CN114959245A - Process method for improving surface hardness and wear resistance of G13Cr4Mo4Ni4V steel by using laser impact - Google Patents

Abstract

The invention belongs to the field of laser processing, and particularly relates to a process method for improving the surface hardness and wear resistance of G13Cr4Mo4Ni4V steel by using laser shock. The surface of G13Cr4Mo4Ni4V steel was impacted by pulsed laser with different laser power density; the surface hardness of G13Cr4Mo4Ni4V steel before and after impact was measured by HV1000A microhardness tester; The results show that the surface hardness of the G13Cr4Mo4Ni4V steel sample after laser shock is increased by about 25HV, and the wear resistance is significantly enhanced. The wear amount of the sample impacted with the best parameters is reduced by 94.47%. The optimal process parameters of laser shock G13Cr4MoNi4V steel were obtained, and the surface hardness and wear resistance of the samples impacted with these parameters were greatly improved.

Description

A process method for improving the surface hardness and wear resistance of G13Cr4Mo4Ni4V steel by using laser shock

technical field

The invention belongs to the technical field of laser shock strengthening, in particular to a process method for improving the surface hardness and wear resistance of G13Cr4Mo4Ni4V steel by utilizing laser shock.

Background technique

As we all know, the performance of bearing materials is an important factor in determining the quality of bearings. Although 8Cr4Mo4V steel has high strength and high temperature resistance, its fracture toughness is poor and fatigue cracks are prone to occur. Then, the G13Cr4Mo4Ni4V carburized bearing steel which is hard on the outside and tough on the inside was developed. However, due to the small size of the carbide particles in the carburized layer, the surface hardness is lower than that of the 8Cr4Mo4V steel, and the wear resistance is slightly poor. Laser shock strengthening technology is an emerging surface strengthening technology. Its mechanical effect causes plastic deformation of the surface material and introduces work hardening effect, which is suitable for improving the surface hardness and wear resistance of G13Cr4Mo4Ni4V carburized bearing steel.

In recent years, laser shock strengthening technology has developed rapidly. This technology can not only generate favorable residual compressive stress on the surface of metal materials, but also refine the grains of the surface layer of metal materials, and generate a large number of microstructures such as dislocations and twins. It can effectively improve the fatigue strength and wear resistance of the material surface. At the same time, the laser shock strengthening technology has the characteristics of non-contact, convenient operation, strong controllability and wide application range, so it has a good application prospect in the field of rolling bearings.

G13Cr4Mo4Ni4V, as the second-generation aviation bearing steel, is widely used in the manufacture of aviation bearings. Because its surface hardness and wear resistance need to be further improved, and in view of the superiority of laser shock strengthening technology, it is preferred to improve the surface hardness and wear resistance of G13Cr4Mo4Ni4V steel. The performance of the laser shock strengthening method is particularly important.

SUMMARY OF THE INVENTION

In view of the above problems, the purpose of the present invention is to provide a process method for improving the surface hardness and wear resistance of G13Cr4Mo4Ni4V steel by using laser shock to solve the problems of insufficient surface hardness and wear resistance of existing G13Cr4Mo4Ni4V steel bearing rings.

In order to achieve the above object, the present invention adopts the following technical solutions:

A process method for improving the surface hardness and wear resistance of G13Cr4Mo4Ni4V steel by using laser shock, comprising the following steps:

Step 1: heat treatment process on the sample;

Step 2: Grind the 10×10×10 block sample after the heat treatment process (vacuum air quenching + tempering) described in step 1 to the same roughness;

Step 3: Paste the black absorbing layer on the sample;

Step 4: Clamp the sample on the special test fixture for laser shock strengthening treatment;

Step 5: Measure the surface hardness and wear resistance of the sample after laser shock treatment;

Step 6: Measure the wear resistance of the sample after laser shock treatment;

Further, in the first step, in the heat treatment process, the quenching temperature is 1070-1090°C, the temperature is kept for 30-35 minutes, the temperature of the third tempering treatment is 540°C-560°C, and the temperature is kept for 1.5-3.5 h. A cold treatment is required before each tempering. The cold treatment temperature is -75℃~-65℃, and the temperature is kept for 2h~3h; the vacuum degree is lower than 5×10 ^-2 Pa before vacuum air quenching and heating.

Further, in the third step, the absorbing layer adopts any one of 2100FRTV type black tape, black paint or aluminum foil, and the absorbing layer is required to be closely attached to the workpiece, without air bubbles, and without impurities.

Further, in the fourth step, a laser power density of 1.974GW/cm ² -3.333GW/cm ² is used to impact the surface of the sample in a large area, and the thickness of the water film is 1-2mm.

Further, in the fourth step, the laser energy distribution adopts a flat-top distribution, the light spot is a 4mm×4mm square light spot, and the light spot adopts a 50%-75% overlap ratio.

Compared with the prior art, the advantages and beneficial effects of the present invention are as follows.

1. In the present invention, through 50%-75% overlap, the laser power density of 1.974GW/cm ² -3.333GW/cm ² is used for impact, so that the large-area laser impact effect is more uniform. The surface hardness and wear resistance of G13Cr4Mo4Ni4V bearing steel are significantly increased.

2. The present invention increases the absorption utilization rate of laser energy by closely sticking the black absorption protection layer.

3. In the present invention, the laser power density of 1.974GW/cm ² -3.333GW/cm ² is used to impact the surface of the sample in a large area, so that the hardness and wear resistance of the surface of the sample are increased, and there is no ablation phenomenon, water film The thickness is 1-2mm, which restrains the explosion shock wave and increases the peak pressure and duration of the shock wave in the direction of the target.

4. The invention adopts the laser energy beam with flat top distribution and 50%-75% overlap ratio to impact the surface of the sample, so that the surface hardness and wear resistance of the sample are uniformly increased.

Description of drawings

FIG. 1 is an impact path diagram of the process method of the present invention.

Fig. 2 is the 50% overlap ratio diagram of the technological method of the present invention.

FIG. 3 is a surface hardness diagram of Examples 1-4 of the process method of the present invention.

FIG. 4 is a graph showing the wear resistance after impact of Examples 1-4 of the process method of the present invention.

Fig. 5 is the result chart of the surface hardness of the comparative example 1-2 of the process method of the present invention.

Figure 6 is a graph of the wear resistance after impact of Comparative Examples 1-2 in the process method of the present invention.

Figure 7 is a graph of the wear resistance after impact of Comparative Examples 3-4 in the process method of the present invention.

Detailed ways

In order to make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

A process method for improving the surface hardness and wear resistance of G13Cr4Mo4Ni4V steel by using laser shock, comprising the following steps:

Step 1: Prepare 15 pieces of 10mm×10mm×10mm samples for heat treatment process. In the heat treatment process, the quenching temperature is 1070℃-1090℃, the heat preservation is 30~35min, the third tempering temperature is 540℃-560℃, and the heat preservation is 1.5h- 3.5 hours. A cold treatment is required before each tempering. The cold treatment temperature is -75℃~-65℃, and the temperature is kept for 2h~3h; the vacuum degree is lower than 5×10 ^-2 Pa before vacuum air quenching and heating.

Step 2: Use 240, 600, 1000, 2000 grit sandpaper to grind 15 pieces of 10mm×10mm×10mm block samples after the heat treatment process in step 1 to the same roughness, number A1, A2, A3, B1, B2 respectively , B2, C1, C2, C3, D1, D2, D3, E1, E2, E3, divided into five groups A, B, C, D, E.

Step 3: Groups B, C, D, and E are respectively pasted with black absorbing layers. The absorbing layers are made of 2100FRTV black tape or black paint or aluminum foil (which can absorb energy and prevent laser ablation of the surface of the workpiece), and the absorbing layers must be tightly attached Fit the workpiece, no bubbles, impurities, etc.

Step 4: Clamp the samples of groups B, C, D, and E on the special test fixture, set the laser parameters, and use the laser power density of 1.974GW/cm ² -3.333GW/cm ² to impact the sample in a large area. The connection rate is 50%-75%, the laser energy distribution adopts flat-top distribution, the water film thickness is 1-2mm, and the impact path is as shown in Figure 1.

Step 5: Move the manipulator to the clamping position, remove the workpiece, remove the absorbing layer, after micro-polishing 5-10μm, set the ferrule again in the ultrasonic cleaner to clean for 5-10min, take it out and blow dry. Test the surface hardness of the unimpacted sample and the sample after impact with different parameters, record the hardness value, and compare the surface hardness of the sample after laser shock.

Step 6: Weigh the sample 5-10 times before the friction and wear test, record the initial weight (retain four significant digits), and then install it on the fixture of the reciprocating friction and wear tester, set the vertical test force: 1kN, the number of reciprocations : 3600 times, time: 3600s, frequency: 1Hz, amplitude: 5mm, using special oil for aviation bearings, after the friction and wear test, ultrasonic cleaning, drying, weighing again, and recording the experimental data.

Example 1.

Step 1: Prepare 6 pieces of 10mm × 10mm × 10mm samples for heat treatment process. In the heat treatment process, the quenching temperature is 1090 °C, the temperature is kept for 35 minutes, and the third tempering temperature is 540 °C, and the temperature is kept for 2 h. Before each tempering, a cold treatment is required. The cold treatment temperature is -75 °C and the temperature is kept for 2.5 hours. The vacuum degree is 5×10 ^-2 Pa before vacuum air quenching heating.

Step 2: Use 240, 600, 1000, 2000 grit sandpaper to grind the 10mm × 10mm × 10mm block samples after the heat treatment process (vacuum air quenching + tempering) in step 1 to the same roughness, numbering A1, A2, A3, B1, B2, B2.

Step 3: Group A is not subjected to laser shock treatment. Group B is pasted with a black absorbing layer. The absorbing layer is made of 2100FRTV black tape (the function of absorbing energy and preventing laser ablation on the surface of the workpiece), and the absorbing layer needs to be closely attached to the workpiece. , No bubbles, no impurities, etc.

Step 4: Clamp the sample of group B in the test fixture, set the laser parameters, adjust the water film thickness to 2mm, and use the laser power density of 1.974GW/ ^cm2 to impact the sample in a large area, and the spot overlap rate is 50% (9 light spots impacted on one surface) impact path, as shown in Figure 1, and 50% overlap ratio, as shown in Figure 2.

Step 5: Move the manipulator to the clamping position, remove the workpiece, remove the absorbing layer, and after micro-polishing 10μm, place the ferrule again in the ultrasonic cleaner to clean for 10min, take it out and blow dry. Test the surface hardness of the unimpacted sample and the sample after impact with different parameters, record the hardness value, and compare the surface hardness of the sample after laser shock. The hardness of the unimpacted sample is 728.18HV, and the laser power density of 1.974GW/ ^cm2 The surface hardness of the sample is 730.88HV, as shown in Figure 3.

Step 6: Hold and weigh the sample described in Step 5 with tweezers 10 times, record the initial weight (retain four significant digits) and install it on the fixture of the reciprocating friction and wear testing machine, set the vertical test force: 1kN, reciprocating Times: 3600 times, time: 3600s, frequency: 1Hz, amplitude: 5mm, lubricated with special oil for aviation bearings, ultrasonic cleaning, drying, weighing again after the friction and wear test, and recording the experimental data again, no impact sample wear The amount of wear is 0.00595g, and the wear amount of the large-area impact sample with a laser power density of 1.974GW/cm ² is 0.00133g, as shown in Figure 4.

Example 2.

Step 1: Prepare 6 pieces of 10mm × 10mm × 10mm samples for heat treatment process. In the heat treatment process, the quenching temperature is 1090 °C, the temperature is kept for 35 minutes, and the third tempering temperature is 540 °C, and the temperature is kept for 2 h. Before each tempering, a cold treatment is required. The cold treatment temperature is -75 °C and the temperature is kept for 2.5 hours. The vacuum degree is 5×10 ^-2 Pa before vacuum air quenching heating.

Step 2: Use 240, 600, 1000, 2000 grit sandpaper to grind the 10mm × 10mm × 10mm block sample after the heat treatment process (vacuum air quenching + tempering) in step 1 to the same roughness, number A1, A2, A3, C1, C2, C3.

Step 3: Group A is not subjected to laser shock treatment. Group C is pasted with a black absorption layer. The absorption layer is made of 2100FRTV type black tape (the function of absorbing energy and preventing laser ablation of the surface of the workpiece), and the absorption layer is required to be closely attached. Workpiece, no bubbles, no impurities, etc.

Step 4: Clamp the sample of group C in the test fixture, set the laser parameters, adjust the thickness of the water film to 2mm, and use the laser power density of 2.5GW/ ^cm2 to impact the sample on a large area, and the spot overlap ratio The impact path is 50% (9 spots are impacted on one surface), as shown in Figure 1, and the 50% overlap ratio is shown in Figure 2.

Step 5: Move the manipulator to the clamping position, remove the workpiece, remove the absorbing layer, and after micro-polishing 10μm, place the ferrule again in the ultrasonic cleaner to clean for 10min, take it out and blow dry. Test the surface hardness of the unimpacted sample and the sample after impact with different parameters, record the hardness value, and compare the surface hardness of the sample after laser impact. The result is that the surface hardness of the sample after the laser power density of 2.5GW/ ^cm2 is: 740.7HV, as shown in Figure 3.

Step 6: Hold and weigh the samples A and C with tweezers for 10 times, record the initial weight (retain four significant digits), and then install it on the fixture of the reciprocating friction and wear tester, set the vertical test force: 1kN, Reciprocation times: 3600 times, time: 3600s, frequency: 1Hz, amplitude: 5mm, using special oil for aviation bearings, after the friction and wear test, ultrasonic cleaning, drying, weighing again, and recording the experimental data, the result is 2.5 The wear amount of the sample after the impact of the laser power density of GW/ ^cm2 is 0.00021g, as shown in Figure 4.

Example 3.

Step 1: Prepare 6 pieces of 10mm × 10mm × 10mm samples for heat treatment process. In the heat treatment process, the quenching temperature is 1090 °C, the temperature is kept for 35 minutes, and the third tempering temperature is 540 °C, and the temperature is kept for 2 h. Before each tempering, a cold treatment is required. The cold treatment temperature is -75 °C and the temperature is kept for 2.5 hours. The vacuum degree is 5×10 ^-2 Pa before vacuum air quenching heating.

Step 2: Use 240, 600, 1000, 2000 grit sandpaper to grind the 10mm × 10mm × 10mm block sample after the heat treatment process (vacuum air quenching + tempering) in step 1 to the same roughness, number A1, A2, A3, D1, D2, D3.

Step 3: Group A is not subjected to laser shock treatment. Group D is pasted with a black absorption layer. The absorption layer is made of 2100FRTV type black tape (the function of absorbing energy and preventing laser ablation of the surface of the workpiece), and the absorption layer is required to be closely attached. Workpiece, no bubbles, no impurities, etc.

Step 4: Clamp the samples of group D in the test fixture in step 2, set the laser parameters, adjust the water film thickness to 2mm, and use the laser power density of 2.632GW/cm ² to impact the sample in a large area, and the spot overlap ratio The impact path is 50% (9 spots are impacted on one surface), as shown in Figure 1, and the 50% overlap ratio is shown in Figure 2.

Step 5: Move the manipulator to the clamping position, remove the workpiece, remove the absorbing layer, and after micro-polishing 10μm, place the ferrule again in the ultrasonic cleaner to clean for 10min, take it out and blow dry. Test the surface hardness of the unimpacted sample and the sample after impact with different parameters, record the hardness value, and compare the surface hardness of the sample after laser impact. The result is that the surface hardness of the sample after the laser power density of 2.632GW/ ^cm2 is: 735.36HV, as shown in Figure 3.

Step 6: Hold and weigh the samples A and D with tweezers for 10 times, record the initial weight (retain four significant digits), and then install it on the fixture of the reciprocating friction and wear testing machine, set the vertical test force: 1kN, Reciprocating times: 3600 times, time: 3600s, frequency: 1Hz, amplitude: 5mm, lubricated with special oil for aviation bearings, ultrasonic cleaning, drying, weighing and recording the experimental data again after the friction and wear test, the result is 2.632 The wear amount of the sample after the impact of the laser power density of GW/cm ² is 0.00038g, as shown in Figure 4.

Example 4.

Step 1: Prepare 6 pieces of 10mm × 10mm × 10mm samples for heat treatment process. In the heat treatment process, the quenching temperature is 1090 °C, the temperature is kept for 35 minutes, and the third tempering temperature is 540 °C, and the temperature is kept for 2 h. Before each tempering, a cold treatment is required. The cold treatment temperature is -75 °C and the temperature is kept for 2.5 hours. The vacuum degree is 5×10 ^-2 Pa before vacuum air quenching heating.

Step 2: Use 240, 600, 1000, 2000 grit sandpaper to grind the 10mm × 10mm × 10mm block sample after the heat treatment process (vacuum air quenching + tempering) in step 1 to the same roughness, number A1, A2, A3, E1, E2, E3.

Step 3: Group A is not subjected to laser shock treatment. Group E is pasted with a black absorbing layer. The absorbing layer is made of 2100FRTV type black tape (which absorbs energy and prevents laser ablation of the surface of the workpiece), and the absorbing layer needs to be closely attached. Workpiece, no bubbles, impurities, etc.

Step 4: Clamp the sample of group E in the test fixture, set the laser parameters, adjust the water film thickness to 2mm, and use the laser power density of 3.333GW/cm ² to impact the sample on a large area, and the spot overlap ratio The impact path is 50% (9 spots are impacted on one surface), as shown in Figure 1, and the 50% overlap ratio is shown in Figure 2.

Step 5: Move the manipulator to the clamping position, remove the workpiece, remove the absorbing layer, and after micro-polishing 10μm, place the ferrule again in the ultrasonic cleaner to clean for 10min, take it out and blow dry. Test the surface hardness of the unimpacted sample and the sample after impact with different parameters, record the hardness value, and compare the surface hardness of the sample after laser impact. The result is that the surface hardness of the sample after the laser power density of 2.5GW/ ^cm2 is: 745.18HV, as shown in Figure 3.

Step 6: Hold and weigh the samples A and E with tweezers for 10 times, record the initial weight (retain four significant digits), and then install it on the fixture of the reciprocating friction and wear testing machine, set the vertical test force: 1kN, Reciprocating times: 3600 times, time: 3600s, frequency: 1Hz, amplitude: 5mm, using special oil for aviation bearings, after the friction and wear test, ultrasonic cleaning, drying, weighing again, and recording the experimental data, the result is 3.333 The wear amount of the sample after the impact of the laser power density of GW/ ^cm2 is 0.00181g, as shown in Figure 4.

Comparative Example 1.

Step 1: Prepare 6 pieces of 10mm × 10mm × 10mm samples for heat treatment process. In the heat treatment process, the quenching temperature is 1090 °C, the temperature is kept for 35 minutes, and the third tempering temperature is 540 °C, and the temperature is kept for 2 h. Before each tempering, a cold treatment is required. The cold treatment temperature is -75 °C and the temperature is kept for 2.5 hours. The vacuum degree is 5×10 ^-2 Pa before vacuum air quenching heating.

Step 2: Use 240, 600, 1000, 2000 grit sandpaper to grind the 10mm × 10mm × 10mm block samples after the heat treatment process (vacuum air quenching + tempering) in step 1 to the same roughness, numbering A1, A2, A3, B1, B2, B2.

Step 3: Group A is not subjected to laser shock treatment. Group B is pasted with a black absorbing layer. The absorbing layer is made of 2100FRTV black tape (the function of absorbing energy and preventing laser ablation on the surface of the workpiece), and the absorbing layer needs to be closely attached to the workpiece. , No bubbles, no impurities, etc.

Step 4: Clamp the sample of group B in the test fixture, set the laser parameters, adjust the thickness of the water film to 2mm, and use the laser power density of 1.1904GW/ ^cm2 to impact the sample in a large area, and the spot overlap rate is 50% (9 light spots impacted on one surface) impact path, as shown in Figure 1, and 50% overlap ratio, as shown in Figure 2.

Step 5: Move the manipulator to the clamping position, remove the workpiece, remove the absorbing layer, and after micro-polishing 10μm, place the ferrule again in the ultrasonic cleaner to clean for 10min, take it out and blow dry. Test the surface hardness of the unimpacted sample and the sample after impact with different parameters, record the hardness value, and compare the surface hardness of the sample after laser impact. The hardness of the unimpacted sample is 728.18HV, and the laser power density of 1.1904GW/ ^cm2 The surface hardness of the sample is 728.3HV, as shown in Figure 5.

Step 6: Hold and weigh the sample described in Step 5 with tweezers 10 times, record the initial weight (retain four significant digits) and install it on the fixture of the reciprocating friction and wear testing machine, set the vertical test force: 1kN, reciprocating Times: 3600 times, time: 3600s, frequency: 1Hz, amplitude: 5mm, lubricated with special oil for aviation bearings, ultrasonic cleaning, drying, weighing again after the friction and wear test, and recording the experimental data again, no impact sample wear The amount of wear is 0.00595g, and the wear amount of the large-area impact sample with a laser power density of 1.1904GW/cm ² is 0.00233g, as shown in Figure 6.

Comparative Example 2.

Step 1: Prepare 6 pieces of 10mm × 10mm × 10mm samples for heat treatment process. In the heat treatment process, the quenching temperature is 1090 °C, the temperature is kept for 35 minutes, and the third tempering temperature is 540 °C, and the temperature is kept for 2 h. Before each tempering, a cold treatment is required. The cold treatment temperature is -75 °C and the temperature is kept for 2.5 hours. The vacuum degree is 5×10 ^-2 Pa before vacuum air quenching heating.

Step 2: Use 240, 600, 1000, 2000 grit sandpaper to grind the 10mm × 10mm × 10mm block samples after the heat treatment process (vacuum air quenching + tempering) in step 1 to the same roughness, numbering A1, A2, A3, B1, B2, B2.

Step 3: Group A is not subjected to laser shock treatment. Group B is pasted with a black absorbing layer. The absorbing layer is made of 2100FRTV black tape (the function of absorbing energy and preventing laser ablation on the surface of the workpiece), and the absorbing layer needs to be closely attached to the workpiece. , No bubbles, no impurities, etc.

Step 4: Clamp the sample of group B in the test fixture, set the laser parameters, adjust the thickness of the water film to 2mm, and use the laser power density of 3.417GW/ ^cm2 to impact the sample in a large area, and the spot overlap rate is 50% (9 light spots impacted on one surface) impact path, as shown in Figure 1, and 50% overlap ratio, as shown in Figure 2.

Step 5: Move the manipulator to the clamping position, remove the workpiece, remove the absorbing layer, and after micro-polishing 10μm, place the ferrule again in the ultrasonic cleaner to clean for 10min, take it out and blow dry. Test the surface hardness of the unimpacted sample and the sample after impact with different parameters, record the hardness value, and compare the surface hardness of the sample after laser shock. The hardness of the unimpacted sample is 728.18HV, and the laser power density of 3.417GW/ ^cm2 The surface hardness of the sample is 746.9HV, as shown in Figure 5.

Step 6: Hold and weigh the sample described in Step 5 with tweezers 10 times, record the initial weight (retain four significant digits) and install it on the fixture of the reciprocating friction and wear testing machine, set the vertical test force: 1kN, reciprocating Times: 3600 times, time: 3600s, frequency: 1Hz, amplitude: 5mm, lubricated with special oil for aviation bearings, ultrasonic cleaning, drying, weighing again after the friction and wear test, and recording the experimental data again, no impact sample wear The amount of wear is 0.00595g, and the wear amount of the large-area impact sample with a laser power density of 3.417GW/cm ² is 0.00258g, as shown in Figure 6.

Comparative Example 3.

Step 1: Prepare 6 pieces of 10mm × 10mm × 10mm samples for heat treatment process. In the heat treatment process, the quenching temperature is 1090 °C, the temperature is kept for 35 minutes, and the third tempering temperature is 540 °C, and the temperature is kept for 2 h. Before each tempering, a cold treatment is required. The cold treatment temperature is -75 °C and the temperature is kept for 2.5 hours. The vacuum degree is 5×10 ^-2 Pa before vacuum air quenching heating.

Step 2: Use 240, 600, 1000, 2000 grit sandpaper to grind the 10mm × 10mm × 10mm block samples after the heat treatment process (vacuum air quenching + tempering) in step 1 to the same roughness, numbering A1, A2, A3, B1, B2, B2.

Step 3: Group A is not subjected to laser shock treatment. Group B is pasted with a black absorbing layer. The absorbing layer is made of 2100FRTV black tape (the function of absorbing energy and preventing laser ablation on the surface of the workpiece), and the absorbing layer needs to be closely attached to the workpiece. , No bubbles, no impurities, etc.

Step 4: Clamp the sample of group B in the test fixture, set the laser parameters, adjust the water film thickness to 2mm, and use the laser power density of 1.974GW/ ^cm2 to impact the sample in a large area, and the spot overlap rate is 30% (9 light spots impacted on one surface) impact path, as shown in Figure 1.

Step 5: Move the manipulator to the clamping position, remove the workpiece, remove the absorbing layer, and after micro-polishing 10μm, place the ferrule again in the ultrasonic cleaner to clean for 10min, take it out and blow dry. Test the surface hardness of the unimpacted sample and the sample after impact with different parameters, record the hardness value, and compare the surface hardness of the sample after laser shock. The hardness of the unimpacted sample is 728.18HV, and the laser power density of 1.974GW/ ^cm2 The surface hardness distribution of the samples is uneven, which are 728.9 and 730.88HV, respectively.

Step 6: Hold and weigh the sample described in Step 5 with tweezers 10 times, record the initial weight (retain four significant digits) and install it on the fixture of the reciprocating friction and wear testing machine, set the vertical test force: 1kN, reciprocating Times: 3600 times, time: 3600s, frequency: 1Hz, amplitude: 5mm, lubricated with special oil for aviation bearings, ultrasonic cleaning, drying, weighing again after the friction and wear test, and recording the experimental data again, no impact sample wear The amount of wear is 0.00595g, and the wear amount of the large-area impact sample with a laser power density of 1.974GW/cm ² is 0.00183g, as shown in Figure 7.

Comparative Example 4.

Step 1: Prepare 6 pieces of 10mm × 10mm × 10mm samples for heat treatment process. In the heat treatment process, the quenching temperature is 1090 °C, the temperature is kept for 35 minutes, and the third tempering temperature is 540 °C, and the temperature is kept for 2 h. Before each tempering, a cold treatment is required. The cold treatment temperature is -75 °C and the temperature is kept for 2.5 hours. The vacuum degree is 5×10 ^-2 Pa before vacuum air quenching heating.

Step 2: Use 240, 600, 1000, 2000 grit sandpaper to grind the 10mm × 10mm × 10mm block samples after the heat treatment process (vacuum air quenching + tempering) in step 1 to the same roughness, numbering A1, A2, A3, B1, B2, B2.

Step 3: Group A is not subjected to laser shock treatment. Group B is pasted with a black absorbing layer. The absorbing layer is made of 2100FRTV black tape (the function of absorbing energy and preventing laser ablation on the surface of the workpiece), and the absorbing layer needs to be closely attached to the workpiece. , No bubbles, no impurities, etc.

Step 4: Clamp the sample of group B in the test fixture, set the laser parameters, adjust the water film thickness to 2mm, and use the laser power density of 1.974GW/ ^cm2 to impact the sample in a large area, and the spot overlap rate is 80% (9 light spots impacted on one surface) impact path, as shown in Figure 1.

Step 5: Move the manipulator to the clamping position, remove the workpiece, remove the absorbing layer, and after micro-polishing 10μm, place the ferrule again in the ultrasonic cleaner to clean for 10min, take it out and blow dry. Test the surface hardness of the unimpacted sample and the sample after impact with different parameters, record the hardness value, and compare the surface hardness of the sample after laser shock. The hardness of the unimpacted sample is 728.18HV, and the laser power density of 1.974GW/ ^cm2 The surface hardness of the sample is 731.2HV and 733.8HV, and the surface hardness distribution is uneven.

Step 6: Hold and weigh the sample described in Step 5 with tweezers 10 times, record the initial weight (retain four significant digits) and install it on the fixture of the reciprocating friction and wear testing machine, set the vertical test force: 1kN, reciprocating Times: 3600 times, time: 3600s, frequency: 1Hz, amplitude: 5mm, lubricated with special oil for aviation bearings, ultrasonic cleaning, drying, weighing again after the friction and wear test, and recording the experimental data again, no impact sample wear The amount of wear is 0.00595g, and the wear amount of the large-area impact sample with a laser power density of 1.974GW/cm ² is 0.00156g, as shown in Figure 7.

The above descriptions are merely embodiments of the present invention, and are not intended to limit the protection scope of the present invention. Any modification, equivalent replacement, improvement, expansion, etc. made within the spirit and principle of the present invention are included in the protection scope of the present invention.

Claims (5)

1. a process method utilizing laser shock to improve G13Cr4Mo4Ni4V steel surface hardness and wear resistance, is characterized in that, comprises the steps: Step 1: The heat treatment process of vacuum air quenching + tempering is performed on the sample; Step 2: Grind the 10mm×10mm×10mm block sample after the heat treatment process described in step 1 to the same roughness; Step 3: Paste the black absorbing layer on the sample; Step 4: Clamp the sample on the special test fixture for laser shock strengthening treatment; Step 5: Measure the surface hardness and wear resistance of the samples after laser shock treatment. 2. The process method for improving the surface hardness and wear resistance of G13Cr4Mo4Ni4V steel according to claim 1, characterized in that, in the step 1, the quenching temperature in the heat treatment process is 1070-1090 ℃, and the heat preservation is 30 ℃. ~35min, the three tempering temperature is 540℃-560℃, and the heat preservation is 1.5-3.5 h. Before each tempering, a cold treatment is required. The cold treatment temperature is -75℃~-65℃, and the heat preservation is 2h~3h; vacuum quenching heating The front vacuum degree is lower than 5×10 ^-2 Pa. 3. a kind of processing method utilizing laser shock to improve G13Cr4Mo4Ni4V steel surface hardness and wear resistance according to claim 1, is characterized in that, in described step 3, absorption layer adopts model and is 2100FRTV type black tape, black paint or For any one of the aluminum foils, the absorbing layer is required to be closely attached to the workpiece, free of air bubbles, impurities, etc. 4. a kind of processing method that utilizes laser shock strengthening to improve G13Cr4Mo4Ni4V steel surface hardness and wear resistance according to claim 1, is characterized in that, in described step 4, with 1.974GW/cm ² -3.333GW/cm ² The laser power density is high to impact the surface of the sample in a large area, and the thickness of the water film is 1-2mm. 5. a kind of processing method utilizing laser shock to improve surface hardness and wear resistance of G13Cr4Mo4Ni4V steel according to claim 1, is characterized in that, in described step 4, laser energy distribution adopts flat-top distribution, and light spot is 4mm × 4mm square Light spot, the light spot adopts 50%-75% overlap rate.

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