Composite workpiece machining method and composite workpiece

Abstract

The embodiment of the invention discloses a workpiece combined machining method. The workpiece combined machining method comprises the steps that a to-be-sulfurized area on the surface of a nitriding layer of a prefabricated workpiece is covered with a sulfurizing agent; the surface, covered with the sulfurizing agent, of the prefabricated workpiece is ground at the preset temperature, so that a sulfurizing layer is generated on the prefabricated workpiece, and a composite workpiece is obtained; the prefabricated workpiece is a workpiece containing a nitriding layer. According to the embodiment of the invention, the sulfurizing layer is generated on the surface of the nitriding layer of the prefabricated workpiece, so that the adhesive wear resistance of the surface of the workpiece is effectively improved. Meanwhile, sulfurizing and grinding are combined, so that the production efficiency is improved, and the process complexity is effectively reduced.

Description

Technical Field

[0001] The present invention relates to the field of precision machining, and particularly to a composite workpiece and a method for machining a composite workpiece. Background Art

[0002] In the surface treatment process of metal materials, sulfurizing treatment is often used to improve the performance of workpieces. In traditional sulfurizing processes, salt bath sulfurizing is a common choice. In terms of process operation, it is necessary to first perform precision grinding on the nitrided surface of the workpiece, then apply a coating to protect the non-sulfurized area, and then place the entire workpiece in a salt bath for sulfurizing. After sulfurizing is completed, precision grinding is performed again. The process is cumbersome and complex. Moreover, for large-sized workpieces, it is necessary to build a large salt bath, which is costly. Summary of the Invention

[0003] In view of at least some of the problems and deficiencies in the prior art, embodiments of the present invention disclose a composite workpiece and a method for machining a composite workpiece, effectively improving the anti-adhesive wear resistance of the workpiece surface.

[0004] On the one hand, a method for machining a composite workpiece provided by an embodiment of the present invention includes: covering a sulfurizing agent on a sulfurizing area on the nitrided layer surface of a prefabricated workpiece. Performing grinding machining treatment on the surface of the prefabricated workpiece covered with the sulfurizing agent at a preset temperature to form a sulfurized layer on the prefabricated workpiece to obtain a composite workpiece. The prefabricated workpiece is a workpiece containing a nitrided layer.

[0005] In an embodiment of the present invention, the covering of the sulfurizing agent on the sulfurizing area on the nitrided layer surface of the prefabricated workpiece specifically includes: applying a mixture of an aqueous solvent and the sulfurizing agent to the sulfurizing area.

[0006] In an embodiment of the present invention, the covering of the sulfurizing agent on the sulfurizing area on the nitrided layer surface of the prefabricated workpiece specifically includes: continuously feeding sulfurizing agent powder to the sulfurizing area.

[0007] In an embodiment of the present invention, the sulfurizing agent is covered on the sulfurizing area on the nitrided layer surface multiple times.

[0008] In an embodiment of the present invention, the preset temperature is 195°C to 205°C.

[0009] In an embodiment of the present invention, the sulfurizing agent includes KSCN and Al 2 K 2 (SO 4 ) 4 ·24H 2 O.

[0010] In an embodiment of the present invention, the proportion of KSCN in the sulfurizing agent is 10% to 15%, and the Al 2 K2 (SO 4 ) 4 ·24H 2 O accounts for 85% - 90% of the specific gravity of the sulfurizing agent.

[0011] In an embodiment of the present invention, the method for composite machining of a workpiece further includes: controlling the grinding depth of cut, the workpiece feed rate, and the grinding wheel linear speed so that the grinding temperature of the area to be sulfurized during the grinding process reaches the preset temperature. The grinding depth of cut, the workpiece feed rate, and the grinding wheel linear speed satisfy the following relationship with the grinding temperature:

[0012]

[0013] where T is the maximum temperature rise during grinding, a is the grinding depth of cut, v w is the workpiece feed rate, v s is the grinding wheel linear speed, d e is the equivalent diameter of the grinding wheel, α is the thermal diffusivity, k is the thermal conductivity, u is the specific grinding energy, u ch is the chip formation energy.

[0014] On the other hand, a composite workpiece provided by an embodiment of the present invention is made by the method for composite machining of a workpiece according to any one of the foregoing embodiments. The composite workpiece includes a substrate, a nitrided layer, and a sulfurized layer, and the nitrided layer and the sulfurized layer are located on the substrate.

[0015] In an embodiment of the present invention, the sulfurized layer is Fe 2 S, FeS, or a mixture of Fe 2 S and FeS.

[0016] As can be seen from the above, one or more of the above technical features of the present invention can have the following beneficial effects:

[0017] 1. By sulfurizing only the area to be sulfurized of the workpiece during grinding, putting the entire workpiece into a salt bath for sulfurizing is avoided, precise control of the sulfurizing range is achieved, and only the parts that need to be sulfurized can be processed according to the specific requirements of the workpiece, reducing unnecessary processing procedures and costs. At the same time, protecting treatments such as copper plating on the surfaces that do not need to be sulfurized are avoided, simplifying the process, and reducing production costs and process complexity.

[0018] 2. Directly performing grinding-assisted sulfurizing after nitriding, combining sulfurizing with grinding processing, reduces multiple grinding and other procedures before and after sulfurizing in the traditional process, shortens the processing cycle, and improves production efficiency.

[0019] 3. After nitriding treatment, the strength and hardness of the workpiece surface can be significantly improved. Sulfurizing the nitrided layer surface not only improves the surface quality and anti-adhesive wear resistance of the workpiece, but also effectively reduces the friction coefficient. Brief Description of the Drawings

[0020] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for the description of the embodiments will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0021] Figure 1 It is a schematic flow chart of a method for machining a composite workpiece provided by an embodiment of the present invention.

[0022] Figure 2 It is a schematic diagram for comparing the friction coefficients of ordinary grinding and assisted sulfurizing grinding of a prefabricated workpiece containing a nitrided layer.

[0023] Figure 3 It is a schematic diagram of the grinding surface morphology of the nitrided layer of a prefabricated workpiece under a scanning electron microscope.

[0024] Figure 4 It is a schematic diagram of the surface morphology of the nitrided layer of a prefabricated workpiece after assisted sulfurizing grinding under a scanning electron microscope. Detailed Embodiments

[0025] To make the objectives, technical solutions, and advantages of the present invention clearer, the technical solutions of the present invention will be clearly and completely described below in conjunction with the specific embodiments of the present invention and the corresponding drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the scope of protection of the present invention.

[0026] It should be noted that the terms "first", "second", etc. in the description and claims of the present invention and the above drawings are used to distinguish similar objects, and do not necessarily describe a specific order or sequence. It should be understood that such terms can be interchanged under appropriate circumstances so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "include" and "have" and any variations thereof are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or device that includes a series of steps or units does not necessarily have to be limited to those steps or units clearly listed, but may include other steps or units not clearly listed or inherent to these processes, methods, products, or devices.

[0027] It should also be noted that the division of multiple embodiments in the present invention is only for convenience of description and should not constitute a special limitation. Features in various embodiments can be combined with each other and cited from each other without contradiction.

[0028] On the one hand, as shown in Figure 1 A method for compound processing a workpiece provided by an embodiment of the present invention includes: covering a sulfurizing agent on a sulfurizing region on the nitrided layer surface of a prefabricated workpiece. The surface of the prefabricated workpiece covered with the sulfurizing agent is subjected to grinding processing at a preset temperature to generate a sulfurized layer on the prefabricated workpiece to obtain a composite workpiece. The prefabricated workpiece is a workpiece containing a nitrided layer.

[0029] Specifically, when preparing the prefabricated workpiece, a nitrided layer with a thickness of 0.1 mm to 0.2 mm needs to be reserved on the surface of the workpiece for subsequent sulfurizing treatment during grinding. Exemplarily, the thickness of the nitrided layer of the prefabricated workpiece is 0.3 mm to 0.4 mm, and the nitrided layer obtained after sulfurizing treatment during grinding is 0.2 mm. The method of sulfurizing treatment during grinding in the present invention can also be called a grinding-assisted sulfurizing method, a grinding sulfurizing method or an assisted sulfurizing grinding method, where the preset temperature refers to the temperature when grinding the region on the prefabricated workpiece covered with the sulfurizing agent. Finally, a sulfurized layer is generated on the prefabricated workpiece to obtain a composite workpiece, that is, the composite workpiece is a workpiece with a nitrided layer and a sulfurized layer on the substrate.

[0030] In the related art, the single sulfurizing process is only applicable to workpieces with light loads and low-speed movements, such as sliding bearings, low-speed gearboxes, stamping dies, rock drill pistons, cylinder sleeves, etc. However, in the grinding-assisted sulfurizing method of the present invention, sulfur elements in the sulfurized layer generated on the prefabricated workpiece penetrate into the nitrided layer, that is, the nitrided layer and the sulfurized layer formed on the obtained composite workpiece can be called a nitrogen-sulfur composite layer. The nitrogen-sulfur composite layer can expand the sulfurizing process, making the sulfurizing process no longer limited to specific types of workpieces and capable of being applied to parts under a wider range of working conditions and working conditions, such as parts that can withstand higher loads and high-speed movements, improving the reliability and adaptability of the parts in different working environments.

[0031] Related technologies show that a single sulfurized layer has good antifriction properties and can effectively reduce the friction coefficient of the workpiece surface. Its microstructural and chemical composition characteristics enable it to act like a lubricant during the friction process, reducing the friction force between surfaces, preventing direct contact between metal surfaces, and thus inhibiting the occurrence of adhesive wear. As shown in Figure 3 and Figure 4As shown, it can be seen under a scanning electron microscope that after the grinding-assisted sulfurizing treatment of the nitrided layer of the prefabricated workpiece, the surface grinding marks are regular, with few fractures in the middle, and the morphology is superior to that of the ground surface of the nitrided layer of the prefabricated workpiece. In the present invention, by combining nitriding and sulfurizing, the advantages of the nitrided layer in improving the surface strength and hardness of the workpiece are retained, the friction is reduced, and part biting is prevented. At the same time, the sulfurized layer is used to improve the anti-adhesion performance of the surface, so that the workpiece can adapt to a working environment with higher load and higher speed.

[0032] During the process of covering the sulfurizing agent on the sulfurizing area on the surface of the nitrided layer of the prefabricated workpiece, it is only necessary to cover the sulfurizing agent on the sulfurizing area, avoiding unnecessary treatment of the areas that do not need sulfurizing, reducing the process steps, lowering the cost, and at the same time improving the stability and reliability of the product quality. In the related art, salt bath sulfurizing requires a large amount of salt bath materials. The present invention can accurately control the sulfurizing area, resulting in a significant reduction in the usage amount of the sulfurizing agent, effectively reducing the material cost. At the same time, since there is no need to protect the non-sulfurized areas (such as copper plating), the cost of the protective materials is also saved. Combining sulfurizing with grinding processing avoids complicated and complex process flows, shortens the processing cycle, and improves the production efficiency.

[0033] In the embodiment of the present invention, the covering of the sulfurizing agent on the sulfurizing area on the surface of the nitrided layer of the prefabricated workpiece specifically includes: applying the mixture after mixing the aqueous solvent and the sulfurizing agent to the sulfurizing area. Preferably, the aqueous solvent can be selected as a polyvinyl alcohol solution. In this embodiment, the sulfurizing agent and the polyvinyl alcohol solution are mixed into a paste and applied to the sulfurizing area to form a sulfur coating. After the sulfur coating is dried and there are no obvious cracks on the surface, grinding processing is continued. Among them, the thickness of the sulfurizing agent coating can be between 1.5 mm and 2.5 mm. Preferably, the thickness of the sulfur coating is 2 mm.

[0034] Applying the mixed paste to the sulfurizing area is more flexible than other sulfurizing methods that require special equipment or complex processes, and can adapt to workpieces with complex shapes. The polyvinyl alcohol solution has good adhesion performance. After being mixed with the sulfurizing agent, it can make the sulfurizing agent firmly and evenly adhere to the sulfurizing area on the surface of the nitrided layer. At the same time, it enhances the bonding force between the sulfurized layer and the substrate, which helps sulfur atoms to better diffuse into the workpiece. A sulfur coating with a thickness of preferably 2 mm can provide sufficient sulfurizing agent, ensuring effective control of the material cost on the premise of good sulfurizing effect.

[0035] In an embodiment of the present invention, covering the sulfurizing agent on the sulfurizing region on the surface of the nitrided layer of the prefabricated workpiece specifically includes: continuously feeding the sulfurizing agent powder to the sulfurizing region. In this embodiment, a powder feeding device can be set on the grinding machine for continuous powder feeding, specifically, continuously feeding the powder to the sulfurizing region during the grinding process without stopping the grinding. This effectively avoids the equipment idleness and production stagnation time caused by the process conversion, and improves the utilization rate of the equipment and the production efficiency. The powder feeding device is synchronized with the grinding process in real time, so that the sulfurizing agent can be quickly covered while the workpiece surface is being ground, enabling the sulfurizing agent powder to react with the grinding surface of the metal in a timely manner, which helps to improve the uniformity and consistency of the sulfurizing effect.

[0036] In an embodiment of the present invention, the sulfurizing agent is covered on the sulfurizing region on the surface of the nitrided layer multiple times. During the grinding process, it can be selected to cover the sulfurizing agent on the sulfurizing region only once during the grinding process, or it can be selected to cover the sulfurizing agent on the sulfurizing region repeatedly multiple times during the grinding process. In actual production, the number of sulfurizing times can be selected according to different workpiece materials, shapes, sizes, and specific usage conditions.

[0037] Table 1 Parameter comparison of single coverage and multiple coverage of sulfurizing agent during grinding

[0038] Surface sulfur element content Single - covering sulfurizing agent 0.1％ Multiple - covering sulfurizing agent 0.1％～0.5％

[0039] As can be seen from Table 1, the content of sulfur element can be obtained through energy spectrum analysis by scanning electron microscope. After the prefabricated workpiece is covered with the sulfurizing agent once, the surface sulfur element content is about 0.1%. After the prefabricated workpiece is covered with the sulfurizing agent multiple times, the sulfur element content is in the range of greater than or equal to 0.1% and less than 0.5%.

[0040] In an embodiment of the present invention, the preset temperature is 195°C to 205°C. Preferably, the preset temperature is 200°C. In the related art, the penetrant of the powder sulfurizing process needs to be used in the temperature range of 560°C to 930°C, but too high a temperature causes the phase change of the prefabricated workpiece made of steel, affecting the performance of the steel. Exemplarily, the penetrant of the powder sulfurizing process can be, for example, the first one is 40% S, 59% Al 2 O 3 and 1% NH 4 Cl, and the second one is 75% FeS, 20% Al 2 O 3 and 5% NH 4 Cl. In the present invention, the preset temperature is preferably 200°C, so that sulfurizing is carried out at a relatively low temperature, effectively avoiding the steel phase change problem caused by high temperature, and ensuring that the organizational structure and performance of the material matrix are not affected.

[0041] In an embodiment of the present invention, the components of the sulfurizing agent are KSCN and Al 2 K 2 (SO 4 ) 4 ·24H 2 O. KSCN serves as the sulfur source in the sulfurizing agent and can decompose to generate sulfur atoms during the sulfurizing process, providing the required sulfur element for the sulfurizing reaction on the metal surface. Secondly, the sulfur atoms generated by the decomposition of KSCN have moderate reactivity, which can ensure that the sulfur atoms have sufficient chemical driving force on the metal surface to chemically react with metal atoms to form metal sulfides, thus realizing the sulfurizing process. At the same time, the moderate reactivity can avoid the overly violent reaction of sulfur atoms, resulting in the formation of an uneven and loose sulfurizing layer on the metal surface. Al 2 K 2 (SO 4 ) 4 ·24H 2 O plays the role of an auxiliary agent in the sulfurizing agent and can promote the diffusion of sulfur atoms on and inside the metal surface. At the same time, Al 2 K 2 (SO 4 ) 4 ·24H 2 O can also improve the quality of the sulfurizing layer and enhance the performance of the sulfurizing layer.

[0042] The components of the sulfurizing agent are KSCN and Al 2 K 2 (SO 4 ) 4 ·24H 2 O have good stability at low temperatures. KSCN can exist relatively stably at low temperatures, and its decomposition rate can be effectively controlled, thus ensuring a continuous and stable supply of sulfur source during the low-temperature sulfurizing process. Al 2 K 2 (SO 4 ) 4 ·24H 2 O can continuously play its role in promoting the diffusion of sulfur atoms and improving the quality of the sulfurizing layer during the low-temperature sulfurizing process.

[0043] Specifically, the proportion of KSCN in the sulfurizing agent is 10% - 15%, and the Al 2 K 2 (SO 4 ) 4 ·24H 2O accounts for 85% - 90% of the specific gravity of the sulfurizing agent. The component ratio within this range can ensure the stability of the sulfurizing agent during storage and use, and it is not prone to problems such as decomposition and deterioration. Thus, it ensures the stability and reliability of the sulfurizing effect, providing a guarantee for obtaining a stable and high-quality sulfurized layer. At the same time, this sulfurizing agent can effectively reduce the cost of the sulfurizing agent while ensuring good sulfurizing effects and high-quality sulfurized layers, achieving an optimal balance between cost and performance.

[0044] In the embodiments of the present invention, the grinding depth of cut, the workpiece feed rate, and the grinding wheel linear speed are controlled so that the grinding temperature in the area to be sulfurized during the grinding process reaches the preset temperature. The grinding depth of cut, the workpiece feed rate, and the grinding wheel linear speed and the maximum grinding temperature rise satisfy the following relational formula:

[0045]

[0046] where T is the maximum grinding temperature rise, a is the grinding depth of cut, v w is the workpiece feed rate, v s is the grinding wheel linear speed, d e is the equivalent diameter of the grinding wheel, α is the thermal diffusivity, k is the thermal conductivity, u is the specific grinding energy, u ch is the chip formation energy. The specific grinding energy is associated with the grinding wheel speed. The specific grinding energy for grinding steel is generally 20 - 60 J / mm 3 , and for steel materials, generally u ch ≈13.8 J / mm 3 .

[0047] Exemplarily, if the grinding temperature is defined as a fixed value, that is, the temperature for grinding-assisted sulfurizing, then the above relational formula is:

[0048]

[0049] where, α is the thermal diffusivity, k is the thermal conductivity. For the same material, α and k are constants. The specific grinding energy u limited by the maximum grinding temperature rise has a linear relationship with . By reasonably combining the grinding depth of cut a, the workpiece feed rate v w , the grinding wheel linear speed v s , the equivalent diameter of the grinding wheel d e , it can ensure that the temperature in the grinding area remains constant, that is, it ensures the stable progress of grinding-assisted sulfurizing.

[0050] Precise control of the temperature during grinding is achieved by controlling the wheel linear speed, workpiece feed speed, and grinding depth of cut during grinding, so that the temperature during the grinding process is around 200 °C, and the grinding-assisted sulfurizing method can be carried out efficiently. Among them, the grinding depth of cut needs to be controlled at about 5 μm, which is the range of precision machining. The equivalent wheel diameter and the value of the contact arc length in the grinding zone can be given according to the grinding machine used, and can be calculated based on the wheel diameter and the type of grinding method. Exemplarily, the grinding method can be, for example, surface grinding, cylindrical grinding, and internal grinding. Exemplarily, taking a workpiece made of 38CrMoAlA nitriding steel as an example, a grinding depth of 5 μm, a workpiece feed speed of 6 m / min, a wheel linear speed of 30 m / s, an equivalent wheel diameter of 200 mm, and a contact arc length in the grinding zone of 1 mm are selected. After the prefabricated workpiece is subjected to ordinary grinding and the grinding-assisted sulfurizing method respectively, the measured friction coefficient results of the prefabricated workpiece and the composite workpiece are referred to Figure 2 As shown, the friction coefficient of the composite workpiece is smaller than that of the prefabricated workpiece, and the grinding-assisted sulfurizing method effectively improves the friction coefficient of the surface of the prefabricated workpiece.

[0051] In the present invention, the grinding temperature can be precisely controlled by means of a formula. By adjusting the parameters of the wheel linear speed, workpiece feed speed, and grinding depth of cut, the grinding temperature reaches the preset temperature, ensuring that the dimensional accuracy of the workpiece reaches an extremely high level and meeting the strict requirements of the precision manufacturing industry for dimensional accuracy.

[0052] On the other hand, a composite workpiece provided by an embodiment of the present invention is obtained by the composite machining workpiece method described in any one of the foregoing embodiments. The composite workpiece includes a substrate, a nitrided layer, and a sulfurized layer, and the nitrided layer and the sulfurized layer are located on the substrate. Exemplarily, the thickness of the nitrided layer in the composite workpiece is 0.4 mm, and the thickness of the sulfurized layer is 5 μm to 10 μm.

[0053] According to the related art, the nitrides in the nitrided layer provide a high-hardness support framework, and during the friction process of the sulfurized layer, its sulfides can form a self-lubricating film on the surface, reducing the direct contact between the friction pairs and reducing the wear rate. Combining sulfurizing with nitriding effectively improves the wear resistance of the workpiece and the anti-adhesion performance of the surface. When the nitrogen-sulfur composite layer is applied to high-speed rotating mechanical components and transmission workpieces under heavy loads, it can ensure high strength and high hardness of the workpiece while providing good anti-adhesion performance, ensuring stable and reliable operation of the workpiece under complex working conditions, and expanding the application scenarios and service life of the workpiece.

[0054] In an embodiment of the present invention, the sulfurized layer is Fe 2 S, FeS, or Fe 2 A mixture of S and FeS. Fe 2Both S and FeS have good lubrication performance. Sulfur atoms in the crystal structure can form a lubricating film on the material surface. During the friction process, this lubricating film can effectively reduce the direct contact between the friction pairs, thereby reducing the friction coefficient. At the same time, the formed lubricating film has self-lubricating characteristics and can continuously supplement and repair the lubricating film during the friction process to maintain a good lubrication state. The sulfurized layer containing Fe 2 S or FeS can form a continuous and dense protective film on the metal surface, effectively preventing the direct contact between the metal surfaces, thereby reducing the occurrence of friction and wear and preventing the appearance of adhesion phenomena.

[0055] It can be understood that the foregoing embodiments are only exemplary descriptions of the present invention. On the premise that the technical features do not conflict, the structures do not contradict, and the invention purpose of the present invention is not violated, the technical solutions of each embodiment can be arbitrarily combined and used in combination.

[0056] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements for some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of each embodiment of the present invention.

Claims

1. A method for composite processing of a workpiece, characterized in that: include: Covering the sulfurizing agent on the area to be sulfurized on the surface of the nitrided layer of the prefabricated workpiece; The surface of the prefabricated workpiece covered with the sulfurizing agent is ground at a preset temperature to generate a sulfurized layer on the prefabricated workpiece to obtain a composite workpiece; the prefabricated workpiece is a workpiece containing a nitriding layer.

2. The method for composite machining of a workpiece according to claim 1, characterized in that: The step of covering the to-be-sulfurized area on the surface of the nitrided layer of the prefabricated workpiece with a sulfurizing agent specifically comprises: The mixture of the aqueous solvent and the sulfurizing agent is applied to the area to be sulfurized.

3. The method for composite machining a workpiece according to claim 1, characterized in that: The step of covering the area to be sulfurized on the surface of the nitriding layer of the prefabricated workpiece with the sulfurizing agent specifically comprises: continuously delivering sulfurizing agent powder to the area to be sulfurized.

4. The method for composite machining a workpiece according to claim 1, characterized in that: The sulfurizing agent covers the to-be-sulfurized area on the surface of the nitriding layer for multiple times.

5. The method for composite machining a workpiece according to claim 1, characterized in that: The preset temperature is 195°C to 205°C.

6. The method for composite machining a workpiece according to claim 1, characterized in that: The sulfurizing agent includes KSCN and Al2K2(SO4)4·24H2O.

7. The method for composite machining a workpiece according to claim 6, characterized in that: The KSCN accounts for 10% to 15% of the sulfurizing agent, and the Al2K2(SO4)4·24H2O accounts for 85% to 90% of the sulfurizing agent.

8. The method for composite machining a workpiece according to claim 1, characterized in that: Also includes: Controlling the grinding cutting depth, workpiece feed speed and grinding wheel linear speed so that the grinding temperature of the area to be infiltrated reaches the preset temperature during the grinding process; The grinding depth, the workpiece feed speed, the grinding wheel linear speed and the grinding temperature satisfy the following relationship: Among them, T is the maximum temperature rise during grinding, a is the grinding cutting depth, v w is the workpiece feed speed, v s is the grinding wheel linear speed, d e is the equivalent diameter of the grinding wheel, α is the thermal diffusivity, k is the thermal conductivity, u is the specific grinding energy, u ch To become crumbs energy.

9. A composite workpiece, characterized in that: The composite workpiece is manufactured by the composite machining method according to any one of claims 1 to 8, wherein the composite workpiece comprises a substrate, a nitriding layer and a sulfiding layer, wherein the nitriding layer and the sulfiding layer are located on the substrate.

10. The composite workpiece according to claim 9, characterized in that The sulfurized layer is Fe2S, FeS or a mixture of Fe2S and FeS.

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