Test method for tufftriding infiltrated layer of workpiece

Abstract

The invention provides an inspection method for a tufftriding infiltrated layer of a workpiece. The inspection method comprises the following steps: carrying out tufftriding treatment on the workpiece; inlaying a conductive hot inlaying material into the tufftriding permeation layer; embedding the solid phase type embedding material into the tufftriding permeation layer; the workpiece is ground; the workpiece is polished; the workpiece is cleaned; and observing and measuring the thickness and hardness of the tufftriding infiltrated layer through a micro Vickers hardness tester, and if the thickness of the tufftriding infiltrated layer is greater than a thickness threshold value preset by an operator and the hardness of the tufftriding infiltrated layer is greater than a hardness threshold value preset by the operator, listing the corresponding workpieces as qualified products. By the adoption of the technical scheme, after the conductive type hot inlay material is inlaid, the edge of the workpiece is protected and prevented from being damaged, after the solid-phase type inlay material is inlaid, the significance of a boundary between a nitriding layer and a workpiece base body is improved, and inspectors are promoted to make accurate judgment and obtain accurate actual measurement data of the thickness and hardness of the nitriding layer.

Description

Technical Field

[0001] The invention belongs to the field of inspection technology, and in particular relates to a method for inspecting a soft nitriding layer of a workpiece. Background Art

[0002] Soft nitriding, also known as nitrocarburizing or ferrite nitrocarburizing, is a chemical surface heat treatment process that simultaneously infiltrates nitrogen and carbon atoms into the surface of steel parts at 500-580°C. The soft nitriding process is characterized by low treatment temperatures, a process time as short as 2-3 hours, and a wide range of applications. Generally speaking, soft nitriding can improve the surface hardness and wear resistance of workpieces, enhance fatigue resistance, and improve corrosion resistance. Its surface modification effect is significant, and the dimensional change before and after treatment is minimal, which can maintain the original precision of the part. However, nitriding also has certain limitations. Because the nitriding layer is usually shallow, approximately 0.04mm, nitrided parts may have difficulty bearing heavy loads. Therefore, for some important or critical components, the thickness or hardness of the nitriding layer on the surface of the soft nitrided component needs to be tested to ensure the performance of the component.

[0003] For example, the patent document with publication number "CN217059630U" discloses a crankshaft nitriding hardness testing device, including a workbench and a detector body, an electric telescopic rod is installed on the upper wall of the workbench, and the detector body is installed on the upper wall of the electric telescopic rod, a support is installed on the upper wall of the workbench, a cleaning mechanism is installed on the upper wall of the support, a slide rail is installed on the upper wall of the slide rail, an electric movable platform is slidably installed on the upper wall of the slide rail, a chuck is installed on the side wall of the electric movable platform, and a bracket is installed on the upper wall of the electric movable platform. After the fan in the cleaning mechanism is powered on, the wind generated is ejected through the nozzle on the inner side of the annular plate, so that it blows off impurities such as iron filings on the surface of the crankshaft to avoid affecting the test results during testing. In addition, a transparent baffle is set on the side wall of the workbench, so that the baffle can block impurities when the cleaning mechanism cleans the crankshaft, to avoid impurities such as iron filings flying out and causing harm to the staff.

[0004] However, due to the extremely thin thickness of the nitride layer, it is not easy to distinguish the workpiece substrate from the nitride layer even when observing it with a microscope, and it is even more difficult to accurately measure the thickness of the nitride layer. In addition, the thickness of the nitride layer is extremely thin. If the operator does not accurately distinguish the boundary between the workpiece substrate and the nitride layer, the hardness tester will penetrate the nitride layer and can only measure the hardness of the workpiece substrate, but not the hardness of the nitride layer. Summary of the Invention

[0005] In order to solve the above technical problems, the present invention provides a method for inspecting the soft nitriding layer of a workpiece.

[0006] The present invention is achieved through the following technical solutions.

[0007] The present invention provides a method for inspecting a soft nitriding layer of a workpiece, comprising the following steps:

[0008] Step 1: providing a workpiece, performing a soft nitriding treatment on the workpiece, and obtaining a soft nitriding layer on the surface of the workpiece;

[0009] Step 2: Using a mounting machine to mount a conductive hot-mounted mounting material into the soft nitriding layer;

[0010] Step 3: using a setting machine to set the solid phase setting material in the soft nitriding layer;

[0011] Step 4: grinding the workpiece;

[0012] Step 5: polishing the workpiece;

[0013] Step 6: Cleaning the workpiece;

[0014] Step 7: Observe and measure the thickness and hardness of the soft nitriding layer using a micro Vickers hardness tester. If the thickness of the soft nitriding layer is greater than the thickness threshold set by the operator and the hardness of the soft nitriding layer is greater than the hardness threshold set by the operator, the corresponding workpiece is classified as a qualified product.

[0015] The process parameters for step 2 or step 3 are as follows:

[0016] The model of the mounting machine is CitoPress-5 or CitoPress-30; the mounting process of the conductive hot mounting material or solid phase mounting material includes three stages: heating, heat preservation and pressure holding, and cooling. Among them, the temperature of the heat preservation and pressure holding stage is 180°C, the pressure is 350 bar, and the duration of the cooling stage is not less than 2 minutes.

[0017] The conductive hot-mounting material in step 2 is HMR2 hot-mounting material.

[0018] The solid phase mounting material described in step 3 is MultiFast metallographic mounting material.

[0019] In step 4, the process parameters for grinding the workpiece are as follows:

[0020] The model of the grinding machine is Tegramin-25. The grinding machine is equipped with a grinding disc made of granular silicon carbide. The grinding process is divided into several grinding steps, each of which lasts for 0.5-1 minute. Water is used as a lubricant to lubricate the workpiece surface in each grinding step. The spindle speed of the grinding machine is 150r / min in each grinding step, and the grinding disc speed is 300r / min in each grinding step. The particle size of the silicon carbide gradually increases with the progress of each step.

[0021] The particle size of the silicon carbide is 180 mesh to 4000 mesh.

[0022] In step 5, the process parameters for polishing the workpiece are as follows:

[0023] The model of the polishing machine is Tegramin-25. The polishing machine is equipped with a polishing disk made of MD-Dac. During the polishing process, 1 μm diamond is used as a lubricant to lubricate the workpiece surface. The polishing process lasts for 1-3 minutes. The spindle speed of the polishing machine is 150 r / min, and the speed of the polishing disk is 230 r / min.

[0024] In step six, cleaning the workpiece means:

[0025] Step 1: Rinse the workpiece with clean water and then blow dry the workpiece;

[0026] Step 2: Prepare a cleaning agent by mixing 5% nitric acid and alcohol in advance, and store the cleaning agent in a sealed container for at least 24 hours.

[0027] Step 3: Cleaning the workpiece with a cleaning agent;

[0028] Step 4: After cleaning the workpiece twice with clean water, spray alcohol on the surface of the workpiece and then blow dry the workpiece.

[0029] In step seven, the thickness threshold is 0.01-0.02 mm.

[0030] In step seven, the hardness threshold is 1000-1200 HV.

[0031] The beneficial effects of the present invention are as follows: by adopting the technical solution of the present invention, after first embedding a conductive hot embedding material into the soft nitriding layer, the edge of the workpiece is protected, the edge of the workpiece can be prevented from being damaged, and the inspector can accurately observe the nitriding layer through a microscope; after embedding a solid-phase embedding material into the nitriding layer, the metallographic structure in the nitriding layer maintains good shape stability and consistency, thereby improving the significance of the boundary line between the nitriding layer and the workpiece substrate, allowing the inspector to observe the clear boundary between the nitriding layer and the workpiece substrate through a microscope, prompting the inspector to make accurate judgments, obtain accurate measured data on the thickness and hardness of the nitriding layer, prevent unqualified workpieces from entering the market, and reduce safety hazards. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 It is a process flow chart of the present invention;

[0033] Figure 2The workpiece is made of 38CrMoAlA and is observed and photographed under a microscope after the workpiece soft nitriding layer inspection method provided by the present invention is adopted. DETAILED DESCRIPTION

[0034] The technical solution of the present invention is further described below, but the scope of protection claimed is not limited to the description.

[0035] like Figure 1 、 Figure 2 As shown, the present invention provides a method for inspecting a soft nitriding layer of a workpiece, comprising the following steps:

[0036] Step 1: providing a workpiece, performing a soft nitriding treatment on the workpiece, and obtaining a soft nitriding layer on the surface of the workpiece;

[0037] Step 2: Using a mounting machine to mount a conductive hot-mounted mounting material into the soft nitriding layer;

[0038] Step 3: using a setting machine to set the solid phase setting material in the soft nitriding layer;

[0039] Step 4: grinding the workpiece;

[0040] Step 5: polishing the workpiece;

[0041] Step 6: Cleaning the workpiece;

[0042] Step 7: Observe and measure the thickness and hardness of the soft nitriding layer using a micro Vickers hardness tester. If the thickness of the soft nitriding layer is greater than the thickness threshold set by the operator and the hardness of the soft nitriding layer is greater than the hardness threshold set by the operator, the corresponding workpiece is classified as a qualified product.

[0043] By adopting the technical solution of the present invention, a conductive hot-dip inlay is first inlaid into the soft nitriding layer, which has a protective effect on the edge of the workpiece and can prevent the edge of the workpiece from being damaged, so that the inspector can accurately observe the nitriding layer through a microscope; and after a solid-phase inlay is then inlaid into the nitriding layer, the metallographic structure in the nitriding layer maintains good shape stability and consistency, thereby improving the significance of the boundary line between the nitriding layer and the workpiece substrate, so that the inspector can observe the clear boundary between the nitriding layer and the workpiece substrate through a microscope, prompting the inspector to make accurate judgments, obtain accurate measured data on the thickness and hardness of the nitriding layer, prevent unqualified workpieces from entering the market, and reduce safety hazards.

[0044] Furthermore, the workpiece soft nitriding layer inspection method also includes the following steps: when performing step seven, if the thickness of the soft nitriding layer is less than the thickness threshold preset by the operator, or the hardness of the soft nitriding layer is less than the hardness threshold preset by the operator, the corresponding workpiece is listed as unqualified.

[0045] Specifically, the process parameters for step 2 or step 3 are as follows:

[0046] The mounting machine model is CitoPress-5 or CitoPress-30. The mounting process for the conductive hot-mounting material or solid-phase mounting material includes three stages: heating, holding and pressurizing, and cooling. The holding and pressurizing stage is set at a temperature of 180°C and a pressure of 350 bar, and the cooling stage lasts for no less than 2 minutes. The conductive hot-mounting material used in step 2 is HMR2 hot-mounting material. The solid-phase mounting material used in step 3 is MultiFast metallographic mounting material.

[0047] In addition, in step 4, the process parameters for grinding the workpiece are as follows:

[0048] The model of the grinding machine is Tegramin-25. The grinding machine is equipped with a grinding disc made of granular silicon carbide. The grinding process is divided into several grinding steps, each lasting 0.5-1 minute. Water is used as a lubricant to lubricate the workpiece surface in each grinding step. The spindle speed of the grinding machine is 150 rpm in each grinding step, and the grinding disc speed is 300 rpm in each grinding step. The particle size of the silicon carbide is gradually increased with the progress of each step. Preferably, the particle size of the silicon carbide is 180 mesh to 4000 mesh.

[0049] In step 5, the process parameters for polishing the workpiece are as follows:

[0050] The model of the polishing machine is Tegramin-25. The polishing machine is equipped with a polishing disk made of MD-Dac. During the polishing process, 1 μm diamond is used as a lubricant to lubricate the workpiece surface. The polishing process lasts for 1-3 minutes. The spindle speed of the polishing machine is 150 r / min, and the speed of the polishing disk is 230 r / min.

[0051] In addition, in step six, cleaning the workpiece refers to:

[0052] Step 1: Rinse the workpiece with clean water and then blow dry the workpiece;

[0053] Step 2: Prepare a cleaning agent by mixing 5% nitric acid and alcohol in advance, and store the cleaning agent in a sealed container for at least 24 hours.

[0054] Step 3: Cleaning the workpiece with a cleaning agent;

[0055] Step 4: After cleaning the workpiece twice with clean water, spray alcohol on the surface of the workpiece and then blow dry the workpiece.

[0056] The material of the workpiece is 38CrMoAlA, and the workpiece is a gear. In step 7, the thickness threshold is 0.01-0.02 mm. In step 7, the hardness threshold is 1000-1200 HV.

[0057] By adopting the technical solution of the present invention, the workpiece is cleaned twice in succession to completely remove the debris attached to the surface of the workpiece, and the cleaning agent is sealed and stored for at least 24 hours to allow the nitric acid and alcohol to be fully mixed and dissolved, and to prevent impurities such as oxygen and water vapor in the external environment from entering the solution, thereby avoiding the deterioration of the cleaning agent. When the cleaning agent is used to clean the workpiece, the cleaning agent will not corrode the nitride layer, but will corrode and remove the workpiece matrix elements attached to the inside of the nitride layer, thereby making the boundary line between the workpiece matrix and the nitride layer clearer and more significant. After the workpiece is cleaned with the cleaning agent and clean water, alcohol is sprayed on the surface of the workpiece, and the alcohol and the small water droplets attached to the surface of the nitride layer are completely dissolved, and the small water droplets attached to the surface of the nitride layer are completely removed by volatilization, thereby avoiding the appearance of colored water marks on the surface of the nitride layer, laying a foundation for improving the inspection accuracy.

[0058] Figure 2 The workpiece material is 38CrMoAlA. After the workpiece soft nitriding layer inspection method provided by the present invention is used, the workpiece is observed and photographed under a microscope. Figure 2 As shown, the white area on the left side of the picture is the nitride layer, and the remaining dark areas are the workpiece substrate. It can be seen that after adopting the technical solution of the present invention, the dividing line between the nitride layer and the workpiece substrate is very clear and obvious, which helps the inspectors to distinguish the nitride layer from the workpiece substrate, thereby improving the inspection accuracy of the nitride layer thickness and hardness, and improving the reliability of the inspection data.

Claims

1. A method for inspecting a soft nitriding layer of a workpiece, characterized in that: The following steps are involved: Step 1: providing a workpiece, performing a soft nitriding treatment on the workpiece, and obtaining a soft nitriding layer on the surface of the workpiece; Step 2: Using a mounting machine to mount a conductive hot-mounting material into the soft nitriding layer; Step 3: Using a setting machine to set the solid phase setting material into the soft nitriding layer; Step 4: grinding the workpiece; Step 5: polishing the workpiece; Step 6: Cleaning the workpiece; Step 7: Observe and measure the thickness and hardness of the soft nitriding layer using a micro Vickers hardness tester. If the thickness of the soft nitriding layer is greater than the thickness threshold set by the operator and the hardness of the soft nitriding layer is greater than the hardness threshold set by the operator, the corresponding workpiece is classified as a qualified product.

2. The method for inspecting the soft nitriding layer of a workpiece according to claim 1, wherein: The process parameters for step 2 or step 3 are as follows: The model of the mounting machine is CitoPress-5 or CitoPress-30; the mounting process of the conductive hot mounting material or solid phase mounting material includes three stages: heating, heat preservation and pressure holding, and cooling. Among them, the temperature of the heat preservation and pressure holding stage is 180°C, the pressure is 350 bar, and the duration of the cooling stage is not less than 2 minutes.

3. The method for inspecting the soft nitriding layer of a workpiece according to claim 1 or 2, wherein: The conductive hot-mounting material in step 2 is HMR2 hot-mounting material.

4. The method for inspecting the soft nitriding layer of a workpiece according to claim 1 or 2, wherein: The solid phase mounting material described in step 3 is MultiFast metallographic mounting material.

5. The method for inspecting the soft nitriding layer of a workpiece according to claim 1, wherein: In step 4, the process parameters for grinding the workpiece are as follows: The model of the grinding machine is Tegramin-25. The grinding machine is equipped with a grinding disc made of granular silicon carbide. The grinding process is divided into several grinding steps, each of which lasts for 0.5-1 minute. Water is used as a lubricant to lubricate the workpiece surface in each grinding step. The spindle speed of the grinding machine is 150r / min in each grinding step, and the grinding disc speed is 300r / min in each grinding step. The particle size of the silicon carbide gradually increases with the progress of each step.

6. The method for inspecting the soft nitriding layer of a workpiece according to claim 5, wherein: The particle size of the silicon carbide is 180 mesh to 4000 mesh.

7. The method for inspecting the soft nitriding layer of a workpiece according to claim 1, wherein: In step 5, the process parameters for polishing the workpiece are as follows: The model of the polishing machine is Tegramin-25. The polishing machine is equipped with a polishing disk made of MD-Dac. During the polishing process, 1 μm diamond is used as a lubricant to lubricate the workpiece surface. The polishing process lasts for 1-3 minutes. The spindle speed of the polishing machine is 150 r / min, and the speed of the polishing disk is 230 r / min.

8. The method for inspecting the soft nitriding layer of a workpiece according to claim 1, wherein: In step six, cleaning the workpiece means: Step 1: Rinse the workpiece with clean water and then blow dry the workpiece; Step 2: Prepare a cleaning agent by mixing 5% nitric acid and alcohol in advance, and store the cleaning agent in a sealed container for at least 24 hours. Step 3: Cleaning the workpiece with a cleaning agent; Step 4: After cleaning the workpiece twice with clean water, spray alcohol on the surface of the workpiece and then blow dry the workpiece.

9. The method for inspecting the soft nitriding layer of a workpiece according to claim 1, wherein: In step seven, the thickness threshold is 0.01-0.02 mm.

10. The method for inspecting the soft nitriding layer of a workpiece according to claim 1, wherein: In step seven, the hardness threshold is 1000-1200 HV.

Images