plate is made of 38CrMoAl alloy steel, and its chemical composition, by mass percentage, includes: 0.35%≤C≤0.42%; 0.2%≤Si≤0.45%; 0.3%≤Mn≤0.6%; 1.35%≤Cr≤1.65%; 0.7%≤Al≤1.1%; 0.15%≤Mo≤0.25%; the remainder being iron and impurities unavoidable during the production process.

[0026] The present invention discloses a laser remelting-laser shock in-situ synchronous surface strengthening method for 38CrMoAl alloy steel, which produces a strengthened 38CrMoAl alloy steel with an average hardness of 556-690 HV and a wear volume of 0.1375-0.3097 mm. 3 The fatigue strength is 2017.9-2219.4 MPa.

[0027] The reinforced 38CrMoAl alloy steel of this invention is widely used in the manufacture of key load-bearing components such as high-precision machine tool spindles and ball screws, aircraft landing gear actuators, and high-pressure chemical valve stems.

[0028] A key load-bearing component is prepared from the reinforced 38CrMoAl alloy steel of the present invention.

[0029] Compared with the prior art, the beneficial effects of the present invention are as follows: The laser remelting-laser shock in-situ synchronous surface strengthening method proposed in this invention, compared with single laser remelting, can refine the grains on the workpiece surface by introducing pulsed laser. Furthermore, conventional lasers, due to their high cooling rate, tend to leave large residual tensile stresses in the strengthened layer, thus reducing the workpiece's service life. However, pulsed lasers can introduce high-amplitude, deep-level residual compressive stresses on the remelted surface of the workpiece, inhibiting crack initiation and increasing nucleation sites or promoting the precipitation of strengthening phases, thereby improving the workpiece's wear resistance.

[0030] Compared to traditional offline impact methods, this invention enables the remelting laser and the impact laser to move synchronously in situ, achieving integrated, in-situ strengthening. Furthermore, it can directly impact the high-temperature solid phase region, intervening at the optimal metallurgical moment to maximize the utilization of impact energy, promoting dislocation slip and heterogeneous nucleation, transforming simple mechanical plastic deformation into a thermo-mechanical coupled metallurgical effect. Offline impact involves cold working on a completely cooled material surface, risking the introduction or amplification of damage. In contrast, the impact of this invention acts on an unstable high-temperature solid phase, and its shock wave energy can instantly suppress the initiation of remelting microcracks and promote the closure of defects such as porosity, achieving online repair of the remelting process. Moreover, the shock wave can be transmitted to the molten pool through vibration, promoting molten pool flow and further suppressing defects during solidification. Compared to offline impact, online impact simplifies the strengthening process, improves production efficiency, and reduces production costs. Furthermore, by controlling the distance between the impact spot and the remelting spot, the temperature of the impacted area can be determined, thereby avoiding secondary thermal effects of the heat generated by the impact on the strengthened surface.

[0031] This invention introduces laser shock peening during the laser remelting process, which not only alters the stress state of the reinforced layer but also enhances its hardness. Within the constrained range, a reinforced layer with a hardness in the range of 556-687 HV can be obtained. Compared to single remelting strengthening, the average hardness of the reinforced layer increases from 491 HV to 687 HV, an increase of 39.9%, and the wear volume decreases from 0.5258 mm. 3 Reduced to 0.1914 mm 3 The wear type after impact was reduced by 63.6%, and the wear type changed from adhesive wear + abrasive wear to fatigue wear. The contact fatigue strength increased from 1497.6 MPa to 2219.4 MPa, an increase of 48.3%.

[0032] This invention discloses a method for in-situ synchronous surface strengthening of 38CrMoAl alloy steel using laser remelting and laser shock blasting. The method includes the following steps: grinding, polishing, and rinsing the surface to be strengthened; determining the travel path and adjusting the distance between the remelting laser and the shock laser according to the desired surface strengthening; firstly, remelting the material surface under inert gas protection; and then using a pulsed laser to perform in-situ shock blasting on the remelted surface. Through the combined action of continuous and pulsed lasers, a high-quality surface strengthening layer of 38CrMoAl alloy steel is manufactured efficiently, energy-saving, and in an integrated manner, significantly improving the wear resistance of the strengthening layer and refining the wear pattern. Attached Figure Description

[0033] The technical solution and experimental results of the present invention will be further described in detail below with reference to the accompanying drawings and microscopic tissue photographs.

[0034] Figure 1 This is a schematic diagram of a laser remelting-laser shock in-situ synchronous surface strengthening method for 38CrMoAl alloy steel according to the present invention; wherein: 1-robotic arm; 2-laser remelting equipment; 3-pulsed laser equipment; 4-shock laser; 5-protective gas inlet; 6-remelting laser; 7-atmosphere protection chamber; 8-molten pool; 9-38CrMoAl alloy steel; 10-moving platform; Figure 2 IPF images of samples treated with different processes. (a) Laser remelting; (b) Laser remelting-laser shock. Figure 3 This is a comparison chart of the wear volume of samples treated with different processes. Detailed Implementation

[0035] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments. The following embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Example 1

[0036] This embodiment employs a laser remelting-laser shock in-situ synchronous surface strengthening method for 38CrMoAl alloy steel, as follows: Figure 1 The device shown includes a robotic arm 1; a laser remelting device 2; a pulsed laser device 3; an impact laser 4; a protective gas inlet 5; a remelting laser 6; an atmosphere protection chamber 7; a molten pool 8; 38CrMoAl alloy steel 9; and a moving platform 10.

[0037] The aforementioned device sets the travel path of the mobile platform 10 via a mobile control module (an existing commercially available product) and plans the two-dimensional scanning trajectories of the remelting laser 6 and the impact laser 4 (both the remelting laser device 2 and the pulsed laser device 3 are located on the mobile platform 10; the remelting laser 6 is generated by the laser remelting device 2, and the impact laser 4 is generated by the pulsed laser device 3). The position of the impact laser 4 is fixed, and the laser remelting device 2 is adjusted via the robotic arm 1. The 38CrMoAl alloy steel 9 is located inside the atmosphere protection chamber 7, which is equipped with a protective gas inlet 5. The remelting laser 6 and the impact laser 4 sequentially perform surface strengthening treatment on the 38CrMoAl alloy steel 9. The remelting laser 6 scans the surface of the 38CrMoAl alloy steel 9 workpiece along the preset trajectory, causing its surface layer to melt instantaneously, forming a molten pool 8.

[0038] 38CrMoAl alloy steel 9 has the following chemical composition by mass percentage: C 0.40%; Si 0.3%; Mn 0.4%; Cr 1.50%; Al 0.9%; Mo 0.20%; the remainder being iron and unavoidable impurities during the production process.

[0039] This embodiment provides a laser remelting-laser shock in-situ synchronous surface strengthening method for 38CrMoAl alloy steel, including the following steps: Step 1: Grind and polish the 38CrMoAl alloy steel to be strengthened (i.e., 38CrMoAl alloy steel 9), and use acetone to clean it to thoroughly remove surface oil, dust and other impurities. Step two: Based on the size and shape of the reinforced surface, the movement path of the moving platform 10 is set through the movement control module, and the two-dimensional scanning trajectories of the remelting laser 6 (generated by the laser remelting device 2) and the impact laser 4 (generated by the pulsed laser device 3) are planned. The position of the impact laser 4 is fixed, and the remelting laser device 2 is adjusted by the robotic arm 1 to precisely control the center distance between the two laser spots of the remelting laser 6 and the impact laser 4 to be 6 mm. Step 3: Place the workpiece to be strengthened (i.e., 38CrMoAl alloy steel 9) in the atmosphere protection chamber 7, and introduce high-purity argon gas through the protective gas inlet 5. Taking advantage of the fact that argon gas is denser than air, the air in the chamber is discharged through the small gap reserved on the upper side until the oxygen concentration in the atmosphere protection chamber 7 drops below 200 ppm; Step four: Turn on the remelting laser 6 and scan the workpiece surface along a preset trajectory, causing its surface layer to melt instantly and form a microscopic molten pool 8. The remelting laser 6 has a power of 3000 W and a scanning speed of 600 mm / min. Subsequently, ultra-fast solidification is completed under the rapid heat conduction of the substrate. Step 5: With the remelting laser 6 and the shock laser 4 fixed in relative positions, the solid phase region that is still at high temperature after remelting is precisely moved to the shock laser spot by the moving platform 10, and laser shock strengthening is performed immediately. The shock laser 4 has an energy of 3 J, a frequency of 10 Hz, and is at a 60° angle to the surface of the workpiece to be strengthened. Step six: After the strengthening process is completed, the workpiece is cooled to room temperature in a protective atmosphere chamber 7 with argon gas continuously supplied to ensure that it is not oxidized during the cooling process.

[0040] By bombarding the material surface with plasma generated by a pulsed laser, the shock wave is transmitted into the material's interior, thereby improving the microstructure and properties of the reinforced layer. The reinforced layer treated with this process has an average hardness of approximately 687 HV and a wear volume of 0.1914 mm. 3 The contact fatigue strength is 2219.4 MPa.

[0041] The reinforced 38CrMoAl alloy steel obtained in this embodiment is widely used in the manufacture of key load-bearing components such as high-precision machine tool spindles and ball screws, aircraft landing gear actuators, and high-pressure chemical valve stems.

[0042] like Figure 2 As shown in the figures, Figure a is the IPF image of the reinforced layer after laser remelting in Comparative Example 1, and Figure b is the IPF image of the reinforced layer after laser remelting-laser shock in-situ synchronous surface strengthening treatment in this embodiment. As can be seen, compared to the single laser remelting treatment in Comparative Example 1 (Figure a), the laser remelting-laser shock in-situ synchronous surface strengthening treatment used in this embodiment (Figure b) significantly refines the grain size of the reinforced layer and makes its crystal orientation distribution more uniform and random, effectively improving the anisotropy of the microstructure. The synergistic effect of thermo-mechanical coupling not only suppresses the generation of micro-defects but also improves the stress state of the reinforced surface, thereby fundamentally improving the comprehensive mechanical properties of the material surface, such as hardness, strength, and fatigue resistance.

[0043] like Figure 3 The image shows a comparison of the wear volume of samples under different processing methods. The wear volume of the untreated sample (i.e., 38CrMoAl alloy steel 9, without any treatment) is 0.9451 mm. 3 The wear volume of the reinforced alloy steel after laser remelting in Comparative Example 1 was 0.5258 mm. 3 In this embodiment, the wear volume of the reinforced alloy steel after laser remelting-laser shock in-situ synchronous surface strengthening treatment is 0.1914 mm.3 In this embodiment, after laser impact, the wear volume decreased from 0.5258 mm. 3 Reduced to 0.1914 mm 3 This represents a decrease of 63.6%. Example 2

[0044] A method for in-situ synchronous surface strengthening of 38CrMoAl alloy steel by laser remelting-laser shock osmosis includes the following steps: Step 1: Grind and polish the 38CrMoAl alloy steel parts to be strengthened, and clean with acetone to thoroughly remove surface oil, dust and other impurities. The chemical composition of 38CrMoAl alloy steel, by mass percentage, includes: C 0.35%; Si 0.2%; Mn 0.3%; Cr 1.35%; Al 0.7%; Mo 0.15%; the remainder being iron and unavoidable impurities from the production process. Step two: Based on the size and shape of the reinforced surface, the movement path of the moving platform 10 is set through the movement control module, and the two-dimensional scanning trajectories of the remelting laser and the impact laser are planned. The position of the impact laser is fixed, and the remelting laser equipment is adjusted by the robotic arm 1 to precisely control the center distance between the two laser spots of the remelting laser 6 and the impact laser 4 to be 6 mm. Step 3: Place the workpiece to be strengthened in the atmosphere protection chamber 7, and introduce high-purity argon gas through the protective gas inlet 5. Taking advantage of the fact that argon gas is denser than air, the air in the chamber is discharged through the small gap reserved on the upper side until the oxygen concentration in the atmosphere protection chamber drops below 200 ppm; Step four: Turn on the remelting laser 6 and scan the workpiece surface along a preset trajectory, causing its surface layer to melt instantly and form a microscopic molten pool 8. The remelting laser 6 has a power of 2000 W and a scanning speed of 600 mm / min. Subsequently, ultra-fast solidification is completed under the rapid heat conduction of the substrate. Step 5: With the relative positions of the remelting laser and the shock laser fixed, the solid phase region that is still at high temperature after remelting is precisely moved to the spot of the shock laser by the moving platform 10, and laser shock strengthening is performed immediately. The shock laser 4 has an energy of 3 J, a frequency of 10 Hz, and is at a 60° angle to the surface of the workpiece to be strengthened. Step six: After the strengthening process is completed, the workpiece is cooled to room temperature in a protective chamber with argon gas continuously supplied to ensure that it is not oxidized during the cooling process.

[0045] The reinforced layer after this process has an average hardness of approximately 556 HV and a wear volume of 0.2901 mm. 3 The wear types are adhesive wear and a small amount of abrasive wear.

[0046] The reinforced 38CrMoAl alloy steel obtained in this embodiment is widely used in the manufacture of key load-bearing components such as high-precision machine tool spindles and ball screws, aircraft landing gear actuators, and high-pressure chemical valve stems. Example 3

[0047] A method for in-situ synchronous surface strengthening of 38CrMoAl alloy steel by laser remelting-laser shock osmosis includes the following steps: Step 1: Grind and polish the 38CrMoAl alloy steel parts to be strengthened, and clean with acetone to thoroughly remove surface oil, dust and other impurities. The chemical composition of 38CrMoAl alloy steel, by mass percentage, includes: C 0.42%; Si 0.45%; Mn 0.6%; Cr 1.65%; Al 1.1%; Mo 0.25%; the remainder being iron and unavoidable impurities from the production process.

[0048] Step two: Based on the size and shape of the reinforced surface, the movement path of the moving platform 10 is set through the movement control module, and the two-dimensional scanning trajectories of the remelting laser and the impact laser are planned. The position of the impact laser is fixed, and the remelting laser equipment is adjusted by the robotic arm 1 to precisely control the center distance between the two laser spots of the remelting laser 6 and the impact laser 4 to be 6 mm. Step 3: Place the workpiece to be strengthened in the atmosphere protection chamber 7, and introduce high-purity argon gas through the protective gas inlet 5. Taking advantage of the fact that argon gas is denser than air, the air in the chamber is discharged through the small gap reserved on the upper side until the oxygen concentration in the atmosphere protection chamber drops below 200 ppm; Step four: Turn on the remelting laser 6 and scan the workpiece surface along a preset trajectory, causing its surface layer to melt instantly and form a microscopic molten pool 8. The remelting laser 6 has a power of 4400 W and a scanning speed of 600 mm / min. Subsequently, ultra-fast solidification is completed under the rapid heat conduction of the substrate. Step 5: With the relative positions of the remelting laser and the shock laser fixed, the solid phase region that is still at high temperature after remelting is precisely moved to the spot of the shock laser by the moving platform 10, and laser shock strengthening is performed immediately. The shock laser 4 has an energy of 3 J, a frequency of 10 Hz, and is at a 60° angle to the surface of the workpiece to be strengthened. The reinforced layer after this process has an average hardness of approximately 659 HV and a wear volume of 0.2048 mm. 3 The wear types are fatigue wear and a small amount of abrasive wear.

[0049] The reinforced 38CrMoAl alloy steel obtained in this embodiment is widely used in the manufacture of key load-bearing components such as high-precision machine tool spindles and ball screws, aircraft landing gear actuators, and high-pressure chemical valve stems. Example 4

[0050] A method for in-situ synchronous surface strengthening of 38CrMoAl alloy steel by laser remelting-laser shock osmosis includes the following steps: Step 1: Grind and polish the parts of the 38CrMoAl alloy steel (composition same as in Example 1) to be strengthened, and clean with acetone to thoroughly remove surface oil, dust and other impurities. Step two: Based on the size and shape of the reinforced surface, the movement path of the moving platform 10 is set through the movement control module, and the two-dimensional scanning trajectories of the remelting laser and the impact laser are planned. The position of the impact laser is fixed, and the remelting laser equipment is adjusted by the robotic arm to precisely control the center distance between the two laser spots of the remelting laser 6 and the impact laser 4 to be 6 mm. Step 3: Place the workpiece to be strengthened in the atmosphere protection chamber 7, and introduce high-purity argon gas through the protective gas inlet 5. Taking advantage of the fact that argon gas is denser than air, the air in the chamber is discharged through the small gap reserved on the upper side until the oxygen concentration in the atmosphere protection chamber drops below 200 ppm; Step four: Turn on the remelting laser 6 and scan the workpiece surface along a preset trajectory, causing its surface layer to melt instantly and form a microscopic molten pool 8. The remelting laser 6 has a power of 3000 W and a scanning speed of 1050 mm / min. Subsequently, ultra-fast solidification is completed under the rapid heat conduction of the substrate. With the relative positions of the remelting laser and the shock laser fixed, the solid phase region that is still at high temperature after remelting is precisely moved to the spot of the shock laser by the moving platform 10, and laser shock strengthening is performed immediately. The shock laser 4 has an energy of 3 J, a frequency of 10 Hz, and is at a 60° angle to the surface of the workpiece to be strengthened. After the strengthening process is completed, the workpiece is cooled to room temperature in a protective chamber with argon gas continuously supplied to ensure that it is not oxidized during the cooling process.

[0051] The reinforced layer after this process has an average hardness of approximately 567 HV and a wear volume of 0.3097 mm. 3 Under the high compressive stress introduced by impact, the wear type is fatigue wear.

[0052] The reinforced 38CrMoAl alloy steel obtained in this embodiment is widely used in the manufacture of key load-bearing components such as high-precision machine tool spindles and ball screws, aircraft landing gear actuators, and high-pressure chemical valve stems. Example 5

[0053] A method for in-situ synchronous surface strengthening of 38CrMoAl alloy steel by laser remelting-laser shock osmosis includes the following steps: Step 1: Grind and polish the parts of the 38CrMoAl alloy steel (composition same as in Example 1) to be strengthened, and clean with acetone to thoroughly remove surface oil, dust and other impurities. Step two: Based on the size and shape of the reinforced surface, the movement path of the moving platform 10 is set through the movement control module, and the two-dimensional scanning trajectories of the remelting laser and the impact laser are planned. The position of the impact laser is fixed, and the remelting laser equipment is adjusted by the robotic arm to precisely control the center distance between the two laser spots of the remelting laser 6 and the impact laser 4 to be 6 mm. Step 3: Place the workpiece to be strengthened in the atmosphere protection chamber 7, and introduce high-purity argon gas through the protective gas inlet 5. Taking advantage of the fact that argon gas is denser than air, the air in the chamber is discharged through the small gap reserved on the upper side until the oxygen concentration in the atmosphere protection chamber drops below 200 ppm; Step four: Turn on the remelting laser 6 and scan the workpiece surface along a preset trajectory, causing its surface layer to melt instantly and form a microscopic molten pool 8. The remelting laser 6 has a power of 3000 W and a scanning speed of 450 mm / min. Subsequently, ultra-fast solidification is completed under the rapid heat conduction of the substrate. Step 5: With the relative positions of the remelting laser and the shock laser fixed, the solid phase region that is still at high temperature after remelting is precisely moved to the spot of the shock laser by the moving platform 10, and laser shock strengthening is performed immediately. The shock laser 4 has an energy of 3 J, a frequency of 10 Hz, and is at a 60° angle to the surface of the workpiece to be strengthened. Step six: After the strengthening process is completed, the workpiece is cooled to room temperature in a protective chamber with argon gas continuously supplied to ensure that it is not oxidized during the cooling process.

[0054] The reinforced layer after this process has an average hardness of approximately 690 HV and a wear volume of 0.1375 mm. 3 Under the high compressive stress introduced by impact, the wear type is fatigue wear.

[0055] The reinforced 38CrMoAl alloy steel obtained in this embodiment is widely used in the manufacture of key load-bearing components such as high-precision machine tool spindles and ball screws, aircraft landing gear actuators, and high-pressure chemical valve stems. Example 6

[0056] A method for in-situ synchronous surface strengthening of 38CrMoAl alloy steel by laser remelting-laser shock osmosis includes the following steps: Step 1: Grind and polish the parts of the 38CrMoAl alloy steel (composition same as in Example 1) to be strengthened, and clean with acetone to thoroughly remove surface oil, dust and other impurities. Step two: Based on the size and shape of the reinforced surface, the movement path of the moving platform 10 is set through the movement control module, and the two-dimensional scanning trajectories of the remelting laser and the impact laser are planned. The position of the impact laser is fixed, and the remelting laser equipment is adjusted by the robotic arm to precisely control the center distance between the two laser spots of the remelting laser 6 and the impact laser 4 to be 4.5 mm. Step 3: Connect the workpiece to be strengthened to a thermocouple thermometer for real-time temperature measurement and place it in the atmosphere protection chamber 7. Introduce high-purity argon gas through the protective gas inlet 5. Utilizing the property that argon gas is denser than air, exhaust the air in the chamber through the small gap reserved on the upper side until the oxygen concentration in the atmosphere protection chamber drops below 200 ppm. Step four: Turn on the remelting laser 6 and scan the workpiece surface along a preset trajectory, causing its surface layer to melt instantly and form a microscopic molten pool 8. The remelting laser 6 has a power of 3000 W and a scanning speed of 600 mm / min. Subsequently, ultra-fast solidification is completed under the rapid heat conduction of the substrate. Step 5: With the relative positions of the remelting laser and the shock laser fixed, the solid phase region that is still at high temperature after remelting is precisely moved to the spot of the shock laser by the moving platform 10, and laser shock strengthening is performed immediately. The shock laser 4 has an energy of 3 J, a frequency of 10 Hz, and is at a 60° angle to the surface of the workpiece to be strengthened. Step six: After the strengthening process is completed, the workpiece is cooled to room temperature in a protective chamber with argon gas continuously supplied to ensure that it is not oxidized during the cooling process.

[0057] The reinforced layer after this process has an average hardness of approximately 607 HV, a temperature range of approximately 730 ℃-1090 ℃ at the impact site, a contact fatigue strength of 2089.0 MPa, and a wear volume of 0.2778 mm. 3 The wear type is fatigue wear.

[0058] The reinforced 38CrMoAl alloy steel obtained in this embodiment is widely used in the manufacture of key load-bearing components such as high-precision machine tool spindles and ball screws, aircraft landing gear actuators, and high-pressure chemical valve stems. Example 7

[0059] A method for in-situ synchronous surface strengthening of 38CrMoAl alloy steel by laser remelting-laser shock osmosis includes the following steps: Step 1: Grind and polish the parts of the 38CrMoAl alloy steel (composition same as in Example 1) to be strengthened, and clean with acetone to thoroughly remove surface oil, dust and other impurities. Step two: Based on the size and shape of the reinforced surface, the movement path of the moving platform 10 is set through the movement control module, and the two-dimensional scanning trajectories of the remelting laser and the impact laser are planned. The position of the impact laser is fixed, and the remelting laser equipment is adjusted by the robotic arm to precisely control the center distance between the two laser spots of the remelting laser 6 and the impact laser 4 to be 7.5 mm. Step 3: Connect the workpiece to be strengthened to a thermocouple thermometer for real-time temperature measurement and place it in the atmosphere protection chamber 7. Introduce high-purity argon gas through the protective gas inlet 5. Utilizing the property that argon gas is denser than air, exhaust the air in the chamber through the small gap reserved on the upper side until the oxygen concentration in the atmosphere protection chamber drops below 200 ppm. Step four: Turn on the remelting laser 6 and scan the workpiece surface along a preset trajectory, causing its surface layer to melt instantly and form a microscopic molten pool 8. The remelting laser 6 has a power of 3000 W and a scanning speed of 600 mm / min. Subsequently, ultra-fast solidification is completed under the rapid heat conduction of the substrate. Step 5: With the relative positions of the remelting laser and the shock laser fixed, the solid phase region that is still at high temperature after remelting is precisely moved to the spot of the shock laser by the moving platform 10, and laser shock strengthening is performed immediately. The shock laser 4 has an energy of 3 J, a frequency of 10 Hz, and is at a 60° angle to the surface of the workpiece to be strengthened. Step six: After the strengthening process is completed, the workpiece is cooled to room temperature in a protective chamber with argon gas continuously supplied to ensure that it is not oxidized during the cooling process.

[0060] The reinforced layer after this process has an average hardness of approximately 572 HV, a temperature range of approximately 580 ℃-840 ℃ at the impact site, a contact fatigue strength of 2017.9 MPa, and a wear volume of 0.2909 mm. 3 The wear types are fatigue wear and a small amount of abrasive wear.

[0061] The reinforced 38CrMoAl alloy steel obtained in this embodiment is widely used in the manufacture of key load-bearing components such as high-precision machine tool spindles and ball screws, aircraft landing gear actuators, and high-pressure chemical valve stems. Example 8

[0062] A method for in-situ synchronous surface strengthening of 38CrMoAl alloy steel by laser remelting-laser shock osmosis includes the following steps: Step 1: Grind and polish the parts of the 38CrMoAl alloy steel (composition same as in Example 1) to be strengthened, and clean with acetone to thoroughly remove surface oil, dust and other impurities. Step two: Based on the size and shape of the reinforced surface, the movement path of the moving platform 10 is set through the movement control module, and the two-dimensional scanning trajectories of the remelting laser and the impact laser are planned. The position of the impact laser is fixed, and the remelting laser equipment is adjusted by the robotic arm to precisely control the center distance between the two laser spots of the remelting laser 6 and the impact laser 4 to be 6 mm. Step 3: Place the workpiece to be strengthened in the atmosphere protection chamber 7, and introduce high-purity argon gas through the protective gas inlet 5. Taking advantage of the fact that argon gas is denser than air, the air in the chamber is discharged through the small gap reserved on the upper side until the oxygen concentration in the atmosphere protection chamber drops below 200 ppm; Step four: Turn on the remelting laser 6 and scan the workpiece surface along a preset trajectory, causing its surface layer to melt instantly and form a microscopic molten pool 8. The remelting laser 6 has a power of 3000 W and a scanning speed of 600 mm / min. Subsequently, ultra-fast solidification is completed under the rapid heat conduction of the substrate. Step 5: With the relative positions of the remelting laser and the shock laser fixed, the solid phase region that is still at high temperature after remelting is precisely moved to the spot of the shock laser by the moving platform 10, and laser shock strengthening is performed immediately. The shock laser 6 has an energy of 2 J, a frequency of 10 Hz, and is at a 60° angle to the surface of the workpiece to be strengthened. Step six: After the strengthening process is completed, the workpiece is cooled to room temperature in a protective chamber with argon gas continuously supplied to ensure that it is not oxidized during the cooling process.

[0063] The reinforced layer after this process has an average hardness of approximately 598 HV and a wear volume of 0.2973 mm. 3 The wear type is abrasive wear.

[0064] The reinforced 38CrMoAl alloy steel obtained in this embodiment is widely used in the manufacture of key load-bearing components such as high-precision machine tool spindles and ball screws, aircraft landing gear actuators, and high-pressure chemical valve stems. Example 9

[0065] A method for in-situ synchronous surface strengthening of 38CrMoAl alloy steel by laser remelting-laser shock osmosis includes the following steps: Step 1: Grind and polish the parts of the 38CrMoAl alloy steel (composition same as in Example 1) to be strengthened, and clean with acetone to thoroughly remove surface oil, dust and other impurities. Step two: Based on the size and shape of the reinforced surface, the movement path of the moving platform 10 is set through the movement control module, and the two-dimensional scanning trajectories of the remelting laser and the impact laser are planned. The position of the impact laser is fixed, and the remelting laser equipment is adjusted by the robotic arm to precisely control the center distance between the two laser spots of the remelting laser 6 and the impact laser 4 to be 6 mm. Step 3: Place the workpiece to be strengthened in the atmosphere protection chamber 7, and introduce high-purity argon gas through the protective gas inlet 5. Taking advantage of the fact that argon gas is denser than air, the air in the chamber is discharged through the small gap reserved on the upper side until the oxygen concentration in the atmosphere protection chamber drops below 200 ppm; Step four: Turn on the remelting laser 6 and scan the workpiece surface along a preset trajectory, causing its surface layer to melt instantly and form a microscopic molten pool 8. The remelting laser 6 has a power of 3000 W and a scanning speed of 600 mm / min. Subsequently, ultra-fast solidification is completed under the rapid heat conduction of the substrate. Step 5: With the remelting laser and the shock laser in fixed relative positions, the solid phase region that is still at high temperature after remelting is precisely moved to the shock laser spot by the moving platform 10, and laser shock strengthening is performed immediately. The shock laser 4 has an energy of 3.5 J, a frequency of 10 Hz, and is at a 60° angle to the surface of the workpiece to be strengthened. Step six: After the strengthening process is completed, the workpiece is cooled to room temperature in a protective chamber with argon gas continuously supplied to ensure that it is not oxidized during the cooling process.

[0066] The reinforced layer after this process has an average hardness of approximately 639 HV and a wear volume of 0.2323 mm. 3 The wear type is fatigue wear.

[0067] The reinforced 38CrMoAl alloy steel obtained in this embodiment is widely used in the manufacture of key load-bearing components such as high-precision machine tool spindles and ball screws, aircraft landing gear actuators, and high-pressure chemical valve stems. Example 10

[0068] A method for in-situ synchronous surface strengthening of 38CrMoAl alloy steel by laser remelting-laser shock osmosis includes the following steps: Step 1: Grind and polish the parts of the 38CrMoAl alloy steel (composition same as in Example 1) to be strengthened, and clean with acetone to thoroughly remove surface oil, dust and other impurities. Step two: Based on the size and shape of the reinforced surface, the movement path of the moving platform 10 is set through the movement control module, and the two-dimensional scanning trajectories of the remelting laser and the impact laser are planned. The position of the impact laser is fixed, and the remelting laser equipment is adjusted by the robotic arm to precisely control the center distance between the two laser spots of the remelting laser 6 and the impact laser 4 to be 6 mm. Step 3: Place the workpiece to be strengthened in the atmosphere protection chamber 7, and introduce high-purity argon gas through the protective gas inlet 5. Taking advantage of the fact that argon gas is denser than air, the air in the chamber is discharged through the small gap reserved on the upper side until the oxygen concentration in the atmosphere protection chamber drops below 200 ppm; Step four: Turn on the remelting laser 6 and scan the workpiece surface along a preset trajectory, causing its surface layer to melt instantly and form a microscopic molten pool 8. The remelting laser 6 has a power of 3000 W and a scanning speed of 600 mm / min. Subsequently, ultra-fast solidification is completed under the rapid heat conduction of the substrate. Step 5: With the relative positions of the remelting laser and the shock laser fixed, the solid phase region that is still at high temperature after remelting is precisely moved to the spot of the shock laser by the moving platform 10, and laser shock strengthening is performed immediately. The shock laser 4 has an energy of 3 J, a frequency of 10 Hz, and is at a 45° angle to the surface of the workpiece to be strengthened. Step six: After the strengthening process is completed, the workpiece is cooled to room temperature in a protective chamber with argon gas continuously supplied to ensure that it is not oxidized during the cooling process.

[0069] The reinforced layer after this process has an average hardness of approximately 637 HV and a wear volume of 0.2321 mm. 3 The wear type is fatigue wear.

[0070] The reinforced 38CrMoAl alloy steel obtained in this embodiment is widely used in the manufacture of key load-bearing components such as high-precision machine tool spindles and ball screws, aircraft landing gear actuators, and high-pressure chemical valve stems. Example 11

[0071] A method for in-situ synchronous surface strengthening of 38CrMoAl alloy steel by laser remelting-laser shock osmosis includes the following steps: Step 1: Grind and polish the parts of the 38CrMoAl alloy steel (composition same as in Example 1) to be strengthened, and clean with acetone to thoroughly remove surface oil, dust and other impurities. Step two: Based on the size and shape of the reinforced surface, the movement path of the moving platform 10 is set through the movement control module, and the two-dimensional scanning trajectories of the remelting laser and the impact laser are planned. The position of the impact laser is fixed, and the remelting laser equipment is adjusted by the robotic arm to precisely control the center distance between the two laser spots of the remelting laser 6 and the impact laser 4 to be 6 mm. Step 3: Place the workpiece to be strengthened in the atmosphere protection chamber 7, and introduce high-purity argon gas through the protective gas inlet 5. Taking advantage of the fact that argon gas is denser than air, the air in the chamber is discharged through the small gap reserved on the upper side until the oxygen concentration in the atmosphere protection chamber drops below 200 ppm; Step four: Turn on the remelting laser 6 and scan the workpiece surface along a preset trajectory, causing its surface layer to melt instantly and form a microscopic molten pool 8. The remelting laser 6 has a power of 3000 W and a scanning speed of 600 mm / min. Subsequently, ultra-fast solidification is completed under the rapid heat conduction of the substrate. Step 5: With the relative positions of the remelting laser and the shock laser fixed, the solid phase region that is still at high temperature after remelting is precisely moved to the spot of the shock laser by the moving platform 10, and laser shock strengthening is performed immediately. The shock laser 4 has an energy of 3 J, a frequency of 7 Hz, and is at a 90° angle to the surface of the workpiece to be strengthened. Step six: After the strengthening process is completed, the workpiece is cooled to room temperature in a protective chamber with argon gas continuously supplied to ensure that it is not oxidized during the cooling process.

[0072] The reinforced layer after this process has an average hardness of approximately 633 HV and a wear volume of 0.2671 mm. 3 The wear type is fatigue wear.

[0073] The reinforced 38CrMoAl alloy steel obtained in this embodiment is widely used in the manufacture of key load-bearing components such as high-precision machine tool spindles and ball screws, aircraft landing gear actuators, and high-pressure chemical valve stems. Comparative Example 1

[0074] The laser remelting surface strengthening method for 38CrMoAl alloy steel includes the following steps: Step 1: Grind and polish the parts of the 38CrMoAl alloy steel (composition same as in Example 1) to be strengthened, and clean with acetone to thoroughly remove surface oil, dust and other impurities. Step 2: Based on the size and shape of the reinforced surface, the movement path of the moving platform 10 is set through the movement control module, and the two-dimensional scanning trajectory of the remelting laser is planned. Step 3: Place the workpiece to be strengthened in the atmosphere protection chamber 7, and introduce high-purity argon gas through the protective gas inlet 5. Taking advantage of the fact that argon gas is denser than air, the air in the chamber is discharged through the small gap reserved on the upper side until the oxygen concentration in the atmosphere protection chamber drops below 200 ppm; Step four: Turn on the remelting laser 6 and scan the workpiece surface along a preset trajectory, causing its surface layer to melt instantly and form a microscopic molten pool 8. The remelting laser 6 has a power of 3000 W and a scanning speed of 600 mm / min. Subsequently, ultra-fast solidification is completed under the rapid heat conduction of the substrate. Step 5: After the strengthening process is completed, the workpiece is cooled to room temperature in a protective chamber with argon gas continuously supplied to ensure that it is not oxidized during the cooling process.

[0075] Compared to Example 1, Comparative Example 1 did not undergo laser shock treatment. The reinforced layer treated with this process had an average hardness of approximately 491 HV and a wear volume of 0.5258 mm. 3 The contact fatigue strength was 1497.6 MPa. Compared to the repaired component without laser shock, Example 1 showed an average hardness increase of approximately 200 HV and a wear volume reduction from 0.5258 mm².3 Reduced to 0.1914 mm 3 After impact, the wear type changed from adhesive wear + abrasive wear to fatigue wear. The contact fatigue strength of Example 1 after impact was 48.3% higher than that of Comparative Example 1 without impact. The shock wave pressure after internal strengthening of the material in Example 1 can induce deeper and more intense plastic deformation, change the stress state, and introduce unprecedentedly high density of dislocations, stacking faults, and even deformation twins at the grain boundaries, resulting in significant dislocation strengthening. Furthermore, high-density dislocations and other crystal defects act as non-uniform nucleation sites, which can significantly promote heterogeneous nucleation of new phases during subsequent cooling, resulting in better fine grain strengthening and precipitation strengthening effects. Comparative Example 2

[0076] The in-situ synchronous surface strengthening method of 38CrMoAl alloy steel by laser remelting and impact includes the following steps: Step 1: Grind and polish the parts of the 38CrMoAl alloy steel (composition same as in Example 2) to be strengthened, and clean with acetone to thoroughly remove surface oil, dust and other impurities. Step two: Based on the size and shape of the reinforced surface, the movement path of the moving platform 10 is set through the movement control module, and the two-dimensional scanning trajectories of the remelting laser and the impact laser are planned. The position of the impact laser is fixed, and the remelting laser equipment is adjusted by the robotic arm to precisely control the center distance between the two laser spots of the remelting laser 6 and the impact laser 4 to be 6 mm. Step 3: Place the workpiece to be strengthened in the atmosphere protection chamber 7, and introduce high-purity argon gas through the protective gas inlet 5. Taking advantage of the fact that argon gas is denser than air, the air in the chamber is discharged through the small gap reserved on the upper side until the oxygen concentration in the atmosphere protection chamber drops below 200 ppm; Step four: Turn on the remelting laser 6 and scan the workpiece surface along a preset trajectory, causing its surface layer to melt instantly and form a microscopic molten pool 8. The remelting laser 6 has a power of 1800 W and a scanning speed of 600 mm / min. Subsequently, ultra-fast solidification is completed under the rapid heat conduction of the substrate. Step 5: With the relative positions of the remelting laser and the shock laser fixed, the solid phase region that is still at high temperature after remelting is precisely moved to the spot of the shock laser by the moving platform 10, and laser shock strengthening is performed immediately. The shock laser 4 has an energy of 3 J, a frequency of 10 Hz, and is at a 60° angle to the surface of the workpiece to be strengthened. Step six: After the strengthening process is completed, the workpiece is cooled to room temperature in a protective chamber with argon gas continuously supplied to ensure that it is not oxidized during the cooling process.

[0077] Compared to Example 2, Comparative Example 2 reduced the power of the remelting laser from 2000 W to 1800 W. The average hardness of the reinforced layer after this process was approximately 509 HV, and the wear volume was 0.3478 mm. 3 The wear types are fatigue wear and abrasive wear. Due to insufficient heat input and excessively high material yield strength at the time of impact, the strengthening effect of laser shock descent decreases sharply, causing the strengthening effect to degenerate from deep thermal synergy to weak synergy dominated by shallow forces, thus failing to fully realize the strengthening effect brought about by the impact. Comparative Example 3

[0078] The in-situ synchronous surface strengthening method of 38CrMoAl alloy steel by laser remelting and impact includes the following steps: Step 1: Grind and polish the parts of the 38CrMoAl alloy steel (composition same as in Example 3) to be strengthened, and clean with acetone to thoroughly remove surface oil, dust and other impurities. Step two: Based on the size and shape of the reinforced surface, the movement path of the moving platform 10 is set through the movement control module, and the two-dimensional scanning trajectories of the remelting laser and the impact laser are planned. The position of the impact laser is fixed, and the remelting laser equipment is adjusted by the robotic arm to precisely control the center distance between the two laser spots of the remelting laser 6 and the impact laser 4 to be 6 mm. Step 3: Place the workpiece to be strengthened in the atmosphere protection chamber 7, and introduce high-purity argon gas through the protective gas inlet 5. Taking advantage of the fact that argon gas is denser than air, the air in the chamber is discharged through the small gap reserved on the upper side until the oxygen concentration in the atmosphere protection chamber drops below 200 ppm; Step four: Turn on the remelting laser 6 and scan the workpiece surface along a preset trajectory, causing its surface layer to melt instantly and form a microscopic molten pool 8. The remelting laser 6 has a power of 4600 W and a scanning speed of 600 mm / min. Subsequently, ultra-fast solidification is completed under the rapid heat conduction of the substrate. Step 5: With the relative positions of the remelting laser and the shock laser fixed, the solid phase region that is still at high temperature after remelting is precisely moved to the spot of the shock laser by the moving platform 10, and laser shock strengthening is performed immediately. The shock laser 4 has an energy of 3 J, a frequency of 10 Hz, and is at a 60° angle to the surface of the workpiece to be strengthened. Step six: After the strengthening process is completed, the workpiece is cooled to room temperature in a protective chamber with argon gas continuously supplied to ensure that it is not oxidized during the cooling process.

[0079] Compared to Example 3, Comparative Example 3 increased the power of the remelting laser from 4400 W to 4600 W. The average hardness of the reinforced layer after this process was approximately 538 HV, and the wear volume was 0.3545 mm. 3The wear types are fatigue wear and abrasive wear. Increased power increases the depth of the hardened layer and provides a more favorable state for impact plastic deformation, but at the same time it causes microstructure coarsening, surface overheating, thermal deformation of the workpiece, surface ablation and increased roughness, so the overall strengthening effect decreases instead of increasing. Comparative Example 4

[0080] The in-situ synchronous surface strengthening method of 38CrMoAl alloy steel by laser remelting and impact includes the following steps: Step 1: Grind and polish the parts of the 38CrMoAl alloy steel (composition same as in Example 1) to be strengthened, and clean with acetone to thoroughly remove surface oil, dust and other impurities. Step two: Based on the size and shape of the reinforced surface, the movement path of the moving platform 10 is set through the movement control module, and the two-dimensional scanning trajectories of the remelting laser and the impact laser are planned. The position of the impact laser is fixed, and the remelting laser equipment is adjusted by the robotic arm to precisely control the center distance between the two laser spots of the remelting laser 6 and the impact laser 4 to be 6 mm. Step 3: Place the workpiece to be strengthened in the atmosphere protection chamber 7, and introduce high-purity argon gas through the protective gas inlet 5. Taking advantage of the fact that argon gas is denser than air, the air in the chamber is discharged through the small gap reserved on the upper side until the oxygen concentration in the atmosphere protection chamber drops below 200 ppm; Step four: Turn on the remelting laser 6 and scan the workpiece surface along a preset trajectory, causing its surface layer to melt instantly and form a microscopic molten pool 8. The remelting laser 6 has a power of 3000 W and a scanning speed of 1200 mm / min. Subsequently, ultra-fast solidification is completed under the rapid heat conduction of the substrate. Step 5: With the relative positions of the remelting laser and the shock laser fixed, the solid phase region that is still at high temperature after remelting is precisely moved to the spot of the shock laser by the moving platform 10, and laser shock strengthening is performed immediately. The shock laser 4 has an energy of 3 J, a frequency of 10 Hz, and is at a 60° angle to the surface of the workpiece to be strengthened. Step six: After the strengthening process is completed, the workpiece is cooled to room temperature in a protective chamber with argon gas continuously supplied to ensure that it is not oxidized during the cooling process.

[0081] Compared to Example 4, the scanning speed of Comparative Example 4 increased from 1050 mm / min to 1200 mm / min. With a fixed impact frequency of the impact laser, the scanning speed directly affects the overlap rate of the impact spots. Compared to the scanning speed of Example 4, the overlap rate of the impact spots in Comparative Example 4 decreased from 56.25% to 50%. Because fewer impacts are received per unit area, the strengthening effect on the material surface is weakened. The average hardness of the reinforced layer after this process is approximately 511 HV, and the wear volume is 0.3857 mm². 3 The wear type is fatigue wear. Comparative Example 5

[0082] The in-situ synchronous surface strengthening method of 38CrMoAl alloy steel by laser remelting and impact includes the following steps: Step 1: Grind and polish the parts of the 38CrMoAl alloy steel (composition same as in Example 1) to be strengthened, and clean with acetone to thoroughly remove surface oil, dust and other impurities. Step two: Based on the size and shape of the reinforced surface, the movement path of the moving platform 10 is set through the movement control module, and the two-dimensional scanning trajectories of the remelting laser and the impact laser are planned. The position of the impact laser is fixed, and the remelting laser equipment is adjusted by the robotic arm to precisely control the center distance between the two laser spots of the remelting laser 6 and the impact laser 4 to be 6 mm. Step 3: Place the workpiece to be strengthened in the atmosphere protection chamber 7, and introduce high-purity argon gas through the protective gas inlet 5. Taking advantage of the fact that argon gas is denser than air, the air in the chamber is discharged through the small gap reserved on the upper side until the oxygen concentration in the atmosphere protection chamber drops below 200 ppm; Step four: Turn on the remelting laser 6 and scan the workpiece surface along a preset trajectory, causing its surface layer to melt instantly and form a microscopic molten pool 8. The remelting laser 6 has a power of 3000 W and a scanning speed of 300 mm / min. Subsequently, ultra-fast solidification is completed under the rapid heat conduction of the substrate. Step 5: With the relative positions of the remelting laser and the shock laser fixed, the solid phase region that is still at high temperature after remelting is precisely moved to the spot of the shock laser by the moving platform 10, and laser shock strengthening is performed immediately. The shock laser 4 has an energy of 3 J, a frequency of 10 Hz, and is at a 60° angle to the surface of the workpiece to be strengthened. Step six: After the strengthening process is completed, the workpiece is cooled to room temperature in a protective chamber with argon gas continuously supplied to ensure that it is not oxidized during the cooling process.

[0083] Compared to Example 5, the scanning speed of Comparative Example 5 was reduced from 450 mm / min to 300 mm / min. Although the overlap rate of the impact spot increased from 81.25% to 87.5%, the excessively low scanning speed increased the remelting heat input, resulting in surface ablation and grain coarsening. The average hardness of the reinforced layer after this process was approximately 544 HV, and the wear volume was 0.2711 mm. 3 The wear type is fatigue wear. Comparative Example 6

[0084] The in-situ synchronous surface strengthening method of 38CrMoAl alloy steel by laser remelting and impact includes the following steps: Step 1: Grind and polish the parts of the 38CrMoAl alloy steel (composition same as in Example 1) to be strengthened, and clean with acetone to thoroughly remove surface oil, dust and other impurities. Step two: Based on the size and shape of the reinforced surface, the movement path of the moving platform 10 is set through the movement control module, and the two-dimensional scanning trajectories of the remelting laser and the shock laser are planned. The position of the shock laser is fixed, and the remelting laser equipment is adjusted by the robotic arm to precisely control the center distance between the two laser spots of the remelting laser 6 and the shock laser 4 to be 4 mm. Step 3: Connect the workpiece to be strengthened to a thermocouple thermometer for real-time temperature measurement and place it in the atmosphere protection chamber 7. Introduce high-purity argon gas through the protective gas inlet 5. Utilizing the property that argon gas is denser than air, exhaust the air in the chamber through the small gap reserved on the upper side until the oxygen concentration in the atmosphere protection chamber drops below 200 ppm. Step four: Turn on the remelting laser 6 and scan the workpiece surface along a preset trajectory, causing its surface layer to melt instantly and form a microscopic molten pool 8. The remelting laser 6 has a power of 3000 W and a scanning speed of 600 mm / min. Subsequently, ultra-fast solidification is completed under the rapid heat conduction of the substrate. Step 5: With the relative positions of the remelting laser and the shock laser fixed, the solid phase region that is still at high temperature after remelting is precisely moved to the spot of the shock laser by the moving platform 10, and laser shock strengthening is performed immediately. The shock laser 4 has an energy of 3 J, a frequency of 10 Hz, and is at a 60° angle to the surface of the workpiece to be strengthened. Step six: After the strengthening process is completed, the workpiece is cooled to room temperature in a protective chamber with argon gas continuously supplied to ensure that it is not oxidized during the cooling process.

[0085] When the distance between the two lasers is less than 4 mm, the pulsed laser will act on both the molten pool and the high-temperature solid region simultaneously, thus weakening the strengthening effect on the high-temperature solid region. Compared with Example 6, the distance between the remelting laser and the impact laser in Comparative Example 6 was adjusted from 4.5 mm to 4 mm. The temperature range of the impact site is approximately 850 ℃-1210 ℃. Due to the high temperature at this impact site, beneficial defects such as dislocations generated after the impact will disappear due to recrystallization, thus weakening the strengthening effect. Furthermore, the high temperature corresponds to a lower plastic strain limit surface of the material, and the impact will make the surface more prone to deformation, resulting in excessive roughness. The average hardness of the strengthened layer after this process is approximately 511 HV, the contact fatigue strength is reduced to 1774.3 MPa, and the wear volume is 0.3395 mm. 3 The wear types are abrasive wear and a small amount of adhesive wear. Comparative Example 7

[0086] The in-situ synchronous surface strengthening method of 38CrMoAl alloy steel by laser remelting and impact includes the following steps: Step 1: Grind and polish the parts of the 38CrMoAl alloy steel (composition same as in Example 1) to be strengthened, and clean with acetone to thoroughly remove surface oil, dust and other impurities. Step two: Based on the size and shape of the reinforced surface, the movement path of the moving platform 10 is set through the movement control module, and the two-dimensional scanning trajectories of the remelting laser and the shock laser are planned. The position of the shock laser is fixed, and the remelting laser equipment is adjusted by the robotic arm to precisely control the center distance between the two laser spots of the remelting laser 6 and the shock laser 4 to be 8 mm. Step 3: Connect the workpiece to be strengthened to a thermocouple temperature sensor for real-time temperature measurement and place it in the atmosphere protection chamber 8. Introduce high-purity argon gas through the protective gas inlet 5. Utilizing the property that argon gas is denser than air, exhaust the air in the chamber through the small gap reserved on the upper side until the oxygen concentration in the atmosphere protection chamber drops below 200 ppm. Step four: Turn on the remelting laser 6 and scan the workpiece surface along a preset trajectory, causing its surface layer to melt instantly and form a microscopic molten pool 8. The remelting laser 6 has a power of 3000 W and a scanning speed of 600 mm / min. Subsequently, ultra-fast solidification is completed under the rapid heat conduction of the substrate. Step 5: With the relative positions of the remelting laser and the shock laser fixed, the solid phase region that is still at high temperature after remelting is precisely moved to the spot of the shock laser by the moving platform 10, and laser shock strengthening is performed immediately. The shock laser 4 has an energy of 3 J, a frequency of 10 Hz, and is at a 60° angle to the surface of the workpiece to be strengthened. Step six: After the strengthening process is completed, the workpiece is cooled to room temperature in a protective chamber with argon gas continuously supplied to ensure that it is not oxidized during the cooling process.

[0087] Compared to Example 7, the distance between the remelting laser and the impact laser in Comparative Example 7 was adjusted from 7.5 mm to 8 mm, and the temperature range of the impact site was approximately 440 ℃-680 ℃. Due to the greater distance between the two lasers, the temperature of the pulsed laser's impact site was lower, and the corresponding material plastic strain limit was higher at this temperature. The impact force of the pulsed laser could only cause elastic deformation in localized areas of the material surface and could not produce an elastic effect. The average hardness of the reinforced layer after this process was approximately 488 HV, the contact fatigue strength decreased to 1688.8 MPa, and the wear volume was 0.3671 mm. 3 The wear types are abrasive wear and adhesive wear. Comparative Example 8

[0088] The in-situ synchronous surface strengthening method of 38CrMoAl alloy steel by laser remelting and impact includes the following steps: Step 1: Grind and polish the parts of the 38CrMoAl alloy steel (composition same as in Example 1) to be strengthened, and clean with acetone to thoroughly remove surface oil, dust and other impurities. Step two: Based on the size and shape of the reinforced surface, the movement path of the moving platform 10 is set through the movement control module, and the two-dimensional scanning trajectories of the remelting laser and the impact laser are planned. The position of the impact laser is fixed, and the remelting laser equipment is adjusted by the robotic arm to precisely control the center distance between the two laser spots of the remelting laser 6 and the impact laser 4 to be 6 mm. Step 3: Place the workpiece to be strengthened in the atmosphere protection chamber 7, and introduce high-purity argon gas through the protective gas inlet 5. Taking advantage of the fact that argon gas is denser than air, the air in the chamber is discharged through the small gap reserved on the upper side until the oxygen concentration in the atmosphere protection chamber drops below 200 ppm; Step four: Turn on the remelting laser 6 and scan the workpiece surface along a preset trajectory, causing its surface layer to melt instantly and form a microscopic molten pool 8. The remelting laser 6 has a power of 3000 W and a scanning speed of 600 mm / min. Subsequently, ultra-fast solidification is completed under the rapid heat conduction of the substrate. Step 5: With the relative positions of the remelting laser and the shock laser fixed, the solid phase region that is still at high temperature after remelting is precisely moved to the spot of the shock laser by the moving platform 10, and laser shock strengthening is performed immediately. The shock laser 4 has an energy of 1.5 J, a frequency of 10 Hz, and is at a 60° angle to the surface of the workpiece to be strengthened. Step six: After the strengthening process is completed, the workpiece is cooled to room temperature in a protective chamber with argon gas continuously supplied to ensure that it is not oxidized during the cooling process.

[0089] Compared to Example 8, Comparative Example 8 reduced the impact energy of the shock laser from 2 J to 1.5 J. The average hardness of the reinforced layer after this process was approximately 517 HV, and the wear volume was 0.3549 mm. 3 The wear types are abrasive wear and a small amount of adhesive wear. After the impact energy decreases, the shock wave reaches the plastic strain limit threshold corresponding to the temperature of that part, which is insufficient to overcome the dynamic yield strength of the material to induce effective plastic deformation or to generate dislocation multiplication and promote heterogeneous nucleation internally, thus weakening the strengthening effect on the material surface. Comparative Example 9

[0090] The in-situ synchronous surface strengthening method of 38CrMoAl alloy steel by laser remelting and impact includes the following steps: Step 1: Grind and polish the parts of the 38CrMoAl alloy steel (composition same as in Example 1) to be strengthened, and clean with acetone to thoroughly remove surface oil, dust and other impurities. Step two: Based on the size and shape of the reinforced surface, the movement path of the moving platform 10 is set through the movement control module, and the two-dimensional scanning trajectories of the remelting laser and the impact laser are planned. The position of the impact laser is fixed, and the remelting laser equipment is adjusted by the robotic arm to precisely control the center distance between the two laser spots of the remelting laser 6 and the impact laser 4 to be 6 mm. Step 3: Place the workpiece to be strengthened in the atmosphere protection chamber 7, and introduce high-purity argon gas through the protective gas inlet 5. Taking advantage of the fact that argon gas is denser than air, the air in the chamber is discharged through the small gap reserved on the upper side until the oxygen concentration in the atmosphere protection chamber drops below 200 ppm; Step four: Turn on the remelting laser 6 and scan the workpiece surface along a preset trajectory, causing its surface layer to melt instantly and form a microscopic molten pool 8. The remelting laser 6 has a power of 3000 W and a scanning speed of 600 mm / min. Subsequently, ultra-fast solidification is completed under the rapid heat conduction of the substrate. Step 5: With the remelting laser and the shock laser in fixed relative positions, the solid phase region that is still at high temperature after remelting is precisely moved to the shock laser spot by the moving platform 10, and laser shock strengthening is performed immediately. The shock laser 4 has an energy of 4 J, a frequency of 10 Hz, and is at a 60° angle to the surface of the workpiece to be strengthened. Step six: After the strengthening process is completed, the workpiece is cooled to room temperature in a protective chamber with argon gas continuously supplied to ensure that it is not oxidized during the cooling process.

[0091] Compared to Example 9, Comparative Example 9 increased the impact energy of the shock laser 4 from 3.5 J to 4 J. The average hardness of the reinforced layer after this process was approximately 503 HV, and the wear volume was 0.3401 mm. 3 The wear types are fatigue wear and a small amount of abrasive wear. Excessive laser shock energy can cause the process to shift from beneficial plastic strengthening to harmful surface damage, and may weaken the strengthening effect due to the induction of residual stress relaxation and macroscopic deformation. Comparative Example 10

[0092] The in-situ synchronous surface strengthening method of 38CrMoAl alloy steel by laser remelting and impact includes the following steps: Step 1: Grind and polish the parts of the 38CrMoAl alloy steel (composition same as in Example 1) to be strengthened, and clean with acetone to thoroughly remove surface oil, dust and other impurities. Step two: Based on the size and shape of the reinforced surface, the movement path of the moving platform 10 is set through the movement control module, and the two-dimensional scanning trajectories of the remelting laser and the impact laser are planned. The position of the impact laser is fixed, and the remelting laser equipment is adjusted by the robotic arm to precisely control the center distance between the two laser spots of the remelting laser 6 and the impact laser 4 to be 6 mm. Step 3: Place the workpiece to be strengthened in the atmosphere protection chamber 7, and introduce high-purity argon gas through the protective gas inlet 5. Taking advantage of the fact that argon gas is denser than air, the air in the chamber is discharged through the small gap reserved on the upper side until the oxygen concentration in the atmosphere protection chamber drops below 200 ppm; Step four: Turn on the remelting laser 6 and scan the workpiece surface along a preset trajectory, causing its surface layer to melt instantly and form a microscopic molten pool 8. The remelting laser 6 has a power of 3000 W and a scanning speed of 600 mm / min. Subsequently, ultra-fast solidification is completed under the rapid heat conduction of the substrate. Step 5: With the relative positions of the remelting laser and the shock laser fixed, the solid phase region that is still at high temperature after remelting is precisely moved to the spot of the shock laser by the moving platform 10, and laser shock strengthening is performed immediately. The shock laser 4 has an energy of 3 J, a frequency of 10 Hz, and is at a 30° angle to the surface of the workpiece to be strengthened. Step six: After the strengthening process is completed, the workpiece is cooled to room temperature in a protective chamber with argon gas continuously supplied to ensure that it is not oxidized during the cooling process.

[0093] Compared to Example 10, Comparative Example 10 adjusted the angle between the pulsed laser and the surface of the reinforced material from 45° to 30°. The reinforced layer treated by this process had an average hardness of approximately 547 HV and a wear volume of 0.2910 mm. 3 The wear type is fatigue wear. An excessively small angle reduces energy absorption and vertical impact force, decreasing the strength and depth of the strengthening effect. Furthermore, due to the increased radial impact force, the molten pool fluctuates under the influence of vibration transmission, leaving a "wave"-like surface texture during solidification, reducing surface smoothness. Comparative Example 11

[0094] The in-situ synchronous surface strengthening method of 38CrMoAl alloy steel by laser remelting and impact includes the following steps: Step 1: Grind and polish the parts of the 38CrMoAl alloy steel (composition same as in Example 1) to be strengthened, and clean with acetone to thoroughly remove surface oil, dust and other impurities. Step two: Based on the size and shape of the reinforced surface, the movement path of the moving platform 10 is set through the movement control module, and the two-dimensional scanning trajectories of the remelting laser and the impact laser are planned. The position of the impact laser is fixed, and the remelting laser equipment is adjusted by the robotic arm to precisely control the center distance between the two laser spots of the remelting laser 6 and the impact laser 4 to be 6 mm. Step 3: Place the workpiece to be strengthened in the atmosphere protection chamber 7, and introduce high-purity argon gas through the protective gas inlet 5. Taking advantage of the fact that argon gas is denser than air, the air in the chamber is discharged through the small gap reserved on the upper side until the oxygen concentration in the atmosphere protection chamber drops below 200 ppm; Step four: Turn on the remelting laser 6 and scan the workpiece surface along a preset trajectory, causing its surface layer to melt instantly and form a microscopic molten pool 8. The remelting laser 6 has a power of 3000 W and a scanning speed of 600 mm / min. Subsequently, ultra-fast solidification is completed under the rapid heat conduction of the substrate. Step 5: With the remelting laser and the shock laser in fixed relative positions, the solid phase region that is still at high temperature after remelting is precisely moved to the shock laser spot by the moving platform 10, and laser shock strengthening is performed immediately. The shock laser 4 has an energy of 3 J, a frequency of 5 Hz, and is at a 60° angle to the surface of the workpiece to be strengthened. Step six: After the strengthening process is completed, the workpiece is cooled to room temperature in a protective chamber with argon gas continuously supplied to ensure that it is not oxidized during the cooling process.

[0095] Compared to Example 11, Comparative Example 11 reduced the pulsed laser impact frequency from 7 Hz to 5 Hz. The average hardness of the reinforced layer after this process was approximately 508 HV, and the wear volume was 0.4937 mm. 3 The wear types are adhesive wear and abrasive wear. The decrease in impact frequency disrupts the uniformity of the reinforced layer and the continuity of the in-situ synchronous effect. This causes the surface properties and microstructure of the reinforced layer to degrade from a continuous, uniform distribution to a discrete, island-like distribution, forming unreinforced zones within the impact intervals, significantly impacting the material's wear performance and reliability. Comparative Example 12

[0096] The in-situ synchronous surface strengthening method of 38CrMoAl alloy steel by laser remelting and impact includes the following steps: Step 1: Grind and polish the parts of the 38CrMoAl alloy steel (composition same as in Example 1) to be strengthened, and clean with acetone to thoroughly remove surface oil, dust and other impurities. Step two: Based on the size and shape of the reinforced surface, the movement path of the moving platform 10 is set through the movement control module, and the two-dimensional scanning trajectories of the remelting laser and the impact laser are planned. The position of the impact laser is fixed, and the remelting laser equipment is adjusted by the robotic arm to precisely control the center distance between the two laser spots of the remelting laser 6 and the impact laser 4 to be 6 mm. Step 3: Place the workpiece to be strengthened in the atmosphere protection chamber 7, and introduce high-purity argon gas through the protective gas inlet 5. Taking advantage of the fact that argon gas is denser than air, the air in the chamber is discharged through the small gap reserved on the upper side until the oxygen concentration in the atmosphere protection chamber drops below 200 ppm; Step four: Turn on the remelting laser 6 and scan the workpiece surface along a preset trajectory, causing its surface layer to melt instantly and form a microscopic molten pool 8. The remelting laser 6 has a power of 3000 W and a scanning speed of 600 mm / min. Subsequently, ultra-fast solidification is completed under the rapid heat conduction of the substrate. Step 5: With the relative positions of the remelting laser and the shock laser fixed, the solid phase region that is still at high temperature after remelting is precisely moved to the spot of the shock laser by the moving platform 10, and laser shock strengthening is performed immediately. The shock laser 4 has an energy of 3 J and a frequency of 12 Hz, and forms a 60° angle with the surface of the workpiece 9 to be strengthened. Step six: After the strengthening process is completed, the workpiece is cooled to room temperature in a protective chamber with argon gas continuously supplied to ensure that it is not oxidized during the cooling process.

[0097] Compared to Example 1, Comparative Example 12 increased the pulsed laser impact frequency from 10 Hz to 12 Hz. The average hardness of the reinforced layer after this process was approximately 549 HV, and the wear volume was 0.2919 mm. 3 The wear type is fatigue. When the impact frequency increases to the threshold, excessive plastic deformation and stress field interference due to excessive overlap will cause excessive mechanical damage to the remelted structure.

[0098] In the foregoing description of exemplary embodiments of the invention, various features of the invention are sometimes grouped together in a single embodiment, figure, or description thereof. However, this disclosure should not be construed as reflecting an intention that the claimed invention requires more features than expressly recited in each claim. Rather, as reflected in the claims, the inventive aspect lies in fewer than all features of the foregoingly disclosed embodiments. Therefore, the claims, following the detailed description, are hereby expressly incorporated into that detailed description, wherein each claim itself is a separate embodiment of the invention.

[0099] Although the invention has been described with reference to a limited number of embodiments, those skilled in the art will understand from the foregoing description that other embodiments are conceivable within the scope of the invention described herein. Furthermore, it should be noted that the language used in this specification has been chosen primarily for readability and instructional purposes, and not for the purpose of interpreting or limiting the subject matter of the invention. Therefore, many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the appended claims. The disclosure of the invention is illustrative and not restrictive, and the scope of the invention is defined by the appended claims.

[0100] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for in-situ synchronous surface strengthening of 38CrMoAl alloy steel using laser remelting-laser shock oscillation, characterized in that, Includes the following steps: Step 1: Clean the 38CrMoAl alloy steel parts to be strengthened. Step 2: Plan the two-dimensional scanning trajectories of the remelting laser and the shock laser, fix the position of the shock laser, adjust the remelting laser, and control the center distance between the two laser spots of the remelting laser and the shock laser to be 4.5-7.5mm; Step 3: Place the 38CrMoAl alloy steel in the atmosphere protection chamber and introduce high-purity argon gas through the protective gas inlet on the atmosphere protection chamber. Air is exhausted from the atmosphere protection chamber through the pre-reserved gap on the upper side until the oxygen concentration in the atmosphere protection chamber drops below 200 ppm. Step four: Activate the remelting laser and scan the surface of the 38CrMoAl alloy steel according to the planned two-dimensional scanning trajectory. The remelting laser power is 2000-4400 W, and the scanning speed is 450-1050 mm / min, causing the surface layer of the 38CrMoAl alloy steel to melt instantly and form a molten pool. Subsequently, under the action of the 38CrMoAl alloy steel's own cold matrix, its cooling rate reaches 10. 3 -10 5 ℃ / s, enabling the molten pool to solidify rapidly within 100-500 ms; Step 5: With the relative positions of the remelting laser and the shock laser fixed, move the 38CrMoAl alloy steel, which is still in the high-temperature solid phase region after remelting, to the shock laser spot and immediately perform laser shock strengthening. The shock laser energy is 2-3.5 J, the shock frequency is 7-10 Hz, and the angle between the shock laser and the surface of the 38CrMoAl alloy steel is 45-90°. Step six: After the strengthening process is completed, the 38CrMoAl alloy steel is cooled to room temperature in a protective chamber with argon gas continuously introduced, thus obtaining the strengthened 38CrMoAl alloy steel.

2. The method according to claim 1, characterized in that, In step one, the cleaning process involves grinding and polishing, followed by cleaning with acetone to thoroughly remove surface oil and dust.

3. The method according to claim 1, characterized in that, In step two, the two-dimensional scanning trajectory is a unidirectional parallel scanning path; both the remelting laser and the shock laser are circular spots with a diameter of 4 mm.

4. The method according to claim 1, characterized in that, In step five, the temperature range of the high-temperature solid phase region is 580-1090 ℃.

5. The method according to claim 1, characterized in that, In step five, the impact laser and the remelting laser travel the same path.

6. The method according to claim 1, characterized in that, The chemical composition of 38CrMoAl alloy steel, by mass percentage, includes: 0.35%≤C≤0.42%; 0.2%≤Si≤0.45%; 0.3%≤Mn≤0.6%; 1.35%≤Cr≤1.65%; 0.7%≤Al≤1.1%; 0.15%≤Mo≤0.25%; the remainder is iron and unavoidable impurities during the production process.

7. The strengthened 38CrMoAl alloy steel obtained by the method according to any one of claims 1 to 6, characterized in that, The average hardness of its reinforced layer is 556-690 HV; the wear volume is 0.1375-0.3097 mm. 3 The fatigue strength is 2017.9-2219.4 MPa.

8. The application of the reinforced 38CrMoAl alloy steel according to claim 7 in key load-bearing components in precision machine tools, aerospace, and chemical industries, characterized in that, Key load-bearing components include high-precision machine tool spindles and ball screws, aircraft landing gear actuators, and high-pressure chemical valve stems.

9. A key load-bearing component, characterized in that, It is prepared from the reinforced 38CrMoAl alloy steel as described in claim 8.

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