A high-wear-resistant and corrosion-resistant robot joint shaft based on powder steel and a manufacturing method thereof

Abstract

This invention discloses a high wear-resistant and corrosion-resistant robot joint shaft based on powder steel and its manufacturing method. The shaft is made of powder steel with the following chemical composition by mass percentage: C 1.2~1.4%, Si≤0.6%, Mn≤0.6%, Cr 11.5~14.5%, Mo 2.0~3.0%, V≥3.6%, W≤1.0%, Nb≥0.5%, and satisfying W+Mo+V+Nb≥6.7%, with the balance being Fe and unavoidable impurities. The diameter of the joint shaft is 15~50mm. The carbide inhomogeneity of the powder steel is rated as not exceeding level 1 according to GB / T14979-1994 standard. The surface roughness Ra of the joint shaft is ≤0.1μm, and the dimensional accuracy is controlled within ±2μm. Through the specific composition ratio of the powder steel material and the optimized manufacturing process, the wear resistance, corrosion resistance, dimensional stability, and service life of the robot joint shaft under high load and corrosive environments are effectively improved, balancing high performance and economy.

Description

Technical Field

[0001] This invention relates to the field of key robot components and high-performance material manufacturing technology, specifically to a high wear-resistant and corrosion-resistant robot joint shaft based on powder steel and its manufacturing method. Background Technology

[0002] Industrial robots are core equipment in modern high-end manufacturing, precision assembly, and logistics handling. Their joints, as key components for power transmission and motion bearing, are subjected to high-frequency periodic loads, contact stresses, and potential impact loads over long periods of time. The performance of robot joints, especially their wear resistance, corrosion resistance, and long-term dimensional stability, directly determines the robot's positioning accuracy, service life, and operational reliability. In complex working conditions such as collaborative robots, painting robots, cleanroom robots, and marine operation robots, joints also face harsh environmental challenges such as media corrosion and temperature and humidity changes.

[0003] With the rapid popularization of robots, especially in fields such as automobile assembly, heavy-duty handling, fire rescue, and special operations, increasingly stringent requirements are being placed on the load-bearing capacity, wear resistance, and corrosion resistance of robot joint axes. Traditional joint axes mostly use alloy steels such as GCr15 and 50CrMo4, which are relatively inexpensive, but their wear resistance, corrosion resistance, and service life are insufficient to meet actual needs in high-load and complex corrosive environments, restricting the reliability of robots and the expansion of their application scenarios. In addition, increasing the alloy content to improve performance can lead to the formation and uneven distribution of large-sized carbides, which not only exacerbates material brittleness but also makes it difficult to control retained austenite, seriously affecting the machining accuracy and dimensional stability of parts. Especially for precision joint axes, the machining cost is far higher than the material cost. If performance is improved solely by traditional processes, it is often accompanied by a significant increase in machining difficulty, leading to an increase in overall manufacturing costs.

[0004] Therefore, a high wear-resistant and corrosion-resistant robot joint shaft based on powder steel and its manufacturing method are proposed to solve the problems mentioned above. Summary of the Invention

[0005] The purpose of this invention is to provide a high wear-resistant and corrosion-resistant robot joint shaft based on powder steel and its manufacturing method, so as to solve the problems mentioned in the background art that the robot joint shafts made of traditional alloy steel are difficult to meet the requirements of high load and complex environment in terms of wear resistance, corrosion resistance and dimensional stability, and that performance improvement is often accompanied by increased processing difficulty and cost.

[0006] To achieve the above objectives, the present invention provides the following technical solution: a high wear-resistant and corrosion-resistant robot joint axis based on powder steel, which is made of powder steel. The chemical composition of the powder steel, by mass percentage, is: C 1.2~1.4%, Si≤0.6%, Mn≤0.6%, Cr 11.5~14.5%, Mo 2.0~3.0%, V≥3.6%, W≤1.0%, Nb≥0.5%, and satisfies W+Mo+V+Nb≥6.7%, with the balance being Fe and unavoidable impurities.

[0007] Preferably, the diameter of the joint axis is 15~50mm.

[0008] Preferably, the carbide inhomogeneity of the powder steel is rated as grade 1 according to GB / T14979-1994 standard.

[0009] Preferably, the surface roughness Ra of the joint shaft is ≤0.1μm, and the dimensional accuracy is controlled within ±2μm.

[0010] The present invention also provides a method for the aforementioned high wear-resistant and corrosion-resistant robot joint axis, comprising the following steps: S1. Powder metallurgy rod making: providing molten steel having the chemical composition of claim 1, performing gas atomization to produce powder, then performing hot isostatic pressing densification treatment on the powder, and then forging or rolling to form rods; S2. Rough machining: The bar stock is sawed and rough machined on a CNC lathe; S3. Heat treatment: Vacuum quenching, deep cryogenic treatment and multiple tempering are performed sequentially on the rough-machined workpiece. S4. Finishing: The heat-treated workpiece is sequentially subjected to CNC precision turning, external cylindrical grinding, internal cylindrical grinding and end face grinding to obtain the high wear-resistant and corrosion-resistant robot joint axis.

[0011] Preferably, in step S1, the molten steel is obtained by a process including induction furnace or electric arc furnace melting, LF furnace refining and VD furnace vacuum degassing.

[0012] Preferably, in step S1, before performing the gas atomization powdering, the heating temperature of the molten steel in the tundish is not lower than 1600°C; Preferably, in step S1, the pressure of the inert gas used for gas atomization powdering is not less than 16 bar; The billet after hot isostatic pressing is forged or rolled at 1170~1230℃ with a deformation ratio greater than 6:1.

[0013] Preferably, in step S1, after forging or rolling, the bar stock is further subjected to spheroidizing annealing at 780~850°C. The carbide inhomogeneity of the spheroidized annealed bar stock shall not exceed grade 1 according to the GB / T14979-1994 standard.

[0014] Preferably, in step S2, the roughing parameters are: spindle speed 400~700 r / min, feed rate 0.4~0.6 mm / r, and machining allowance of 0.3~0.4 mm in the diameter direction and 0.4~0.5 mm in the length direction; the cutting tool used is a carbide cutting tool with a hardness ≥88HRA.

[0015] Preferably, in step S3, the specific process of vacuum quenching is as follows: heating to 600~650℃ at a rate of ≤300℃ / h and holding for 1~2h, then heating to 850~950℃ and holding for 2~3h, then heating to 1080~1150℃ at a rate of ≤250℃ / h and holding for 0.5~2h, and after holding, cooling to 60~100℃ with inert gas at a pressure of 0.5~1.0MPa or quenching oil at a temperature of ≤80℃.

[0016] Preferably, in step S3, the cryogenic treatment is carried out at -140~-196℃ for 3~5 hours; the tempering is performed 2~3 times, each tempering is held at 520~620℃ for 4~6 hours and then air-cooled; or, the tempering is performed at 180~280℃ for no less than 3 low-temperature temperings.

[0017] Preferably, in step S4, the machining parameters of the CNC precision turning are: spindle speed 800~1300 r / min, feed rate 0.06~0.08 mm / r.

[0018] Preferably, in step S4, the external cylindrical grinding includes rough grinding and fine grinding using a cubic boron nitride grinding wheel; the grinding wheel grit size for rough grinding is 100~200 mesh, and the feed rate is 0.01~0.015 mm; the grinding wheel grit size for fine grinding is 500~600 mesh, and the feed rate is 0.001~0.005 mm; the axial movement speed for both rough grinding and fine grinding is 30~40 mm / s.

[0019] Preferably, in step S4, the internal grinding is fine grinding, with a feed rate of 0.001~0.005mm and an axial movement speed of 40~80mm / s.

[0020] Compared with the prior art, the beneficial effects of the present invention are as follows: This high wear-resistant and corrosion-resistant robot joint shaft based on powder steel and its manufacturing method effectively improve the wear resistance, corrosion resistance, dimensional stability and service life of the robot joint shaft under high load and corrosive environments through powder steel material with specific component ratios and optimized manufacturing processes, thus balancing high performance and economy. The specific details are as follows: First, the robot joint axis of this invention is made of powder steel with a specific chemical composition ratio, effectively solving the technical pain points of traditional alloy steel joint axes, such as insufficient wear resistance, corrosion resistance, and short service life under high loads and complex corrosive environments. It also avoids the problems of large-sized carbides and uneven carbide distribution that easily arise from simply increasing the alloy content. By precisely controlling the mass percentages of elements such as C, Cr, Mo, V, and Nb in the powder steel, and strictly meeting the requirement of W+Mo+V+Nb≥6.7%, combined with a carbide inhomogeneity rating of no more than level 1 according to GB / T14979-1994, the joint axis forms a dispersed and refined carbide structure, improving the material's hardness and wear resistance, while reducing the content of retained austenite, improving material brittleness, and ensuring that the joint axis maintains good structural stability under harsh working conditions such as automotive assembly and heavy-duty handling, effectively extending its service life.

[0021] Secondly, the manufacturing method of this invention, through the coordinated processes of powder metallurgy rod making, rough machining, targeted heat treatment, and finish machining, fully leverages the material advantages of powder steel with specific proportions while effectively ensuring the machining accuracy and performance of the joint shaft. In the powder metallurgy stage, gas atomization powder making, hot isostatic pressing densification, and forging / rolling processes, combined with subsequent spheroidizing annealing, further refine the carbide structure, laying the foundation for subsequent processing and performance improvement. The combined heat treatment process of vacuum quenching, deep cryogenic treatment, and multiple tempering effectively eliminates processing stress, further reduces the content of retained austenite, and improves the dimensional stability of the joint shaft. The finish machining processes of CNC precision turning, multi-pass grinding, and end face grinding control the surface roughness of the joint shaft to Ra≤0.1μm and the dimensional accuracy to within ±2μm. Combined with the material's inherent corrosion resistance, this effectively avoids the problem of decreased accuracy caused by corrosion and wear in complex environments. At the same time, reasonable process parameter settings reduce processing difficulty and avoid the problem of drastically increased manufacturing costs associated with improving performance using traditional processes, thus balancing product performance and production economy. Attached Figure Description

[0022] Figure 1 This is a microstructure diagram of the annealed structure in Example 1 of this invention; Figure 2 This is a microstructure diagram of the tissue after heat treatment in Example 1 of this invention; Figure 3 This is a graph showing the relationship between heat treatment and hardness in Example 1 of this invention; Figure 4 This is a microstructure diagram of the comparative example 1GCr15 steel after tempering in this invention. Detailed Implementation

[0023] 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.

[0024] This invention discloses a high wear-resistant and corrosion-resistant robot joint axis based on powder steel. Its core lies in the use of powder steel with a specific chemical composition ratio, and the optimization of the manufacturing process to achieve a balance between high performance and economy. The manufacturing method sequentially includes four core processes: powder metallurgy rod making, rough machining, heat treatment, and finish machining. The process parameters of each process are coordinated to fully utilize the material advantages of powder steel, ensuring the machining accuracy and performance of the joint axis. The technical solution of this invention is described in detail below through specific embodiments, while comparative examples are provided to verify the beneficial effects of this invention.

[0025] Example 1 This embodiment provides a high wear-resistant and corrosion-resistant robot joint axis based on powder steel. The chemical composition of the powder steel, by mass percentage, is: C 1.21%, Si 0.39%, Mn 0.41%, Cr 13.4%, Mo 2.3%, V 3.8%, Nb 1.8%, W 0.2%, with the balance being Fe and unavoidable impurity elements. Calculations show that the sum of the mass percentages of W+Mo+V+Nb in this powder steel is 8.1%, satisfying the requirement of W+Mo+V+Nb ≥ 6.7% in claim 1.

[0026] The manufacturing method of the high wear-resistant and corrosion-resistant robot joint axis described in this embodiment specifically includes the following steps: S1. Powder metallurgy rod making First, a combined process of induction furnace melting, LF furnace refining, and VD furnace vacuum degassing is used to refine the raw materials, resulting in refined molten steel with uniform composition and qualified purity. The refined molten steel is then poured into a tundish, and the heating temperature of the molten steel in the tundish is controlled at 1610℃ to ensure that the molten steel has good atomization fluidity. Subsequently, nitrogen gas at a pressure of 18 bar is used as an inert gas to atomize and pulverize the molten steel, obtaining uniformly sized powdered steel. The powdered steel is then subjected to hot isostatic pressing densification treatment to form round billets with a diameter of 500 mm.

[0027] The round billet is held at 1200℃ for more than 10 hours for homogenization treatment to eliminate compositional segregation and structural stress inside the billet. Then, the billet is forged and opened, and then the opened billet is heated at 1160℃ for 4 hours and rolled by a rolling mill to produce bars with a diameter of Φ15~30mm. The bars are placed in a resistance heating furnace and heated at 800℃ for spheroidizing annealing treatment. After annealing, the hardness of the bars is 202HB, and the eutectic carbide inhomogeneity and bulk carbide rating meet the Class 1 requirements of GB / T14979-1994 standard. Finally, the annealed bars are subjected to flaw detection, sawing and finishing to obtain qualified bars that meet the requirements of subsequent processing.

[0028] S2. Rough machining The qualified bar stock obtained in step S1 is rough-machined using a CNC lathe. A carbide tool with a hardness of 88HRA is selected, and the rough machining process parameters are controlled as follows: spindle speed is 500r / min, feed rate is 0.53mm / r, machining allowance in the diameter direction is 0.31mm, and machining allowance in the length direction is 0.40mm. Through the above rough machining, the excess material on the surface of the bar stock is removed, and it is initially formed into a blank for the robot joint axis.

[0029] S3. Heat Treatment The rough-machined blank obtained in step S2 is placed in a vacuum quenching furnace for vacuum quenching. The specific process is as follows: the temperature is raised to 600℃ at a heating rate of 250℃ / h and held for 1 hour to complete the preheating treatment; then the temperature is raised to 850℃ and held for 2 hours to perform austenitization and homogenization treatment; then the temperature is raised to 1120℃ at a heating rate of 200℃ / h and held for 0.5 hours to ensure that the carbides are fully dissolved; after the holding period, high-pressure nitrogen gas with a pressure of 0.8MPa is used as the cooling medium to cool the blank to 80℃ to complete the vacuum quenching process.

[0030] The vacuum-quenched blank was placed in a -160℃ cryogenic chamber for cryogenic treatment for 3 hours. After cryogenic treatment, the blank was removed and placed in the air to naturally warm up to room temperature. Subsequently, the blank was tempered three times. The specific process was as follows: the temperature was raised to 200℃ at a rate of 200℃ / h, held for 6 hours, and then air-cooled to room temperature. After tempering, the hardness of the blank was measured to be 61HRC, and the residual austenite content was effectively controlled.

[0031] S4. Finishing First, the heat-treated blank is precision-machined using a CNC lathe. The machining parameters are controlled as follows: spindle speed 900 r / min, feed rate 0.07 mm / r, and a carbide cutting tool with a hardness of 92 HRA is selected to ensure the surface quality of the precision machining. After precision machining, the outer diameter is ground using a 100-grit cubic boron nitride (CBN) grinding wheel with a grinding feed rate of 0.01 mm, machining the blank to a remaining machining allowance of 20~30 μm. Then, a 500-grit cubic boron nitride (CBN) grinding wheel is used for fine grinding with a grinding feed rate of 0.003 mm and an axial motion speed of 60 mm / s. At the same time, the inner diameter is finely ground, with the inner diameter fine grinding feed rate controlled at 0.003 mm and the axial motion speed at 60 mm / s. Finally, the blank is end-face ground using a double-end-face grinding machine to achieve the preset length dimension, resulting in the finished robot joint axis.

[0032] The performance of the finished robot joint axis prepared in this embodiment was tested, and the test results are as follows: the hardness after cryogenic treatment is 63 HRC, the hardness after tempering is 61 HRC, the retained austenite content is 1.8%, and the deformation after tempering is controlled within 0.1 μm / mm; the maximum size of the eutectic carbide is 3 μm, and the eutectic carbide inhomogeneity is rated as level 1 according to GB / T14979-1994 standard; the surface roughness Ra of the joint axis is ≤0.1 μm, and the dimensional accuracy is controlled within ±2 μm (1 μm in this embodiment).

[0033] The joint shaft prepared in this embodiment was compared with the GCr15 steel joint shaft commonly used in the prior art. Under the same working conditions and the same test time, the wear of the joint shaft in this embodiment was only 1 / 15 to 1 / 10 of that of the GCr15 steel joint shaft. After a 24-hour salt spray test, the corrosion resistance of the joint shaft in this embodiment was more than 20 times that of the GCr15 steel joint shaft, which fully demonstrates the technical advantages of the present invention.

[0034] Example 2 This embodiment provides a high wear-resistant and corrosion-resistant robot joint axis based on powder steel. The chemical composition of the powder steel, by mass percentage, is: C 1.28%, Si 0.37%, Mn 0.40%, Cr 12.4%, Mo 2.4%, V 4.1%, Nb 1.7%, W 0.4%, with the balance being Fe and unavoidable impurity elements. Calculations show that the sum of the mass percentages of W+Mo+V+Nb in this powder steel is 8.6%, satisfying the requirement of W+Mo+V+Nb ≥ 6.7% in claim 1.

[0035] The manufacturing method of the high wear-resistant and corrosion-resistant robot joint axis described in this embodiment specifically includes the following steps: S1. Powder metallurgy rod making The same refining process as in Example 1 was used, namely induction furnace melting, LF furnace refining and VD furnace vacuum degassing, to obtain refined molten steel. The refined molten steel was poured into a tundish and the temperature of the molten steel in the tundish was controlled at 1600°C. Nitrogen gas at a pressure of 22 bar was used as an inert gas to atomize the molten steel into powder. The resulting powder was subjected to hot isostatic pressing densification treatment to form a round billet with a diameter of 500 mm.

[0036] The round billet is held at 1190℃ for more than 10 hours for homogenization treatment; then it is forged and opened, and then the opened billet is heated at 1160℃ for 4 hours and rolled into bars with a diameter of 15~30mm by a rolling mill; the bars are placed in a resistance heating furnace and the heating temperature is controlled at 820℃ for spheroidizing annealing treatment. After annealing, the hardness of the bars is 211HB, and the eutectic carbide inhomogeneity and bulk carbide rating meet the Class 1 requirements of GB / T14979-1994 standard; after flaw detection, sawing and finishing, qualified bars are obtained.

[0037] S2. Rough machining Rough machining was performed using a CNC lathe with a carbide tool of 88HRA hardness. The machining parameters were controlled as follows: spindle speed of 500r / min, feed rate of 0.5mm / r, machining allowance in the diameter direction of 0.3mm, and machining allowance in the length direction of 0.40mm. After machining, a robot joint shaft blank was obtained.

[0038] S3. Heat Treatment The rough-machined blank is placed in a vacuum quenching furnace for vacuum quenching. The specific process is as follows: the temperature is raised to 600℃ at a heating rate of 250℃ / h and held for 1 hour; the temperature is then raised to 850℃ and held for 2 hours; the temperature is then raised to 1150℃ at a heating rate of 200℃ / h and held for 0.5 hours; after the holding period, quenching oil at 50℃ is used as the cooling medium to cool the blank to 60℃, thus completing the vacuum quenching.

[0039] The vacuum-quenched blank was placed in a -180℃ cryogenic chamber for 3 hours. After cryogenic treatment, it was removed and allowed to naturally warm to room temperature in the air. Then, it was tempered three times. The specific process was as follows: the temperature was raised to 550~570℃ at a heating rate of 200℃ / h, held for 3 hours, and then air-cooled to room temperature. After tempering, the hardness of the blank was measured to be 62HRC.

[0040] S4. Finishing CNC precision turning was performed on a CNC lathe with a spindle speed of 800 r / min and a feed rate of 0.06 mm / r, using a carbide cutting tool with a hardness of 93 HRA. After precision turning, external cylindrical grinding was performed using a 150-grit cubic boron nitride (CBN) grinding wheel for rough grinding with a feed rate of 0.012 mm, until the remaining machining allowance was 10~20 μm. Subsequently, fine grinding was performed using a 600-grit cubic boron nitride (CBN) grinding wheel with a feed rate of 0.002 mm and an axial motion speed of 40 mm / s. At the same time, internal cylindrical fine grinding was performed, with the feed rate controlled at 0.002 mm and the axial motion speed at 40 mm / s. Finally, the joint shaft was machined to the preset length using a double-end face grinder to obtain the finished joint shaft.

[0041] The performance of the finished robot joint axis prepared in this embodiment was tested, and the test results are as follows: the hardness after cryogenic treatment is 64 HRC, the hardness after tempering is 62 HRC, the retained austenite content is 1.1%, and the deformation after tempering is controlled within 0.1 μm / mm; the maximum size of the eutectic carbide is 2 μm, and the eutectic carbide inhomogeneity is rated as level 1 according to GB / T14979-1994 standard; the surface roughness Ra≤0.1 μm, and the dimensional accuracy is -1 μm (meeting the requirement of ±2 μm).

[0042] Performance comparison tests show that, under the same working conditions and test time, the wear of the joint shaft in this embodiment is only 1 / 20 of that of the GCr15 steel joint shaft; after a 24-hour salt spray test, the corrosion resistance of the joint shaft in this embodiment is more than 10 times that of the GCr15 steel joint shaft, further verifying the technical effect of the present invention.

[0043] Comparative Example 1 This comparative example uses GCr15 steel, commonly used in the prior art, as the raw material to prepare robot joint axes for performance comparison with the product of Example 2 of this invention. The specific preparation process is as follows: Commercially available qualified GCr15 steel was selected, and the same roughing and finishing processes as steps S2 and S4 in Example 2 were used to process and shape the GCr15 steel; the heat treatment process adopted was conventional quenching and tempering, as follows: (1) Quenching: Place the GCr15 steel billet into a vacuum furnace and heat it to 600℃ at a heating rate of 250℃ / h, and hold it for 1h; then heat it to 850℃ and hold it for 1h; after holding, cool it to 60~80℃ with quenching oil at 50℃, and take it out of the furnace to complete the quenching. (2) Deep cryogenic treatment: The quenched billet is placed in a deep cryogenic chamber at -180℃ for 3 hours. After treatment, it is placed in the air to naturally warm up to room temperature. (3) Tempering: The deep-cooled billet is placed in a box furnace and heated to 160~180℃ at a heating rate of 200℃ / h. After holding at the temperature for a certain time, it is taken out of the furnace and air-cooled. The tempering is repeated 3 times in total, and the hardness of the product is finally controlled at 60~62HRC.

[0044] The performance of the GCr15 steel joint shaft prepared in this comparative example was tested, and the results are as follows: the maximum size of the eutectic carbide is 4 μm, the eutectic carbide inhomogeneity is rated as level 3 according to GB / T14979-1994 standard; the quenching hardness is 62 HRC, and the hardness after tempering is 60 HRC; the retained austenite content is 1.8%; the deformation of the product after tempering is about 1 μm / mm; the machining accuracy is 2 μm; the surface roughness and other dimensional parameters are basically the same as those in Example 2.

[0045] Comparative Example 2 This comparative example also uses commercially available qualified GCr15 steel and adopts the same heat treatment process as Comparative Example 1. The roughing and finishing processes are outsourced to an external manufacturer (not the processing process disclosed in this invention). The robot joint axis is finally prepared to compare the impact of the processing process on the product performance.

[0046] The performance of the joint shaft prepared in this comparative example was tested, and the test results are as follows: the maximum size of the eutectic carbide is 4 μm, the eutectic carbide inhomogeneity is level 3; the quenching hardness is 62 HRC, and the hardness after tempering is 60 HRC; the retained austenite content is 1.8%; the machining accuracy is ±5 μm; the wear amount and corrosion resistance are similar to those of comparative example 1, and are far lower than those of the product of example 2 of this invention.

[0047] Performance comparison between the examples and the comparative examples The robot joint axes prepared in Example 2, Comparative Example 1, and Comparative Example 2 were subjected to comprehensive performance testing. The test results are summarized in Table 1, as follows: ; Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A high wear-resistant and corrosion-resistant robot joint axis based on powder steel, characterized in that, Made of powder steel, the chemical composition of which, by mass percentage, is: C 1.2~1.4%, Si≤0.6%, Mn≤0.6%, Cr 11.5~14.5%, Mo 2.0~3.0%, V≥3.6%, W≤1.0%, Nb≥0.5%, and satisfies W+Mo+V+Nb≥6.7%, with the balance being Fe and unavoidable impurities.

2. The high wear-resistant and corrosion-resistant robot joint axis based on powder steel according to claim 1, characterized in that: The diameter of the joint axis is 15~50mm.

3. The high wear-resistant and corrosion-resistant robot joint axis based on powder steel according to claim 1, characterized in that: The carbide inhomogeneity of the powder steel shall not exceed level 1 according to the GB / T14979-1994 standard.

4. The high wear-resistant and corrosion-resistant robot joint axis based on powder steel according to claim 1, characterized in that: The surface roughness Ra of the joint shaft is ≤0.1μm, and the dimensional accuracy is controlled within ±2μm.

5. A method for manufacturing a highly wear-resistant and corrosion-resistant robot joint shaft as described in any one of claims 1-4, characterized in that, Includes the following steps: S1. Powder metallurgy rod making: providing molten steel with the chemical composition of claim 1, performing gas atomization to produce powder, then performing hot isostatic pressing densification treatment on the powder, and then forging or rolling to form rods; S2. Rough machining: The bar stock is sawed and rough machined on a CNC lathe; S3. Heat treatment: Vacuum quenching, deep cryogenic treatment and multiple tempering are performed sequentially on the rough-machined workpiece. S4. Finishing: The heat-treated workpiece is sequentially subjected to CNC precision turning, external cylindrical grinding, internal cylindrical grinding and end face grinding to obtain the high wear-resistant and corrosion-resistant robot joint axis.

6. The method according to claim 5, characterized in that, In step S1, the molten steel is obtained by refining through a process including induction furnace or electric arc furnace melting, LF furnace refining and VD furnace vacuum degassing.

7. The method according to claim 6, characterized in that, In step S1, before the gas atomization powdering is performed, the heating temperature of the molten steel in the tundish is not lower than 1600°C.

8. The method according to claim 5, characterized in that, In step S1, the pressure of the inert gas used for gas atomization powder production is not less than 16 bar; The billet after hot isostatic pressing is forged or rolled at 1170~1230℃ with a deformation ratio greater than 6:

1.

9. The method according to claim 5, characterized in that, In step S1, after forging or rolling, the bar stock is further subjected to spheroidizing annealing at 780~850°C. The carbide inhomogeneity of the spheroidized annealed bar stock shall not exceed grade 1 according to the GB / T14979-1994 standard.

10. The method according to claim 5, characterized in that, In step S2, the parameters for rough machining are: spindle speed 400~700 r / min, feed rate 0.4~0.6 mm / r, machining allowance 0.3~0.4 mm in diameter and 0.4~0.5 mm in length; the cutting tool used is a carbide tool with a hardness ≥88HRA.

11. The method according to claim 5, characterized in that, In step S3, the specific process of vacuum quenching is as follows: the temperature is raised to 600~650℃ at a rate of ≤300℃ / h and held for 1~2h, then raised to 850~950℃ and held for 2~3h, then raised to 1080~1150℃ at a rate of ≤250℃ / h and held for 0.5~2h, and after the holding is completed, the temperature is cooled to 60~100℃ using inert gas with a pressure of 0.5~1.0MPa or quenching oil with a temperature of ≤80℃.

12. The method according to claim 5, characterized in that, In step S3, the cryogenic treatment is carried out at -140~-196℃ for 3~5 hours; the tempering is carried out 2~3 times, and each tempering is held at 520~620℃ for 4~6 hours and then air-cooled. Alternatively, the tempering is performed at a low temperature of 180~280°C for no less than 3 times.

13. The method according to claim 5, characterized in that, In step S4, the machining parameters of the CNC precision turning are: spindle speed 800~1300 r / min, feed rate 0.06~0.08 mm / r.

14. The method according to claim 5, characterized in that, In step S4, the external cylindrical grinding includes rough grinding and fine grinding using a cubic boron nitride grinding wheel; the grinding wheel grit size for rough grinding is 100~200 mesh, and the feed rate is 0.01~0.015 mm; the grinding wheel grit size for fine grinding is 500~600 mesh, and the feed rate is 0.001~0.005 mm; the axial movement speed for both rough grinding and fine grinding is 30~40 mm / s.

15. The method according to claim 5, characterized in that, In step S4, the internal grinding is a fine grinding, with a feed rate of 0.001~0.005mm and an axial movement speed of 40~80mm / s.

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