Plasma cladding surfacing high-performance cladding layer on surface of 35CrMo medium carbon alloy steel and preparation method of plasma cladding surfacing high-performance cladding layer

Abstract

The invention provides a high-performance cladding layer for plasma cladding surfacing on the surface of 35CrMo medium-carbon alloy steel and a preparation method of the high-performance cladding layer, and belongs to the technical field of metal surface strengthening. The cladding layer is formed by plasma cladding surfacing of mixed metal powder, and the mixed metal powder is composed of (65% Ni60 + 35% WC) mixed powder and Fe90 powder. According to the method, the proportion of cladding materials is optimized, metallurgical bonding of the cladding layer and the 35CrMo alloy steel is achieved through the plasma cladding technology, the microhardness of the obtained cladding layer can reach 512.21 HV-613.2 HV and is improved by 1.71-2.04 times compared with the microhardness of matrix 35CrMo, the abrasion resistance is improved by 10.42 times or above compared with the abrasion resistance of 35CrMo, and good toughness and bonding strength are achieved; and the wear-resistant use requirements of heavy-duty gear shafts, gear teeth and other components can be effectively met. Meanwhile, the preparation method is stable in process, high in operability and suitable for industrial application.

Description

Technical Field

[0001] This invention relates to the field of metal surface strengthening technology, and in particular to a high-performance cladding layer for plasma cladding welding on the surface of 35CrMo medium carbon alloy steel and its preparation method. Background Technology

[0002] 35CrMo medium-carbon alloy steel is a commonly used alloy structural steel with high strength, toughness, and wear resistance. It is widely used in the manufacture of heavy-duty gear shafts, gear teeth, drive shafts, and other mechanical components. However, under harsh working conditions involving heavy loads, high speeds, or dust particles, the surfaces of these components are prone to wear, abrasive wear, and fretting wear, leading to a shortened service life and affecting the normal operation of the equipment.

[0003] To improve the surface properties of 35CrMo alloy steel components, existing technologies commonly employ surface strengthening methods such as spraying, electroplating, laser cladding, or conventional welding. Among these, spraying and electroplating result in a mechanical bond between the coating and the substrate, leading to low bonding strength and a tendency to peel off. While laser cladding can produce high-quality cladding layers, its high equipment cost and low processing efficiency make it unsuitable for large-scale industrial production. Conventional welding results in a high dilution rate of the cladding layer, poor uniformity, and a tendency to cause significant substrate deformation.

[0004] Plasma cladding welding technology, as an advanced surface strengthening technique, boasts advantages such as concentrated energy density, low dilution rate of the cladding layer, and metallurgical bonding with the substrate, and has been gradually applied in the field of metal surface strengthening. However, current plasma cladding welding technology for 35CrMo alloy steel suffers from problems such as unreasonable cladding material ratios, difficulty in achieving a balance between hardness and toughness of the cladding layer, and limited improvement in wear resistance. Therefore, developing a plasma cladding welding cladding layer that is suitable for 35CrMo alloy steel, has excellent performance, and a stable preparation process has significant practical application value. Summary of the Invention

[0005] The purpose of this invention is to provide a high-performance cladding layer for plasma cladding welding on the surface of 35CrMo medium carbon alloy steel and its preparation method, so as to solve the above-mentioned technical problems.

[0006] To achieve the above-mentioned objectives, the present invention provides the following technical solution: This invention provides a high-performance cladding layer for plasma cladding on the surface of 35CrMo medium carbon alloy steel. The high-performance cladding layer is formed by plasma cladding of mixed metal powder, which includes a mixed powder of 65%Ni60+35%WC and Fe90 powder. Based on the total mass of the mixed metal powder as 100%, the mass percentage of the mixed powder of 65%Ni60+35%WC is 40~60%, and the mass percentage of Fe90 powder is 40~60%.

[0007] Furthermore, the mass percentage of the 65%Ni60+35%WC mixed powder is 40%, and the mass percentage of the Fe90 powder is 60%.

[0008] Furthermore, the mass percentage of the 65%Ni60+35%WC mixed powder is 50%, and the mass percentage of Fe90 powder is 50%.

[0009] Furthermore, the mass percentage of the 65%Ni60+35%WC mixed powder is 60%, and the mass percentage of Fe90 powder is 40%.

[0010] Furthermore, the Ni60 is a nickel-based alloy powder, which serves as a matrix phase to provide support and resistance to plastic deformation; the WC is tungsten carbide powder with a microhardness of 1800-2400 HV, serving as a hard reinforcing phase; the Fe90 powder has good compatibility with the 35CrMo matrix and is used to optimize interfacial bonding and adjust the toughness of the cladding layer. The particle size of the Ni60 and WC is 50~150μm.

[0011] This invention also provides a method for preparing a high-performance cladding layer for plasma cladding welding on the surface of the above-mentioned 35CrMo alloy steel, comprising the following steps: 1) Substrate pretreatment: The 35CrMo substrate surface is sandblasted and degreased to remove surface oxide scale, oil and impurities, and then dried for later use; 2) Preparation of mixed powder: Weigh Ni60 powder, WC powder and Fe90 powder according to the ratio, put them into the mixing equipment for mixing, and obtain uniform mixed metal powder; 3) Plasma cladding welding: Plasma cladding equipment is used to melt the mixed metal powder under the action of the plasma arc heat source and deposit it onto the surface of 35CrMo to form a cladding layer.

[0012] Furthermore, the process parameters for plasma cladding welding are as follows: plasma arc current 80~120A, arc voltage 12~18V, ion gas flow rate 2~4L / min, shielding gas flow rate 8~12L / min, cladding speed 3~5mm / s, and decoking amount 3~8mm.

[0013] Furthermore, in step 2), the mixing time is 20-30 hours.

[0014] The beneficial effects of this invention are: 1. The cladding layer of this invention achieves a good match between surface microhardness and toughness by optimizing the ratio of (65% Ni60 + 35% WC) mixed powder and Fe90 powder. Specifically, the WC hard phase provides high wear resistance, the Ni60 matrix phase ensures overall support, and the Fe90 optimizes interfacial bonding and adjusts toughness. The resulting cladding layer has a microhardness of 512.21 HV-613.2 HV, which is 1.71-2.04 times higher than that of the 35CrMo matrix (300 HV), and its wear resistance is more than 10.42 times higher than that of 35CrMo medium carbon alloy steel, effectively resisting wear under harsh working conditions.

[0015] 2. The cladding layer of the present invention is metallurgically bonded to the 35CrMo substrate, and the bonding strength is much higher than that of traditional spraying and electroplating technologies, thus avoiding the problem of coating peeling off. At the same time, the addition of Fe90 powder alleviates the brittleness of the hard phase, reduces the risk of cracking of the cladding layer, and improves the overall reliability of the cladding layer.

[0016] 3. The preparation method of the present invention is stable, highly operable, and has clear mixing and cladding parameters, making it suitable for industrial mass production; the raw materials used are readily available and the cost is controllable, giving it a wider range of application prospects compared to laser cladding technology.

[0017] 4. The cladding layer of the present invention is suitable for surface strengthening of 35CrMo alloy steel components such as heavy-duty gear shafts, gear teeth, and transmission shafts. It can significantly extend the service life of the components and reduce equipment maintenance costs, and has important economic value and practical significance. Attached Figure Description

[0018] Figure 1 These are electron microscope images of the cladding layer obtained in Example 1 of the present invention at different angles and magnifications; Figure 2 These are electron microscope images of the cladding layer obtained in Example 2 of the present invention at different angles and magnifications; Figure 3 These are electron microscope images of the cladding layer obtained in Example 3 of the present invention at different angles and magnifications; Figure 4 This is the energy spectrum of the cladding layer obtained in Example 1 of the present invention; Figure 5 The energy spectrum of the cladding layer obtained in Example 2 of this invention; Figure 6 This is the energy spectrum of the cladding layer obtained in Example 3 of the present invention. Detailed Implementation

[0019] This invention provides a high-performance cladding layer for plasma cladding on the surface of 35CrMo medium carbon alloy steel. The high-performance cladding layer is formed by plasma cladding of mixed metal powder, which includes a mixed powder of 65%Ni60+35%WC and Fe90 powder. Based on the total mass of the mixed metal powder as 100%, the mass percentage of the mixed powder of 65%Ni60+35%WC is 40~60%, and the mass percentage of Fe90 powder is 40~60%.

[0020] In this invention, the mass percentage of the 65%Ni60+35%WC mixed powder is 40%, and the mass percentage of the Fe90 powder is 60%.

[0021] In this invention, the mass percentage of the 65%Ni60+35%WC mixed powder is 50%, and the mass percentage of the Fe90 powder is 50%.

[0022] In this invention, the mass percentage of the 65%Ni60+35%WC mixed powder is 60%, and the mass percentage of the Fe90 powder is 40%.

[0023] In this invention, Ni60 is a nickel-based alloy powder, which serves as a matrix phase to provide support and resistance to plastic deformation; WC is tungsten carbide powder with a hardness of 1800-2400 HV, which serves as a hard reinforcing phase; Fe90 powder has good compatibility with the 35CrMo matrix and is used to optimize interfacial bonding and adjust the toughness of the cladding layer. The particle size of Ni60 and WC is 50~150μm, preferably 80~120μm.

[0024] In this invention, Ni60 (nickel-based alloy) is used as the main cladding metal material, possessing good wear resistance, anti-galling properties, and a certain degree of toughness. It encapsulates and firmly bonds with the WC particles, providing overall support and resistance to plastic deformation.

[0025] Enhanced fatigue resistance: The plasma cladding layer is metallurgically bonded to the substrate (gear shaft), and its bonding strength is far higher than that of traditional surface treatment technologies such as spraying and electroplating.

[0026] Tungsten carbide (WC) is the most critical hard reinforcing phase. WC particles have extremely high hardness (1800-2400 HV) and are uniformly distributed in the cladding layer, which can effectively resist wear, abrasive wear and fretting wear during gear meshing, especially in harsh working environments with heavy loads, high speeds or dust / particulate matter.

[0027] The effect of Fe: Fe has good compatibility with the matrix, which can optimize the interface and promote metallurgical bonding (the interface strength is improved).

[0028] This invention also provides a method for preparing the high-performance cladding layer of the above-mentioned 35CrMo surface plasma cladding overlay, comprising the following steps: 1) Substrate pretreatment: The 35CrMo surface is sandblasted and degreased to remove surface oxide scale, oil and impurities, and then dried for later use; 2) Preparation of mixed powder: Weigh Ni60 powder, WC powder and Fe90 powder according to the ratio, put them into the mixing equipment for mixing, and obtain uniform mixed metal powder; 3) Plasma cladding welding: Plasma cladding equipment is used to melt the mixed metal powder under the action of the plasma arc heat source and deposit it onto the surface of 35CrMo to form a cladding layer.

[0029] In this invention, the process parameters for plasma cladding welding are: plasma arc current 80~120A, arc voltage 12~18V, ion gas flow rate 2~4L / min, shielding gas flow rate 8~12L / min, cladding speed 3~5mm / s, and decoking amount 3~8mm; preferably, the process parameters for plasma cladding welding are: plasma arc current 90~110A, arc voltage 14~16V, ion gas flow rate 2~3L / min, shielding gas flow rate 9~11L / min, cladding speed 4~5mm / s, and decoking amount 3~6mm.

[0030] In this invention, the mixing time in step 2) is 20-30 hours, preferably 24-26 hours.

[0031] The technical solutions provided by the present invention will be described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0032] Example 1

[0033] A high-performance cladding layer for plasma cladding welding on the surface of 35CrMo alloy steel, the mixed metal powder composition is 40% (65%Ni60+35%WC)+60%Fe90 (mass percentage).

[0034] The preparation method includes the following steps: (1) Pretreatment of the substrate surface: Select 35CrMo alloy steel specimen as the substrate, and perform sandblasting and degreasing treatment on its surface to remove oxide scale and impurities; then put it into anhydrous ethanol for ultrasonic degreasing treatment for 15 min, take it out and dry it at 80℃ for 2 h for later use; (2) Preparation of mixed powder: Weigh 80g (65%Ni60+35%WC) mixed powder and 120g Fe90 powder (total mass 200g), put them into a mixing tank, add bearing steel GCr15 steel balls (diameter 12.6mm: diameter 6mm=1:2) at a ball-to-material ratio of 1:1, control the rotation speed at 30r / min, mix for 24h at dry room temperature to obtain uniform mixed metal powder; (3) Plasma cladding welding: Plasma cladding equipment is used, with side powder feeding at a speed of 20g / min; the cladding process parameters are: plasma arc current 80A, arc voltage 12V, ion gas flow rate 2L / min, shielding gas flow rate 8L / min, cladding speed 3mm / s, and decoking amount 3mm; the cladding layer is formed by melting and deposition. (4) Post-treatment: The workpiece and cladding layer can be naturally cooled to room temperature after cladding.

[0035] The resulting cladding layer, after testing, exhibited a microhardness of 613.2 HV and a total wear amount of 0.0130 g, representing a 10.24-fold improvement in wear resistance compared to the 0.1355 g wear amount of the 35CrMo substrate surface. Its bonding strength was 485±15 MPa, and its impact toughness was 18.6±1.2 J / cm². 2 The cladding layer is tightly bonded to the substrate, with no cracking or peeling.

[0036] Example 2

[0037] A high-performance cladding layer for plasma cladding overlay on 35CrMo surface, the mixed metal powder composition is 50% (65% Ni60 + 35% WC) + 50% Fe90 (mass percentage).

[0038] The preparation method includes the following steps: (1) Pretreatment of the matrix: Select 35CrMo steel specimen as the matrix, and perform sandblasting and degreasing on its surface to remove oxide scale and impurities; then put it into anhydrous ethanol for ultrasonic degreasing treatment for 18 min, take it out and dry it at 90℃ for 2.5 h for later use; (2) Preparation of mixed powder: Weigh 100g of mixed powder (65%Ni60+35%WC) and 100g of Fe90 powder (total mass 200g), put them into a mixing tank, add bearing steel GCr15 steel balls (diameter 12.6mm: diameter 6mm=1:2) at a ball-to-material ratio of 1:1, control the rotation speed at 40r / min, mix at room temperature for 24h to obtain uniform mixed metal powder; (3) Plasma cladding welding: Plasma cladding equipment is used, with side powder feeding at a speed of 30g / min; the cladding process parameters are: plasma arc current 100A, arc voltage 15V, ion gas flow rate 3L / min, shielding gas flow rate 10L / min, cladding speed 4mm / s, and decoking amount 5mm; the cladding layer is formed by melting and deposition. (4) Post-treatment: The workpiece and cladding layer can be naturally cooled to room temperature after cladding.

[0039] The resulting cladding layer, after testing, exhibited a microhardness of 541.7 HV and a total wear amount of 0.0174 g, representing a 7.9-fold improvement in wear resistance compared to the 35CrMo alloy steel substrate. Its bonding strength was 472±13 MPa, and its impact toughness was 17.3±1.0 J / cm². 2 The cladding layer has a uniform structure, good toughness, and no obvious defects.

[0040] Example 3

[0041] A high-performance cladding layer for plasma cladding overlay on 35CrMo surface, the mixed metal powder composition is 60% (65% Ni60 + 35% WC) + 40% Fe90 (mass percentage).

[0042] The preparation method includes the following steps: (1) Pretreatment of the substrate: Select 35CrMo alloy steel specimens as the substrate, and perform sandblasting and degreasing treatment on the surface to remove oxide scale and impurities; then put them into anhydrous ethanol for ultrasonic degreasing treatment for 20 min, take them out and dry them at 100℃ for 3 h for later use; (2) Preparation of mixed powder: Weigh 120g (65%Ni60+35%WC) mixed powder and 80g Fe90 powder (total mass 200g), put them into a mixing tank, add bearing steel GCr15 steel balls (diameter 12.6mm: diameter 6mm=1:2) at a ball-to-material ratio of 1:1, control the rotation speed at 50r / min, mix at room temperature for 24h to obtain uniform mixed metal powder; (3) Plasma cladding welding: Plasma cladding equipment is used, with side powder feeding at a speed of 40g / min; the cladding process parameters are: plasma arc current 120A, arc voltage 18V, ion gas flow rate 4L / min, shielding gas flow rate 12L / min, cladding speed 5mm / s, and decoking amount 8mm; the cladding layer is formed by melting and deposition. (4) Post-treatment: The workpiece and cladding layer can be naturally cooled to room temperature after cladding.

[0043] The resulting cladding layer, after testing, exhibited a microhardness of 512.21 HV and a total wear amount of 0.0192 g, representing a 7.1-fold improvement in wear resistance compared to the 35CrMo alloy steel substrate. Its bonding strength was 458±14 MPa, and its impact toughness was 15.8±0.9 J / cm². 2 The cladding layer has a good metallurgical bond with the substrate, and its wear resistance meets the requirements for use.

[0044] Microhardness: The HVS microhardness tester was used to measure the microhardness of the sides of the polished, etched, and ground specimens. A load of 0.2 kg was applied for 10 seconds. The diagonal lengths D1 and D2 of the rhomboid indentation, measured through the eyepiece, were directly input into the control system, and the microhardness was then displayed on the LCD screen, avoiding the tedious table lookup and calculation process. Ten hardness values ​​were measured on each specimen cross-section, and the average value was taken.

[0045] Total wear: The wear of the specimen and cladding surface was measured using an M-200 wear testing machine in this test.

[0046] Test conditions: lubrication (10# machine oil), load F=10N, low speed 200rad / min.

[0047] The wear time was T=100min, and the wear was repeated 5 times (20min / time). After each wear, the specimen was ultrasonically cleaned, dried, and weighed.

[0048] The strength test standard is GB / T 16924-2019 (tensile shear test).

[0049] Impact toughness test standard: GB / T 229-2020 (Charpy V-notch).

[0050] Figure 1 , Figure 2 , Figure 3 The images show electron microscope (EM) images of the cladding layers obtained in Examples 1, 2, and 3, respectively. As can be seen from the images, the WC particles exhibit coarse hexagonal crystals with blunted edges, and some particles are cracked. Fe90 forms a dark gray α-Fe phase as the matrix phase, creating a continuous network.

[0051] γ-Ni isolated islands: Regarding the precipitated phase, F C is distributed along the WC interface, C Pinning ferrite grain boundaries. At the WC / Fe interface, a reaction layer forms F. C transition phase; matrix details are as follows: ferrite grains contain high-density dislocations; in the pearlite domain, C-rich regions in Fe90 form layered pearlite (α-Fe+F). C). Ni60 residues appear as γ-Ni islands surrounded by α-Fe, with NiF present at the interface. Intermetallic compounds.

[0052] The structural feature is that F is generated in the reaction layer at the WC / Fe interface. C transition phase; the matrix details are ferrite grains with high-density dislocations, and layered pearlite (α-Fe+F) formed by the C-rich regions of Fe90 in the pearlite domains. C). The Ni60 residue still consists of γ-Ni islands surrounded by α-Fe, with NiF present at the interface. Intermetallic compounds. Furthermore, ferrite defects manifest as dislocation network entanglements that bypass F. C particles also exhibit stacking faults and vacancy clusters. The precipitated phase contains nano-carbide particles, such as C... (Face-centered cubic), F C (orthogonal structure).

[0053] Figure 4 , Figure 5 , Figure 6 The following table shows the energy spectrum diagrams of the cladding layer cross sections obtained in Examples 1, 2, and 3, respectively. The table below shows the proportion of each element in the end face tested at different sites in the energy spectrum diagrams.

[0054] Table 1 Figure 4 The proportion of each element in the 89 points

[0055] Analysis: The high proportion of Ni60 and Fe elements in this group indicates good surface metal cladding properties.

[0056] Table 2 Figure 5 The proportion of each element in the 96 points

[0057] Table 3 Figure 6 The proportion of each element in 102 points

[0058] Analysis: The high Fe content is due to the melting of the 35CrMo alloy steel base during the cladding process; the high Ni content is due to the large proportion of Ni60 in the cladding material; the high W and C content is because the WC did not melt and the EDS points were applied to large WC particles. Simultaneously, the high O content indicates material oxidation.

[0059] The composition of the cladding layer of Comparative Examples 1 to 4 is shown in Table 4.

[0060] Table 4 Performance test data of the cladding layers obtained in Comparative Examples 1-4

[0061] The test data above shows that: Comparative Example 1 (without Fe90): has the highest microhardness (≈729HV), but its impact toughness and bonding strength are extremely low, proving the key role of Fe90 in optimizing the interface and improving wear resistance stability. Comparative Example 2 (Fe exceeding the upper limit): It has the best toughness, but the hardness is only 445HV (27% lower than Example 1), and the wear is 1.8 times that of Example 1, which proves that the proportion of Fe90 exceeding 60% will lead to a weakening of the hard phase effect and a significant deterioration of wear resistance. Comparative Example 3 (HVOF spraying): The hardness is close to that of Example 1, but the wear is 2.4 times that of Example 1. The bonding strength and toughness are extremely poor, which proves the wear resistance and reliability advantages of plasma cladding metallurgical bonding compared with mechanical bonding. Comparative Example 4 (hard chrome plating): It had the highest hardness, but the wear was 3.25 times that of Example 1, and the toughness and bonding strength were the worst.

[0062] Compared with conventional cladding (Comparative Example 1): This invention (Examples 1-3) improves wear resistance by 1.9 to 3.3 times, bonding strength by 43 to 48%, and impact toughness by 61 to 69% with slightly lower hardness, proving that the addition of Fe90 produces an unexpected synergistic optimization effect; Compared with boundary ratio (Comparative Example 2): This invention improves hardness by 15 to 38% and wear resistance by 43 to 77% with slightly decreased toughness, proving that "Fe90 content of 40 to 60%" is the optimal range for achieving performance balance, rather than an arbitrary choice; Compared with traditional surface technologies (Comparative Examples 3-4): This invention improves wear resistance by 3.9 to 7.6 times, bonding strength by 2.1 to 3.8 times, and impact toughness by 1.9 to 3.0 times, solving the technical problems of "hard and brittle, not durable wear resistance, and weak bonding" in traditional technologies. This invention has comprehensive advantages in multiple dimensions of "hardness-wear resistance-toughness-bonding strength".

[0063] This invention uses 35CrMo alloy steel as the matrix and a 40% (65%Ni60+35%WC)+60%Fe90 cladding layer. The maximum microhardness of the cladding layer is 613.2 HV, which is 2.04 times that of the 35CrMo surface. Within the 35CrMo group, as the proportion of (65%Ni60+35%WC) mixture increases, the proportion of Fe90 decreases, and its microhardness decreases. In the wear measurement of the 35CrMo alloy coating on medium-carbon alloy steel, the total wear of 35CrMo was 0.1355g. The 40% (35%Ni60+65%WC)+60%Fe90 cladding layer exhibited the best wear resistance, which was 10.42 times that of the 35CrMo matrix.

[0064] 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 high-performance cladding layer for plasma cladding overlay on the surface of 35CrMo medium-carbon alloy steel, characterized in that, The high-performance cladding layer is formed by plasma cladding welding of mixed metal powder, which includes a mixture of 65% Ni60 + 35% WC powder and Fe90 powder. Based on the total mass of the mixed metal powder as 100%, the mass percentage of the mixed powder of 65%Ni60+35%WC is 40~60%, and the mass percentage of Fe90 powder is 40~60%.

2. The high-performance cladding layer of 35CrMo medium carbon alloy steel surface plasma cladding overlay as described in claim 1, characterized in that, The mass percentage of the 65%Ni60+35%WC mixed powder is 40%, and the mass percentage of Fe90 powder is 60%.

3. The high-performance cladding layer of 35CrMo medium carbon alloy steel surface plasma cladding overlay as described in claim 1, characterized in that, The mass percentage of the 65%Ni60+35%WC mixed powder is 50%, and the mass percentage of Fe90 powder is 50%.

4. The high-performance cladding layer of 35CrMo medium carbon alloy steel surface plasma cladding overlay as described in claim 1, characterized in that, The mass percentage of the 65%Ni60+35%WC mixed powder is 60%, and the mass percentage of Fe90 powder is 40%.

5. The high-performance cladding layer formed by plasma cladding on the surface of 35CrMo medium-carbon alloy steel according to any one of claims 1 to 4, characterized in that, The Ni60 is a nickel-based alloy powder, which serves as a matrix phase to provide support and resistance to plastic deformation; the WC is tungsten carbide powder with a hardness of 1800-2400 HV, which serves as a hard reinforcing phase; the Fe90 powder has good compatibility with the 35CrMo matrix and is used to optimize the interface bonding and adjust the toughness of the cladding layer. The particle size of the Ni60 and WC is 50~150μm.

6. The method for preparing a high-performance cladding layer by plasma cladding welding on the surface of 35CrMo medium-carbon alloy steel according to any one of claims 1 to 5, characterized in that, Includes the following steps: 1) Surface pretreatment of 35CrMo medium carbon alloy steel: The surface of 35CrMo is sandblasted and degreased to remove surface oxide scale, oil and impurities, and then dried for later use. 2) Preparation of mixed powder: Weigh Ni60 powder, WC powder and Fe90 powder according to the ratio, put them into the mixing equipment for mixing, and obtain uniform mixed metal powder; 3) Plasma cladding welding: Plasma cladding equipment is used to melt the mixed metal powder under the action of the plasma arc heat source and deposit it onto the surface of 35CrMo alloy steel to form a cladding layer.

7. The preparation method according to claim 6, characterized in that, The process parameters for plasma cladding welding are as follows: plasma arc current 80~120A, arc voltage 12~18V, ion gas flow rate 2~4L / min, shielding gas flow rate 8~12L / min, cladding speed 3~5mm / s, and decoking amount 3~8mm.

8. The preparation method according to claim 6 or 7, characterized in that, In step 2), the mixing time is 20-30 hours.

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