Corrosion-resistant nickel-based alloy and preparation process thereof

Abstract

The invention relates to the technical field of alloy preparation, in particular to a corrosion-resistant nickel-based alloy and a preparation process thereof. The technical problem that an existing nickel-based alloy is difficult to consider mechanical properties and corrosion resistance at the same time is solved. The preparation method comprises the following steps: performing vacuum induction melting on multi-element raw materials, and stirring in a low-frequency alternating magnetic field to obtain a casting body; the fluoride slag is subjected to ultrasonic-assisted electroslag remelting treatment, and a remelted ingot is obtained; performing isothermal multidirectional forging and liquid nitrogen cooling to obtain a forged body; carrying out solid solution and double-stage aging treatment to obtain a semi-finished alloy; and carrying out laser shock peening treatment on the semi-finished alloy to obtain the corrosion-resistant nickel-based alloy. Through the synergistic effect of multiple processes, grains are refined, grain boundaries and precipitated phases are optimized, meanwhile, a deep compressive stress layer is constructed on the surface, and the comprehensive strength and corrosion resistance of the alloy are remarkably improved.

Description

Technical Field

[0001] This invention relates to the field of alloy preparation technology, specifically to a corrosion-resistant nickel-based alloy and its preparation process. Background Technology

[0002] Nickel-based alloys are indispensable core materials in modern industry due to their excellent thermal stability and good comprehensive mechanical properties at extreme temperatures. As a typical nickel-based corrosion-resistant alloy, it relies primarily on elements such as chromium (Cr), molybdenum (Mo), and tungsten (W) dissolved in the matrix to spontaneously form an extremely dense oxide passivation film on the material surface. This passivation film provides excellent chemical protection under harsh operating conditions and is widely used in chemical reactors, marine engineering, and heat transfer tubes in nuclear power steam generators.

[0003] Despite the widespread application of traditional nickel-based alloys, the industry currently faces a serious technical bottleneck: the difficulty in simultaneously achieving both corrosion resistance and mechanical properties. On the one hand, to cope with increasingly harsh corrosive environments, the traditional approach is often to increase the content of corrosion-resistant elements such as Cr, Mo, and W. However, during high-temperature service or welding thermal cycling, these high-content alloying elements are prone to precipitating large amounts of brittle topologically close-packed phases (TCP phases, such as σ phase and μ phase) at grain boundaries. The precipitation of these harmful phases not only removes a large amount of corrosion-resistant elements from the matrix, leading to "chromium-depleted / molybdenum-depleted zones" around the grain boundaries, causing severe local pitting corrosion and intergranular corrosion, resulting in poor corrosion resistance, but also, the TCP phase itself is hard and brittle, which can disrupt the continuity of the matrix and, as a crack initiation, significantly reduce the alloy's room-temperature plasticity, yield strength, and high-temperature creep fatigue life, resulting in poor mechanical properties.

[0004] To address this, a corrosion-resistant nickel-based alloy and its preparation process are proposed. Summary of the Invention

[0005] The purpose of this invention is to design a corrosion-resistant nickel-based alloy and its preparation process. This invention involves vacuum induction melting of multi-element raw materials, supplemented by low-frequency alternating magnetic field stirring to obtain a cast body; ultrasonic-assisted electroslag remelting of fluoride slag to obtain a remelted ingot; isothermal multi-directional forging and liquid nitrogen cooling to obtain a forged body; solution treatment and two-stage aging treatment to obtain a semi-finished alloy; and laser shock peening treatment to obtain a corrosion-resistant nickel-based alloy. This invention, through the synergistic effect of multiple processes, refines the grains and optimizes grain boundaries and precipitates, while simultaneously constructing a deep compressive stress layer on the surface, significantly improving the overall strength and corrosion resistance of the alloy.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] This invention provides a process for preparing a corrosion-resistant nickel-based alloy, comprising the following steps:

[0008] Electrolytic nickel plates, molybdenum bars, nickel-tantalum master alloys, ruthenium briquettes, nickel-tungsten master alloys, nickel-niobium master alloys, high-purity titanium wires, aluminum granules, and nickel-yttrium master alloys are subjected to vacuum induction melting and then cast to obtain a casting.

[0009] Using fluoride slag, the casting body is subjected to ultrasonic-assisted electroslag treatment to obtain a remelted ingot;

[0010] The remelted ingot is subjected to isothermal multi-directional forging and liquid nitrogen cooling to obtain a forged body;

[0011] The forged body undergoes solution treatment and two-stage aging treatment to obtain a semi-finished alloy; the semi-finished alloy undergoes laser shock strengthening treatment to obtain a corrosion-resistant nickel-based alloy.

[0012] Preferably, the specific process of vacuum induction melting is as follows: A crucible is tamped with high-purity alumina and the furnace is dried. Electrolytic nickel plates, molybdenum bars, nickel-tantalum master alloy (containing 60% tantalum), ruthenium briquettes, and nickel-tungsten master alloy (containing 60% tungsten) are placed in the crucible, and a vacuum is drawn to below 0.1 Pa in a cold state. Electricity is supplied to raise the temperature, and after the base material has completely melted, a nickel-niobium master alloy (containing 60% niobium) is added, with the temperature controlled at 1540℃-1570℃. Subsequently, the vacuum degree is increased to 1.0 × 10⁻⁶. -3 Pa, heat to 1580℃ and hold for 30 min. During this stage, turn on the electromagnetic stirrer and apply a low-frequency pulsed alternating magnetic field with a frequency of 50 Hz and a magnetic induction intensity of 0.08 T. 5 min before tapping, purge with high-purity argon to a slightly negative pressure state (absolute pressure of about 80000 Pa) to suppress volatilization. Then, quickly add high-purity titanium wire, aluminum granules and nickel-yttrium master alloy (containing 70% yttrium), stir evenly to obtain a molten alloy, and cast at 1480℃-1500℃ to obtain a casting. The content of each metal element in the molten alloy is: Mo: 20%-22%, Ta: 6%-8%, W: 3%-4%, Nb: 1-3%, Ti: 1-2%, Al: 0.5-1.5%, Ru: 0.5%-1%, Y: 0.05%-0.1%, with the balance being Ni.

[0013] Preferably, the specific process of ultrasonic-assisted electroslag remelting is as follows: a pre-melted fluoride slag material is used: 70% CaF2 + 20% Al2O3 + 10% CaO; before remelting, the slag material needs to be calcined at 780℃-820℃ for 4 hours to dehydrate; AC power is used, the melting current is stabilized at 3500A, and the voltage is 50V; the melting rate is controlled at 4-5kg / min, a shallow and flat molten pool is maintained, and high-energy ultrasonic waves are applied to the bottom pad of the water-cooled copper crystallizer with a frequency of 20kHz, an output power of 2000W, and an amplitude of 15μm to obtain a remelted ingot.

[0014] Preferably, the specific process of isothermal multi-directional forging and liquid nitrogen cooling is as follows: after the remelted ingot is surface-finished, it is placed in a heating furnace and heated to 1160℃-1180℃ at a heating rate of 10℃ / min, and held at this temperature for 4 hours to homogenize the microstructure; then, three-dimensional multi-directional upsetting (alternating compression along the XYZ axes) is performed on a press with mold heating function, and the strain rate is strictly controlled at 0.01s. -1 -0.1s -1 Within a certain range, the single-pass pressing amount is about 20%, and the total deformation reaches more than 80%. After final forging, it is quenched in water to room temperature within 15 seconds (to retain high-density dislocations), wiped dry, and then immersed in a liquid nitrogen tank at -196℃ (pre-cooled with gaseous nitrogen for 2 hours) and held at that temperature for 22-26 hours to obtain the forging body.

[0015] Preferably, the specific process of solution treatment and two-stage aging treatment is as follows: the forging is heated to 1080℃-1120℃ and held for 2 hours; then the first-stage aging treatment is performed: the temperature is raised to 720℃ and held for 7-9 hours. After the holding is completed, instead of air cooling, it is cooled in the furnace at a slow cooling rate of 50℃ / h to the second aging temperature. The second-stage aging treatment is performed: the temperature is lowered to 600℃-640℃ and held for 8 hours. Then it is directly removed from the furnace and air cooled to room temperature to obtain a semi-finished alloy.

[0016] Preferably, the specific process of laser shock strengthening treatment is as follows: a 0.1 mm thick black tape (polyvinyl chloride, absorption layer) is attached to the surface of the semi-finished alloy, and covered with a 1.5 mm thick layer of flowing pure water (constraint layer); an Nd:YAG nanosecond pulsed laser with a wavelength of 1064 nm, a pulse width of 15 ns, a spot diameter of 2 mm, a laser power density of 7 GW / cm², and an overlap rate of 50% is used to perform multi-pass gridded scanning to induce the generation of a stress layer on the surface, and finally obtain a corrosion-resistant nickel-based alloy.

[0017] Another aspect of the present invention provides a corrosion-resistant nickel-based alloy, the raw materials of which include electrolytic nickel plates, molybdenum bars, nickel-tantalum master alloys, ruthenium briquettes, nickel-tungsten master alloys, nickel-niobium master alloys, high-purity titanium wires, aluminum granules, and nickel-yttrium master alloys.

[0018] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0019] 1. The alloy contains high levels of Mo (20%-22%), Ta, W, and the precious metal Ru. These elements are not only excellent corrosion-resistant elements but also provide strong solid solution strengthening effects. Rare earth Y is also added to purify grain boundaries. During the smelting stage, a low-frequency pulsed alternating magnetic field is introduced for electromagnetic stirring, effectively breaking the compositional segregation of refractory heavy metal elements and ensuring a high degree of uniformity in the ingot's chemical composition. This allows the alloy to exhibit both excellent matrix strength and comprehensive corrosion resistance on a macroscopic scale.

[0020] 2. Using specific fluoride slag materials allows for deep deoxidation and impurity removal, significantly reducing the number of non-metallic inclusions in the alloy, thereby eliminating the initiation source of localized pitting corrosion and greatly enhancing corrosion resistance. Simultaneously, applying high-energy ultrasonic waves at the bottom utilizes ultrasonic cavitation and acoustic flow effects to break up coarse dendrites, refining the solidification structure and eliminating casting defects such as shrinkage cavities. This pure and dense fine-grained structure makes the alloy less prone to crack initiation under high mechanical loads, achieving a balance between high toughness and high corrosion resistance.

[0021] 3. After homogenization, three-dimensional multi-directional upsetting and drawing are performed, with a total deformation of over 80%, achieving extreme grain refinement. Following final forging, rapid water quenching preserves high-density dislocations, followed by prolonged liquid nitrogen cryogenic treatment at -196℃. This process not only further stabilizes the matrix structure and eliminates harmful macroscopic residual tensile stresses generated during forging, but also provides ample nucleation sites for the uniform precipitation of subsequent nanoscale strengthening phases. This allows the alloy to maintain extremely high mechanical properties while retaining an excellent corrosion-resistant matrix.

[0022] 4. Unlike conventional air-cooling interruption, this invention employs a slow cooling rate of 50℃ / h to transition to the second aging stage after the first aging. This unique temperature control path promotes the dense distribution of strengthening phases such as γ' and γ'' in a dual-state or multi-scale manner, maximizing the precipitation strengthening effect to ensure excellent mechanical properties. Simultaneously, this slow cooling process effectively suppresses the continuous network precipitation of carbides and brittle phases at grain boundaries, avoiding the formation of chromium / molybdenum-poor regions at grain boundaries, thereby completely blocking the pathway for intergranular corrosion.

[0023] 5. High-power-density nanosecond lasers are used to bombard the surface of semi-finished alloys, inducing a high-amplitude residual compressive stress layer on the surface, accompanied by nano-sized surface grains. This compressive stress layer not only significantly improves the mechanical properties of the alloy, but more importantly, it effectively closes surface microcracks, greatly enhancing the stability of the passivation film. This effectively inhibits the initiation and propagation of stress corrosion cracks in harsh corrosive environments, achieving a unified top-level design for both mechanical and chemical resistance. Attached Figure Description

[0024] Figure 1 The diagram shows the Vickers hardness and corrosion resistance of Examples 1-5 and Comparative Examples 1-4 in this invention. Detailed Implementation

[0025] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0026] For details, please refer to [link / reference]. Figure 1 This invention provides a corrosion-resistant nickel-based alloy and its preparation process, the technical solution of which is as follows:

[0027] Example 1

[0028] The crucible was tamped with high-purity alumina and the furnace was dried. Electrolytic nickel plates, molybdenum bars, nickel-tantalum master alloy, ruthenium briquettes, and nickel-tungsten master alloy were placed in the crucible, and a vacuum was drawn to below 0.1 Pa in a cold state. Power was applied to raise the temperature, and after the base material was completely melted, a nickel-niobium master alloy was added, with the temperature controlled at 1560℃. Subsequently, the vacuum was increased to 1.0 × 10⁻⁶ Pa. -3 Pa, heat to 1580℃ and hold for 30 min. During this stage, turn on the electromagnetic stirrer and apply a low-frequency pulsed alternating magnetic field with a frequency of 50 Hz and a magnetic induction intensity of 0.08 T. 5 min before tapping, purge with high-purity argon to a slightly negative pressure state (absolute pressure of about 80000 Pa) to suppress volatilization. Then, quickly add high-purity titanium wire, aluminum granules and nickel-yttrium master alloy, stir evenly to obtain a molten alloy, and cast at 1490℃ to obtain a casting. The content of each metal element in the molten alloy is: Mo: 21%, Ta: 7%, W: 3.5%, Nb: 2%, Ti: 1.5%, Al: 1%, Ru: 0.8%, Y: 0.08%, with the balance being Ni.

[0029] Pre-melted fluoride slag material is used: 70% CaF2 + 20% Al2O3 + 10% CaO; the slag material needs to be roasted at 800℃ for 4 hours to dehydrate before remelting; AC power is used, the melting current is stabilized at 3500A, and the voltage is 50V; the melting rate is controlled at 4.5kg / min, and a shallow and flat molten pool is maintained. High-energy ultrasonic waves are applied to the bottom pad of the water-cooled copper crystallizer with a frequency of 20kHz, an output power of 2000W, and an amplitude of 15μm to obtain remelted ingots;

[0030] After surface finishing, the remelted ingot is placed in a heating furnace and heated to 1170℃ at a heating rate of 10℃ / min, and held at that temperature for 4 hours to homogenize the microstructure. Then, it undergoes three-dimensional multi-directional upsetting (alternating compression along the XYZ axes) on a press with mold heating function, with the strain rate strictly controlled at 0.01s. -1 -0.1s -1 Within this range, the single-pass pressing amount is about 20%, and the total deformation amount reaches more than 80%. After final forging, it is quenched in water to room temperature within 15 seconds (to retain high-density dislocations), wiped dry, and then immersed in a liquid nitrogen tank at -196℃ (pre-cooled with gaseous nitrogen for 2 hours) and held at this temperature for 24 hours to obtain the forging body.

[0031] The forged body was heated to 1100℃ and held for 2 hours; then the first aging treatment was carried out: the temperature was raised to 720℃ and held for 8 hours. After the holding was completed, instead of air cooling, it was cooled in the furnace to the second aging temperature at a slow cooling rate of 50℃ / h. The second aging treatment was carried out: the temperature was lowered to 620℃ and held for 8 hours. Then it was directly taken out of the furnace and air cooled to room temperature to obtain a semi-finished alloy.

[0032] A 0.1 mm thick black tape (absorption layer) was attached to the surface of the semi-finished alloy and covered with a 1.5 mm thick layer of flowing pure water (constraint layer). An Nd:YAG nanosecond pulsed laser with a wavelength of 1064 nm, a pulse width of 15 ns, a spot diameter of 2 mm, a laser power density of 7 GW / cm², and an overlap rate of 50% was used to perform multi-pass gridded scanning to induce a stress layer on the surface, ultimately obtaining a corrosion-resistant nickel-based alloy.

[0033] Examples 2-5 refer to the parameter conditions in Example 1, with specific differences shown in Table 1.

[0034]

[0035] Comparative Example 1 follows the same parameters and conditions as in Example 1, except that the low-frequency alternating magnetic field stirring is eliminated during the vacuum induction melting process, while the other steps are the same.

[0036] Comparative Example 2 follows the same parameters and conditions as in Example 1, except that ruthenium briquettes and nickel-yttrium master alloys are not added.

[0037] Comparative Example 3 follows the same parameters and conditions as in Example 1, except that the high-energy ultrasonic assistance is omitted during the ultrasonic-assisted electroslag remelting process, while the other steps are the same.

[0038] Comparative Example 4 follows the same parameters and conditions as in Example 1, except that conventional slag (70% CaF2 + 30% Al2O3) is used instead of fluoride slag.

[0039] Comparative Example 5 uses the same parameters and conditions as in Example 1, except that conventional unidirectional upsetting is used instead of multidirectional forging.

[0040] Comparative Example 6 follows the same parameters and conditions as in Example 1, except that it is air-cooled after final forging (not water-quenched within 15s). The other steps are the same, but it is naturally air-cooled to room temperature after final forging before proceeding with subsequent operations.

[0041] Comparative Example 7 follows the same parameters and conditions as in Example 1, except that liquid nitrogen cooling is not performed, while the other steps are the same.

[0042] Comparative Example 8 follows the same parameters and conditions as in Example 1, except that after the first aging treatment, the furnace is directly removed and air-cooled to room temperature, and then reheated to the temperature of the second aging treatment.

[0043] Comparative Example 9 follows the same parameters and conditions as in Example 1, except that it undergoes single-stage high-temperature aging, and is only kept at 720°C for 8 hours before being air-cooled.

[0044] Comparative Example 10 follows the same parameters and conditions as in Example 1, except that laser shock peening treatment is not performed, while the other steps are the same.

[0045] Comparative Example 11 follows the same parameters and conditions as in Example 1, except that black tape is not attached and flowing pure water is not covered during the laser shock peening treatment, while the other steps are the same.

[0046] Experimental Example 1: Mechanical Properties and Corrosion Resistance Testing

[0047] The Vickers hardness of Examples 1-5 and Comparative Examples 1-4 was tested using a micro Vickers hardness tester (HVS-100 manual turret micro Vickers hardness tester). The loading pressure was 10N and the holding time was 15s. 20 data points were tested and the average value was calculated.

[0048] Referring to GB / T 228.2-2015, the sample was heated to 300℃, held at that temperature for 30 min, and then subjected to a 1×10⁻⁶ ppm precipitate. -3 The strain rate was stretched at a strain rate of / s to test the yield strength of Examples 1-5 and Comparative Examples 1-4.

[0049] The tensile strength of Examples 1-5 and Comparative Examples 1-4 was tested according to GB / T 228.1-2010 standard.

[0050] According to GB / T 10125-2021, the average corrosion rate of Examples 1-5 and Comparative Examples 1-4 was tested in a salt spray formed by NaCl solution (concentration of 50 g / L ± 5 g / L) for a period of 48 hours.

[0051] The results are shown in Table 2. The Vickers hardness and corrosion resistance of Examples 1-5 and Comparative Examples 1-4 are as follows: Figure 1 As shown.

[0052]

[0053] From Table 2 and Figure 1It can be observed that after the low-frequency alternating magnetic field stirring was removed, the tensile strength and yield strength of Comparative Example 1 both decreased, and the average corrosion rate increased significantly. This is because during vacuum induction melting, high-density refractory elements such as Mo, W, and Ta are prone to gravitational segregation and compositional inhomogeneity. The lack of strong stirring effect from electromagnetic stirring prevents solid solution strengthening elements and corrosion-resistant elements from being evenly distributed in the matrix, which not only weakens the macroscopic mechanical properties but also causes local areas to be rapidly corroded by salt spray due to the lack of corrosion-resistant element protection. The mechanical and corrosion resistance properties of Comparative Example 2 decreased the most severely among all comparative groups. Ruthenium (Ru), as a precious metal, provides both strong solid solution strengthening effect and excellent anti-pitting corrosion element. Trace amounts of yttrium (Y) mainly play a role in purifying grain boundaries and improving grain boundary bonding. The absence of ruthenium briquettes and nickel-yttrium master alloys directly leads to a precipitous decrease in the chemical resistance of the matrix to chloride ion corrosion, and because the grain boundaries are not effectively purified and strengthened, the overall hardness and strength of the alloy also deteriorate significantly. Comparative Example 3, without high-energy ultrasonic assistance, had a Vickers hardness reduced to 139.2 HV and its corrosion resistance was inferior to that of the Example. Ultrasonic waves can generate strong cavitation and acoustic flow effects during the electroslag remelting stage. Their core function is to break up coarse dendrites and promote the formation of equiaxed fine grains. The lack of ultrasonic assistance leads to coarse and loose internal crystal structure in the remelted ingot. This coarse grain structure not only makes the material more prone to plastic yielding (reduced strength) when subjected to external forces, but also increases the channels for corrosive media to penetrate along the grain boundaries, resulting in poorer corrosion resistance. After replacing the specially formulated fluoride slag of this invention with conventional slag, the corrosion rate of Comparative Example 4 increased to 0.063 mm / a. The 10% CaO content in the slag of this invention plays a crucial role in deep deoxidation, desulfurization, and impurity removal. The lack of CaO will limit the impurity removal ability during the remelting process, and leave more non-metallic inclusions inside the alloy. These tiny inclusions not only act as stress concentration points when under stress, slightly weakening the mechanical strength, but more fatally, they often become the anode of the micro-electrode galvanic cell in the salt spray environment, thereby inducing local pitting corrosion and significantly reducing the corrosion resistance of the alloy.

[0054] Experiment Example 2: Mechanical Properties and Corrosion Resistance Tests

[0055] The mechanical properties and corrosion resistance of Examples 1-5 and Comparative Examples 5-11 were tested according to the test method of Experimental Example 1, and the results are shown in Table 3.

[0056]

[0057] Table 3 shows that in Comparative Example 5, after using conventional unidirectional upsetting instead of multidirectional forging, the tensile strength of the alloy decreased, and the average corrosion rate increased to 0.045 mm / a. Unidirectional forging causes the grains to be elongated along the deformation direction, forming a significant anisotropic fibrous structure. Unlike three-dimensional multidirectional upsetting, it cannot achieve uniform grain refinement and equiaxed grains. This non-uniform grain structure not only reduces the overall strength of the alloy but also leads to uneven grain boundary distribution, making it easier for corrosive media to penetrate along defective grain boundaries, thus reducing corrosion resistance. In Comparative Example 6, air cooling was used after final forging instead of rapid water quenching within 15 seconds, resulting in a significant decrease in Vickers hardness and tensile strength. Rapid water quenching after forging is intended to freeze and retain the high-density dislocations generated by deformation; while the slow air cooling process leads to the release of deformation energy, dislocation recovery, and annihilation. The sharp reduction in dislocation density directly results in the loss of a large number of nucleation sites for the nano-reinforcing phase during subsequent aging treatment, leading to a reduction in the number and uneven distribution of precipitates, and consequently a significant decrease in macroscopic mechanical properties. In Comparative Example 7, the mechanical properties decreased to some extent after the liquid nitrogen cooling treatment was removed, and the corrosion rate increased significantly to 0.052 mm / a. Liquid nitrogen cryogenic treatment (-196℃) not only further promotes the transformation of retained austenite (or metastable phase), but more importantly, it effectively eliminates the macroscopic residual tensile stress caused by severe plastic deformation and quenching. Without cryogenic treatment, the tensile stress remaining in the matrix will have a synergistic destructive effect with chloride ions in the salt spray corrosion environment, greatly increasing the alloy's susceptibility to stress corrosion cracking. In Comparative Example 8, direct air cooling after the first stage of aging resulted in a surge in the average corrosion rate to 0.095 mm / a. One of the core designs of this invention is a slow cooling transition of 50℃ / h, which effectively inhibits the continuous network precipitation of carbides and other brittle phases at grain boundaries. Direct interruption of air cooling induces the continuous precipitation of harmful phases at grain boundaries and forms a severe chromium / molybdenum-depleted zone near the grain boundaries, which is like opening a high-speed channel for the corrosive medium, triggering severe intergranular corrosion. Comparative Example 9 underwent only single-stage high-temperature aging treatment, resulting in a decrease in both the tensile strength and yield strength of the alloy. Single-stage aging can only induce the precipitation of a single-size strengthening phase (such as the γ' phase). However, the two-stage aging of this invention can induce the strengthening phase to exhibit a dense and dispersed distribution with two states or multiple scales (larger-size phases precipitate at high temperature, and fine secondary phases precipitate at low temperature). The single size and insufficient volume fraction of the strengthening phase cannot effectively hinder dislocation movement, causing the alloy to fail to achieve the expected ultra-high strength. Comparative Example 10, without laser shock stabilization treatment, saw the Vickers hardness of the alloy decrease to 130.5 HV, and the corrosion rate increase to 0.065 mm / a. Laser shock stabilization can induce a high-amplitude residual compressive stress layer on the alloy surface and nanoscale the surface grains, which can not only significantly improve the surface hardness but also forcibly close microcracks on the surface, improving the density and stability of the passivation film. Without this treatment, the alloy surface is directly exposed to corrosive media, resulting in damage to both mechanical resistance and chemical protection.Comparative Example 10, without the application of black tape and the covering of flowing pure water during laser shock, resulted in a severe deterioration in overall performance. The role of pure water is to limit the expansion of laser-induced plasma and forcefully push the explosive shock wave into the material's interior. The black tape is to protect the substrate from direct laser ablation. Without these two, plasma energy dissipates into the air, preventing the formation of deep compressive stress. At the same time, the high-energy laser directly burns the alloy surface, causing thermal damage and oxidation microcracks, which in turn become the inducing source of pitting corrosion.

[0058] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A preparation process for a corrosion-resistant nickel-based alloy, characterized in that, Includes the following steps: Electrolytic nickel plates, molybdenum bars, nickel-tantalum master alloys, ruthenium briquettes, nickel-tungsten master alloys, nickel-niobium master alloys, high-purity titanium wire, aluminum granules, and nickel-yttrium master alloys are subjected to vacuum induction melting and cast to obtain a casting body. Using fluoride slag, the casting body is subjected to ultrasonic-assisted electroslag treatment to obtain a remelted ingot. The remelted ingot is subjected to isothermal multi-directional forging and liquid nitrogen cooling to obtain a forged body. The forged body is subjected to solution treatment and two-stage aging treatment to obtain a semi-finished alloy. The semi-finished alloy is subjected to laser shock strengthening treatment to obtain the corrosion-resistant nickel-based alloy.

2. The preparation process of a corrosion-resistant nickel-based alloy according to claim 1, characterized in that, The specific process of the vacuum induction melting process is as follows: the crucible is tamped with alumina and the furnace is dried to remove moisture; the electrolytic nickel plate, the molybdenum bar, the nickel-tantalum master alloy, the ruthenium briquettes and the nickel-tungsten master alloy are placed in the crucible, and after vacuuming, the bottom material is completely melted, the nickel-niobium master alloy is added, and the temperature is controlled at 1540℃-1570℃. The temperature was then raised to 1580℃ and held at that temperature. Simultaneously, an electromagnetic stirrer was turned on, and a pulsed alternating magnetic field was applied. High-purity argon gas was introduced before tapping the steel. Then, the high-purity titanium wire, the aluminum granules, and the nickel-yttrium master alloy were added and stirred evenly to obtain a molten alloy. The alloy was then cast at 1480℃-1500℃ to obtain the casting. The content of each metal element in the molten alloy was as follows: Mo: 20%-22%, Ta: 6%-8%, W: 3%-4%, Nb: 1-3%, Ti: 1-2%, Al: 0.5-1.5%, Ru: 0.5%-1%, Y: 0.05%-0.1%, with the balance being Ni.

3. The preparation process of a corrosion-resistant nickel-based alloy according to claim 1, characterized in that, The specific process of the ultrasonic-assisted electroslag remelting treatment is as follows: using the fluoride slag material: 70% CaF2 + 20% Al2O3 + 10% CaO; the slag material needs to be roasted and dehydrated at 780℃-820℃ before remelting; using AC power, controlling the melting rate at 4-5 kg / min, ultrasonic waves are applied to the bottom pad of the water-cooled copper crystallizer to obtain the remelted ingot.

4. The preparation process of a corrosion-resistant nickel-based alloy according to claim 1, characterized in that, The specific process of isothermal multi-directional forging and liquid nitrogen cooling is as follows: after the remelted ingot is surface-finished, it is heated to 1160℃-1180℃, held at the temperature, and then subjected to three-dimensional multi-directional upsetting and drawing. After final forging, it is quenched in water to room temperature, wiped dry, and then immersed in a liquid nitrogen tank. After holding at the temperature, the forged body is obtained.

5. The preparation process of a corrosion-resistant nickel-based alloy according to claim 1, characterized in that, The specific process of the solution treatment and two-stage aging treatment is as follows: the forging body is heated to 1080℃-1120℃ and held for 2 hours; then the first-stage aging treatment is performed: the temperature is raised to 720℃ and held for 7-9 hours. After the holding is completed, it is cooled to the second aging temperature at a cooling rate of 50℃ / h. The second-stage aging treatment is performed: the temperature is lowered to 600℃-640℃ and held for 8 hours. Then it is directly removed from the furnace and air-cooled to room temperature to obtain the semi-finished alloy.

6. The preparation process of a corrosion-resistant nickel-based alloy according to claim 1, characterized in that, The specific process of the laser shock strengthening treatment is as follows: black tape is attached to the surface of the semi-finished alloy and covered with flowing pure water; a grid-like scanning is performed using an Nd:YAG nanosecond pulse laser to induce a stress layer on the surface, thereby obtaining the corrosion-resistant nickel-based alloy.

7. A corrosion-resistant nickel-based alloy, characterized in that, The raw materials for synthesizing the corrosion-resistant nickel-based alloy include electrolytic nickel plates, molybdenum bars, nickel-tantalum master alloys, ruthenium briquettes, nickel-tungsten master alloys, nickel-niobium master alloys, high-purity titanium wires, aluminum granules, and nickel-yttrium master alloys; the corrosion-resistant nickel-based alloy is prepared by the preparation method described in any one of claims 1-6.

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