CN114959247A - Laser shock peening method for prolonging fatigue life of stabilized 8Cr4Mo4V aviation bearing steel - Google Patents
Laser shock peening method for prolonging fatigue life of stabilized 8Cr4Mo4V aviation bearing steel Download PDFInfo
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- CN114959247A CN114959247A CN202210708773.XA CN202210708773A CN114959247A CN 114959247 A CN114959247 A CN 114959247A CN 202210708773 A CN202210708773 A CN 202210708773A CN 114959247 A CN114959247 A CN 114959247A
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- 230000035939 shock Effects 0.000 title claims abstract description 116
- 229910000831 Steel Inorganic materials 0.000 title claims abstract description 94
- 239000010959 steel Substances 0.000 title claims abstract description 94
- 238000000034 method Methods 0.000 title claims abstract description 45
- 238000005728 strengthening Methods 0.000 claims abstract description 71
- 238000011282 treatment Methods 0.000 claims abstract description 55
- 238000010438 heat treatment Methods 0.000 claims abstract description 31
- 238000000227 grinding Methods 0.000 claims abstract description 22
- 238000010791 quenching Methods 0.000 claims abstract description 17
- 230000000171 quenching effect Effects 0.000 claims abstract description 17
- 238000005496 tempering Methods 0.000 claims abstract description 12
- 238000010521 absorption reaction Methods 0.000 claims description 25
- 238000004140 cleaning Methods 0.000 claims description 25
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 claims description 18
- 239000011241 protective layer Substances 0.000 claims description 18
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 16
- 239000010410 layer Substances 0.000 claims description 11
- 230000006641 stabilisation Effects 0.000 claims description 11
- 238000011105 stabilization Methods 0.000 claims description 11
- 239000002390 adhesive tape Substances 0.000 claims description 9
- 238000001035 drying Methods 0.000 claims description 9
- 238000004321 preservation Methods 0.000 claims description 8
- 238000004506 ultrasonic cleaning Methods 0.000 claims description 8
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 claims description 3
- 229910052782 aluminium Inorganic materials 0.000 claims description 3
- 239000011888 foil Substances 0.000 claims description 3
- 239000003973 paint Substances 0.000 claims description 3
- 230000000087 stabilizing effect Effects 0.000 abstract description 18
- 230000002035 prolonged effect Effects 0.000 abstract description 3
- 238000005452 bending Methods 0.000 description 124
- 239000012535 impurity Substances 0.000 description 21
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 14
- 238000012360 testing method Methods 0.000 description 13
- 239000007789 gas Substances 0.000 description 12
- 238000002679 ablation Methods 0.000 description 9
- 238000005498 polishing Methods 0.000 description 8
- 238000004381 surface treatment Methods 0.000 description 8
- 239000000084 colloidal system Substances 0.000 description 7
- 239000000428 dust Substances 0.000 description 7
- 229910052757 nitrogen Inorganic materials 0.000 description 7
- 238000007664 blowing Methods 0.000 description 6
- 230000003313 weakening effect Effects 0.000 description 6
- 238000010586 diagram Methods 0.000 description 5
- 239000000463 material Substances 0.000 description 5
- 238000009661 fatigue test Methods 0.000 description 4
- 230000000052 comparative effect Effects 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- 244000137852 Petrea volubilis Species 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000007797 corrosion Effects 0.000 description 1
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- 230000002028 premature Effects 0.000 description 1
- 238000005096 rolling process Methods 0.000 description 1
- 238000005480 shot peening Methods 0.000 description 1
- 239000002344 surface layer Substances 0.000 description 1
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D10/00—Modifying the physical properties by methods other than heat treatment or deformation
- C21D10/005—Modifying the physical properties by methods other than heat treatment or deformation by laser shock processing
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
- C21D1/18—Hardening; Quenching with or without subsequent tempering
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
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- C21D6/04—Hardening by cooling below 0 degrees Celsius
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- C—CHEMISTRY; METALLURGY
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- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
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Abstract
The invention relates to a laser shock strengthening method for prolonging the fatigue life of stabilized 8Cr4Mo4V aviation bearing steel. According to the invention, residual compressive stress can be formed on the surface of the 8Cr4Mo4V aviation bearing steel through the steps of quenching and tempering heat treatment, tertiary stabilizing treatment, coarse grinding and laser impact on the 8Cr4Mo4V aviation bearing steel, so that the fatigue life of the 8Cr4Mo4V steel is effectively prolonged.
Description
Technical Field
The invention belongs to the field of laser shock peening processing, and relates to a laser shock peening method for prolonging the fatigue life of stabilized 8Cr4Mo4V aviation bearing steel.
Background
The 8Cr4Mo4V bearing steel has a plurality of strengthening methods, but the laser shock peening is a novel strengthening method, and compared with the traditional shot peening strengthening and rolling strengthening, the laser shock peening has the advantages that the laser shock peening is not in direct contact with materials, a heat affected zone is not formed, the damage to a test piece is small, the controllability is high, and the like.
The 8Cr4Mo4V steel is mainly used for manufacturing aviation bearings, and the aviation bearings have high requirements on the comprehensive mechanical properties of the surface of parts, such as hardness, wear resistance, corrosion resistance and the like, so that the improvement of the comprehensive mechanical properties and the fatigue life of the bearing steel are also strengthening targets. Experiments show that laser shock peening can cause the surface layer of the material to generate plastic deformation and has a residual compressive stress layer with a certain depth, so that the comprehensive mechanical property of the material is improved, and the fatigue life of the material is prolonged.
Disclosure of Invention
In view of the above problems, the present invention aims to provide a laser shock peening method for improving the fatigue life of stabilized 8Cr4Mo4V aviation bearing steel. The comprehensive mechanical property and the fatigue life of the 8Cr4Mo4V aviation bearing steel treated by the method are greatly improved.
In order to solve the above technical problems, the present invention specifically provides the following technical solutions.
A laser shock strengthening method for prolonging the fatigue life of 8Cr4Mo4V aviation bearing steel after stabilization treatment comprises the following steps:
the method comprises the following steps: carrying out quenching and tempering heat treatment on the 8Cr4Mo4V aviation bearing steel part;
step two: carrying out stabilization treatment on 8Cr4Mo4V aviation bearing steel parts for three times;
step three: removing an oxide layer on the surface of the 8Cr4Mo4V aviation bearing steel part due to heat treatment in a coarse grinding mode;
step four: cleaning the surface of the 8Cr4Mo4V aviation bearing steel part by using an ultrasonic cleaner and absolute ethyl alcohol, and attaching an absorption protective layer to an area of the 8Cr4Mo4V aviation bearing steel part, which needs to be subjected to laser shock strengthening;
step five: clamping the 8Cr4Mo4V aviation bearing steel part on a manipulator, moving the manipulator to enable laser square spots to fall on an area, needing laser shock strengthening, on the surface of the 8Cr4Mo4V aviation bearing steel part, adjusting a water channel to enable the surface of the 8Cr4Mo4V aviation bearing steel part needing laser shock strengthening to be covered with a 1-2mm water film, and then carrying out laser shock on the surface of the 8Cr4Mo4V aviation bearing steel part;
step six: after the laser shock strengthening is finished, taking down the 8Cr4Mo4V aviation bearing steel part, then putting the part into an ultrasonic cleaning machine, cleaning the part by using absolute ethyl alcohol, and drying the part by using cold air for later use;
step seven: the 8Cr4Mo4V aviation bearing steel parts are ground and polished by using grinding sandpaper with the granularity of 600, 1000, 2000, 5000 and 6000 respectively.
Further, in the first step, the vacuum quenching treatment condition is 1080-1100 ℃, the heat preservation time is 22-42min, the temperature of the third tempering treatment is 540-560 ℃, and the heat preservation time is 1.5-3.5 h.
Further, in the second step, the stabilizing treatment conditions are that the cold treatment temperature is minus 80 ℃ to minus 60 ℃, the heat preservation time is 1.5 to 3.5 hours, the heat treatment temperature is 430 ℃ to 500 ℃, and the heat preservation time is 1.5 to 3.5 hours. The primary cold treatment and the primary heat treatment are primary stabilization treatments.
Further, the absorption protective layer in the fourth step is any one of a black adhesive tape, black paint or an aluminum foil.
Further, in the fifth step, the pulse width of the laser shock peening parameter selection range is 15Ns-21Ns, the laser output power is 3J-8J, the side length of a laser square spot is 3.5mm-4.5mm, and the lap joint rate of the square spot is 25% -50%.
Further, in the seventh step, the bearing steel with surface damage after laser shock peening is subjected to surface damage grinding treatment, wherein the grinding amount of the bearing steel is 10-30 μm.
Compared with the prior art, the invention has the beneficial effects that.
1. The heat treatment process and the three times of stabilizing treatment of the 8Cr4Mo4V aircraft bearing steel part are added before the laser shock strengthening is carried out on the 8Cr4Mo4V aircraft bearing steel part, so that the residual stress in the bearing steel part can be better eliminated, the service time of the part is prolonged, and a better strengthening effect is obtained.
2. The method has the advantages that more efficient laser shock strengthening parameters are selected for strengthening 8Cr4Mo4V aviation bearing steel parts in a targeted manner, different laser shock strengthening parameters have different strengthening effects on different materials, for 8Cr4Mo4V aviation bearing steel, the optimal laser shock strengthening parameters for the 8Cr4Mo4V aviation bearing steel are selected, so that the best strengthening effect is achieved, and the structure and the mechanical property of the 8Cr4Mo4V aviation bearing steel are improved to the greatest extent.
3. After the laser shock strengthening is carried out on the 8Cr4Mo4V aviation bearing steel part, and aiming at the situation that the laser shock strengthening generates ablation on the 8Cr4Mo4V aviation bearing steel part, whatever laser shock strengthening parameters generate a certain degree of ablation on the surface of the 8Cr4Mo4V aviation bearing steel part, the roughness of the surface of the 8Cr4Mo4V aviation bearing steel part is increased due to the ablation, the crack propagation on the surface of the 8Cr4Mo4V aviation bearing steel part can be accelerated, the fatigue life of the 8Cr4Mo4V aviation bearing steel part is reduced, the surface treatment process of the 8Cr4Mo4V aviation bearing steel part is increased, and the condition that the fatigue failure of a test piece occurs in advance due to the crack propagation caused by the surface ablation of the 8Cr4Mo4V aviation bearing steel part is prevented.
4. Through fatigue test results, the strengthening method provided by the invention can effectively improve the comprehensive mechanical property of the 8Cr4Mo4V aviation bearing steel part and prolong the fatigue life of the 8Cr4Mo4V aviation bearing steel part.
Drawings
FIG. 1 is a schematic drawing showing the dimensions of an 8Cr4Mo4V bending element used in the present invention.
FIG. 2 is a schematic diagram of the laser shock peening region of an 8Cr4Mo4V rotor according to the present invention.
FIG. 3 is a surface state of a test piece under a light mirror before laser shock peening in example 1.
FIG. 4 is a surface state of a test piece under an electron microscope before laser shock peening in example 1.
FIG. 5 is a surface state of a test piece under a light mirror after laser shock peening in example 1.
FIG. 6 is a surface state of a test piece under an electron microscope after laser shock peening in example 1.
FIG. 7 shows the surface hardness and fatigue strength changes of the test pieces of examples 1 to 3 after laser shock peening with different output powers.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described in detail with reference to the following embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
A laser shock strengthening method for prolonging the fatigue life of 8Cr4Mo4V aviation bearing steel after stabilization treatment comprises the following steps:
the method comprises the following steps: placing the 8Cr4Mo4V aviation bearing steel parts in a vacuum furnace in sequence, setting a heat treatment process route of vacuum gas quenching, raising the temperature in the vacuum furnace to 1080-1100 ℃, preserving heat for 22-42min, then filling 2bar of nitrogen into the vacuum furnace, and then tempering the 8Cr4Mo4V aviation bearing steel parts for three times at 540-560 ℃ for 1.5-3.5 h.
Step two: and (3) carrying out three times of stabilizing treatment on the heat-treated 8Cr4Mo4V aviation bearing steel part, wherein each time of stabilizing treatment is respectively one time of cold treatment and one time of heat treatment, the temperature of the cold treatment is minus 80 ℃ to minus 60 ℃, the heat preservation time is 1.5-3.5h, and the temperature of the heat treatment is 430 ℃ to 500 ℃, and the heat preservation time is 1.5-3.5 h.
Step three: and (3) carrying out surface grinding and polishing treatment on the 8Cr4Mo4V aviation bearing steel part subjected to heat treatment and three times of stabilizing treatment, and removing an oxidation layer generated on the surface of the 8Cr4Mo4V aviation bearing steel part due to heat treatment.
Step four: cleaning impurities on the surface of the 8Cr4Mo4V aviation bearing steel part by using an ultrasonic cleaner and absolute ethyl alcohol, drying the part by using a blower with cold air, uniformly pasting a black adhesive tape, an aluminum foil or a black paint on the area to be subjected to laser shock strengthening on the surface of the 8Cr4Mo4V aviation bearing steel part as an absorption protective layer, wherein the absorption protective layer is tightly attached to the surface of the 8Cr4Mo4V aviation bearing steel part, and bubbles, dust, impurities and the like cannot appear.
Step five: fixing the 8Cr4Mo4V aviation bearing steel part on a manipulator by using a clamp, moving the manipulator to enable a laser square spot to fall on an area needing laser shock strengthening on the surface of the 8Cr4Mo4V aviation bearing steel part, adjusting a water path to enable the surface of the 8Cr4Mo4V aviation bearing steel part needing laser shock strengthening to be covered with a 1-2mm water film, then carrying out laser shock on the 8Cr4Mo4V aviation bearing steel part, selecting the output energy of a laser to be 3J-8J, the laser pulse width to be 15Ns-21Ns, the side length of the laser square spot to be 3.5-4.5 mm, and controlling the lap-joint rate to be 25-50%.
Step six: the method comprises the steps of taking down the laser shock strengthened 8Cr4Mo4V aviation bearing steel part, removing an absorption layer on the surface of the 8Cr4Mo4V aviation bearing steel part, cleaning the 8Cr4Mo4V aviation bearing steel part by using absolute ethyl alcohol, removing colloid on the surface due to high temperature, and cleaning the 8Cr4Mo4V aviation bearing steel part by using an ultrasonic cleaner to remove impurities on the 8Cr4Mo4V aviation bearing steel part.
Step seven: fixing the 8Cr4Mo4V aviation bearing steel part, and grinding and polishing the 8Cr4Mo4V aviation bearing steel part by using sand paper with the grain size of 600 #, 1000 #, 2000 # and 5000#, wherein the grinding amount is 10-30 mu m, so as to eliminate the crack propagation caused by ablation on the surface of the 8Cr4Mo4V aviation bearing steel part due to laser shock strengthening and further cause premature fatigue failure of the 8Cr4Mo4V aviation bearing steel part.
Example 1.
A laser shock strengthening method for prolonging the fatigue life of 8Cr4Mo4V aviation bearing steel after stabilization treatment comprises the following steps:
the method comprises the following steps: putting the 8Cr4Mo4V rotary bending piece into a vacuum furnace, setting a heat treatment process route of vacuum gas quenching, raising the temperature in the vacuum furnace to 1090 ℃ and preserving the temperature for 32min, then filling 2bar of nitrogen into the vacuum furnace, and then carrying out tempering treatment on the rotary bending piece for 2.5h at 550 ℃ for three times, wherein the size of the used 8Cr4Mo4V rotary bending piece is shown in figure 1.
Step two: and (3) carrying out three times of stabilizing treatment on the 8Cr4Mo4V rotary bending piece after the heat treatment, wherein each time of stabilizing treatment is respectively one time of cold treatment and one time of heat treatment, the temperature of the cold treatment is kept at-70 ℃ for 2.5h, and the temperature of the heat treatment is kept at 440 ℃ for 2.5 h.
Step three: the 8Cr4Mo4V rotary bending piece subjected to vacuum gas quenching and three times of stabilizing treatment is subjected to surface treatment of grinding and polishing to remove oxides on the surface of the 8Cr4Mo4V rotary bending piece, so that the 8Cr4Mo4V rotary bending piece can be subjected to next laser shock strengthening conveniently, the weakening influence of the oxides on the laser shock strengthening degree is eliminated, and after the 8Cr4Mo4V rotary bending piece is subjected to surface treatment, the surface states under a light mirror and an electron microscope before laser shock strengthening are shown in fig. 3 and 4.
Step four: cleaning impurities on the surface of the 8Cr4Mo4V rotary bending piece by using an ultrasonic cleaner and absolute ethyl alcohol, drying the part by blowing cold air by using a blower, uniformly pasting a black adhesive tape on an area to be subjected to laser shock strengthening on the surface of the 8Cr4Mo4V rotary bending piece to be used as an absorption protective layer, wherein the absorption protective layer is tightly pasted with the surface of the 8Cr4Mo4V rotary bending piece, and air bubbles, dust, impurities and the like cannot appear.
Step five: fixing the 8Cr4Mo4V rotary bending piece on a manipulator by using a clamp, moving the manipulator to enable a laser square spot to fall on an area needing laser shock strengthening on the surface of the 8Cr4Mo4V rotary bending piece, wherein a schematic diagram of the area needing laser shock strengthening is shown in figure 2, then adjusting a water path to enable the surface of the 8Cr4Mo4V rotary bending piece needing laser shock strengthening to be covered with a water film with the thickness of 1mm, then carrying out laser shock on the 8Cr4Mo4V rotary bending piece, selecting the output energy of a laser to be 8J, the laser pulse width to be 15Ns, the side length of a laser square spot to be 4mm, and controlling the lap ratio to be 30%. Fig. 5 and 6 show the surface states of the 8Cr4Mo4V spiral bend after laser shock peening under a mirror and an electron microscope, respectively.
Step six: and taking down the 8Cr4Mo4V rotary bending piece subjected to laser shock strengthening, removing an absorption layer on the surface of the 8Cr4Mo4V rotary bending piece, cleaning the 8Cr4Mo4V rotary bending piece by using absolute ethyl alcohol, removing colloid on the surface due to high temperature, and cleaning impurities on the 8Cr4Mo4V rotary bending piece by using an ultrasonic cleaning machine.
Step seven: the 8Cr4Mo4V rotary bending piece is fixed, and the 8Cr4Mo4V rotary bending piece is ground and polished by sandpaper with the grain sizes of 600 #, 1000 #, 2000 # and 5000#, wherein the grinding amount is 20 mu m, so that the problem that the 8Cr4Mo4V rotary bending piece is fatigue failure in advance due to crack propagation caused by ablation on the surface of the 8Cr4Mo4V rotary bending piece due to laser shock strengthening is solved.
Step eight: the 8Cr4Mo4V spin-bent piece was placed in a fatigue life testing machine for fatigue testing to verify the improvement in fatigue life of the 8Cr4Mo4V spin-bent piece by laser shock peening, and the improvement in hardness and fatigue life of the 8Cr4Mo4V spin-bent piece after laser shock peening is shown in fig. 7.
Example 2.
A laser shock strengthening method for prolonging the fatigue life of 8Cr4Mo4V aviation bearing steel after stabilization treatment comprises the following steps:
the method comprises the following steps: putting the 8Cr4Mo4V rotary bending piece into a vacuum furnace, setting a heat treatment process route of vacuum gas quenching, raising the temperature in the vacuum furnace to 1090 ℃ and preserving the temperature for 32min, then filling 2bar of nitrogen into the vacuum furnace, and then carrying out tempering treatment on the rotary bending piece for 2.5h at 550 ℃ for three times, wherein the size of the used 8Cr4Mo4V rotary bending piece is shown in figure 1.
Step two: and carrying out three times of stabilizing treatment on the thermally treated rotary bending piece, wherein each time of stabilizing treatment is respectively one time of cold treatment and one time of heat treatment, the temperature of the cold treatment is-70 ℃, the temperature is kept for 2.5h, and the temperature of the heat treatment is 440 ℃, the temperature is kept for 2.5 h.
Step three: the 8Cr4Mo4V rotary bending piece which is subjected to vacuum gas quenching and three times of stabilizing treatment is subjected to surface treatment of grinding and polishing to remove oxides on the surface of the 8Cr4Mo4V rotary bending piece, so that the 8Cr4Mo4V rotary bending piece is conveniently subjected to next step of laser shock peening, and the weakening influence of the oxides on the laser shock peening degree is eliminated.
Step four: cleaning impurities on the surface of the 8Cr4Mo4V rotary bending piece by using an ultrasonic cleaner and absolute ethyl alcohol, drying the part by blowing cold air by using a blower, and uniformly pasting a black adhesive tape absorption protective layer on an area to be subjected to laser shock strengthening on the surface of the 8Cr4Mo4V rotary bending piece, wherein the absorption protective layer is tightly pasted with the surface of the 8Cr4Mo4V rotary bending piece, and bubbles, dust, impurities and the like cannot appear.
Step five: fixing the 8Cr4Mo4V rotary bending piece on a manipulator by using a clamp, moving the manipulator to enable a laser square spot to fall on an area, needing laser shock strengthening, on the surface of the 8Cr4Mo4V rotary bending piece, wherein a schematic diagram of the area needing shock strengthening is shown in figure 2, then adjusting a water path to enable the surface of the 8Cr4Mo4V rotary bending piece needing laser shock strengthening to be covered with a water film with the thickness of 1mm, then carrying out laser shock on the 8Cr4Mo4V rotary bending piece, selecting the output energy of a laser to be 4J, the laser pulse width to be 15Ns, the laser square spot side length to be 4mm, and controlling the lapping rate to be 30%.
Step six: and taking down the 8Cr4Mo4V rotary bending piece subjected to laser shock strengthening, removing an absorption layer on the surface of the 8Cr4Mo4V rotary bending piece, cleaning the 8Cr4Mo4V rotary bending piece by using absolute ethyl alcohol, removing colloid on the surface due to high temperature, and cleaning impurities on the 8Cr4Mo4V rotary bending piece by using an ultrasonic cleaning machine.
Step seven: the 8Cr4Mo4V rotary bending piece is fixed, and the 8Cr4Mo4V rotary bending piece is ground and polished by sandpaper with the grain sizes of 600 #, 1000 #, 2000 # and 5000#, wherein the grinding amount is 20 mu m, so that the problem that the 8Cr4Mo4V rotary bending piece is fatigue failure in advance due to crack propagation caused by ablation on the surface of the 8Cr4Mo4V rotary bending piece due to laser shock strengthening is solved.
Step eight: the 8Cr4Mo4V spin-bent piece was placed in a fatigue life testing machine for fatigue testing to verify the improvement in fatigue life of the 8Cr4Mo4V spin-bent piece by laser shock peening, and the improvement in hardness and fatigue life of the 8Cr4Mo4V spin-bent piece after laser shock peening is shown in fig. 7.
Example 3.
A laser shock strengthening method for prolonging the fatigue life of 8Cr4Mo4V aviation bearing steel after stabilization treatment comprises the following steps:
the method comprises the following steps: putting the 8Cr4Mo4V rotary bending piece into a vacuum furnace, setting a heat treatment process route of vacuum gas quenching, raising the temperature in the vacuum furnace to 1090 ℃ and preserving the temperature for 32min, then filling 2bar of nitrogen into the vacuum furnace, and then carrying out tempering treatment on the rotary bending piece for 2.5h at 550 ℃ for three times, wherein the size of the used 8Cr4Mo4V rotary bending piece is shown in figure 1.
Step two: and carrying out three times of stabilizing treatment on the thermally treated rotary bending piece, wherein each time of stabilizing treatment is respectively one time of cold treatment and one time of heat treatment, the temperature of the cold treatment is-70 ℃, the temperature is kept for 2.5h, and the temperature of the heat treatment is 440 ℃, the temperature is kept for 2.5 h.
Step three: the 8Cr4Mo4V rotary bending piece which is subjected to vacuum gas quenching and three times of stabilizing treatment is subjected to surface treatment of grinding and polishing to remove oxides on the surface of the 8Cr4Mo4V rotary bending piece, so that the 8Cr4Mo4V rotary bending piece is conveniently subjected to next step of laser shock peening, and the weakening influence of the oxides on the laser shock peening degree is eliminated.
Step four: cleaning impurities on the surface of the 8Cr4Mo4V rotary bending piece by using an ultrasonic cleaner and absolute ethyl alcohol, drying the part by blowing cold air by using a blower, and uniformly pasting a black adhesive tape absorption protective layer on an area to be subjected to laser shock strengthening on the surface of the 8Cr4Mo4V rotary bending piece, wherein the absorption protective layer is tightly pasted with the surface of the 8Cr4Mo4V rotary bending piece, and bubbles, dust, impurities and the like cannot appear.
Step five: fixing the 8Cr4Mo4V rotary bending piece on a manipulator by using a clamp, moving the manipulator to enable a laser square spot to fall on an area needing laser shock strengthening on the surface of the 8Cr4Mo4V rotary bending piece, wherein a schematic diagram of the area needing laser shock strengthening is shown in figure 2, then adjusting a water path to enable the surface of the 8Cr4Mo4V rotary bending piece needing laser shock strengthening to be covered with a water film with the thickness of 1mm, then carrying out laser shock on the 8Cr4Mo4V rotary bending piece, selecting the output energy of a laser to be 6J, the laser pulse width to be 15Ns, the side length of a laser square spot to be 4mm, and controlling the lap ratio to be 30%.
Step six: and taking down the 8Cr4Mo4V rotary bending piece subjected to laser shock strengthening, removing an absorption layer on the surface of the 8Cr4Mo4V rotary bending piece, cleaning the 8Cr4Mo4V rotary bending piece by using absolute ethyl alcohol, removing colloid on the surface due to high temperature, and cleaning impurities on the 8Cr4Mo4V rotary bending piece by using an ultrasonic cleaning machine.
Step seven: the 8Cr4Mo4V rotary bending piece is fixed, and the 8Cr4Mo4V rotary bending piece is ground and polished by sandpaper with the grain sizes of 600 #, 1000 #, 2000 # and 5000#, wherein the grinding amount is 20 mu m, so that the problem that the 8Cr4Mo4V rotary bending piece is fatigue failure in advance due to crack propagation caused by ablation on the surface of the 8Cr4Mo4V rotary bending piece due to laser shock strengthening is solved.
Step eight: the 8Cr4Mo4V spin-bent piece was placed in a fatigue life testing machine for fatigue testing to verify the improvement of the fatigue life of the 8Cr4Mo4V spin-bent piece by laser shock peening, and the improvement of the hardness and fatigue life of the 8Cr4Mo4V spin-bent piece after laser shock peening is shown in fig. 7.
Comparative example 1.
The method comprises the following steps: putting the 8Cr4Mo4V rotary bending piece into a vacuum furnace, setting a heat treatment process route of vacuum gas quenching, raising the temperature in the vacuum furnace to 1090 ℃ and preserving the temperature for 32min, then filling 2bar of nitrogen into the vacuum furnace, and then carrying out tempering treatment on the rotary bending piece for 2.5h at 550 ℃ for three times.
Step two: the 8Cr4Mo4V rotary bending piece is subjected to grinding and polishing surface treatment to remove oxides on the surface of the 8Cr4Mo4V rotary bending piece, so that the 8Cr4Mo4V rotary bending piece is convenient to carry out next laser shock peening, and the weakening influence of the oxides on the laser shock peening degree is eliminated.
Step three: cleaning impurities on the surface of the 8Cr4Mo4V rotary bending piece by using an ultrasonic cleaner and absolute ethyl alcohol, drying the part by blowing cold air by using a blower, and uniformly pasting a black adhesive tape absorption protective layer on an area to be subjected to laser shock strengthening on the surface of the 8Cr4Mo4V rotary bending piece, wherein the absorption protective layer is tightly pasted with the surface of the 8Cr4Mo4V rotary bending piece, and bubbles, dust, impurities and the like cannot appear.
Step four: fixing the 8Cr4Mo4V rotary bending piece on a manipulator by using a clamp, moving the manipulator to enable a laser square spot to fall on an area needing laser shock strengthening on the surface of the 8Cr4Mo4V rotary bending piece, wherein a schematic diagram of the area needing laser shock strengthening is shown in figure 2, then adjusting a water path to enable the surface of the 8Cr4Mo4V rotary bending piece needing laser shock strengthening to be covered with a water film with the thickness of 1mm, then carrying out laser shock on the 8Cr4Mo4V rotary bending piece, selecting the output energy of a laser to be 8J, the laser pulse width to be 15Ns, the side length of a laser square spot to be 4mm, and controlling the lap ratio to be 30%.
Step five: and taking down the 8Cr4Mo4V rotary bending piece subjected to laser shock strengthening, removing an absorption layer on the surface of the 8Cr4Mo4V rotary bending piece, cleaning the 8Cr4Mo4V rotary bending piece by using absolute ethyl alcohol, removing colloid on the surface due to high temperature, and cleaning impurities on the 8Cr4Mo4V rotary bending piece by using an ultrasonic cleaning machine.
Step six: the 8Cr4Mo4V rotary bending piece is fixed, and the 8Cr4Mo4V rotary bending piece is ground and polished by sandpaper with the grain sizes of 600 #, 1000 #, 2000 # and 5000#, wherein the grinding amount is 20 mu m, so that the problem that the 8Cr4Mo4V rotary bending piece is fatigue failure in advance due to crack propagation caused by ablation on the surface of the 8Cr4Mo4V rotary bending piece due to laser shock strengthening is solved.
The hardness and fatigue limit strength of 8Cr4Mo4V bearing steel test pieces were measured to be 822HV1 and 1000MPa respectively by using a Vickers hardness tester and a rotary bending fatigue tester.
Comparative example 2.
The method comprises the following steps: putting the 8Cr4Mo4V rotary bending piece into a vacuum furnace, setting a heat treatment process route of vacuum gas quenching, raising the temperature in the vacuum furnace to 1090 ℃ and preserving the temperature for 32min, then filling 2bar of nitrogen into the vacuum furnace, and then carrying out tempering treatment on the rotary bending piece for 2.5h at 550 ℃ for three times.
Step two: and (3) carrying out three times of stabilizing treatment on the 8Cr4Mo4V rotary bending piece after the heat treatment, wherein each time of stabilizing treatment is respectively one time of cold treatment and one time of heat treatment, the temperature of the cold treatment is kept at-70 ℃ for 2.5h, and the temperature of the heat treatment is kept at 440 ℃ for 2.5 h.
Step three: the 8Cr4Mo4V rotary bending piece which is subjected to vacuum gas quenching and three times of stabilizing treatment is subjected to surface treatment of grinding and polishing to remove oxides on the surface of the 8Cr4Mo4V rotary bending piece, so that the 8Cr4Mo4V rotary bending piece is conveniently subjected to next step of laser shock peening, and the weakening influence of the oxides on the laser shock peening degree is eliminated.
Step four: cleaning impurities on the surface of the 8Cr4Mo4V rotary bending piece by using an ultrasonic cleaner and absolute ethyl alcohol, drying the part by blowing cold air by using a blower, uniformly pasting a black adhesive tape on an area to be subjected to laser shock strengthening on the surface of the 8Cr4Mo4V rotary bending piece to be used as an absorption protective layer, wherein the absorption protective layer is tightly pasted with the surface of the 8Cr4Mo4V rotary bending piece, and air bubbles, dust, impurities and the like cannot appear.
Step five: fixing the 8Cr4Mo4V rotary bending piece on a manipulator by using a clamp, moving the manipulator to enable a laser square spot to fall in an area needing laser shock strengthening on the surface of the 8Cr4Mo4V rotary bending piece, then adjusting a water path to enable the surface of the 8Cr4Mo4V rotary bending piece needing laser shock strengthening to be covered with a water film with the thickness of 1mm, then carrying out laser shock on the 8Cr4Mo4V rotary bending piece, selecting the output energy of a laser to be 8J, the laser pulse width to be 15Ns, the side length of the laser square spot to be 4mm, and controlling the lap ratio to be 30%.
Step six: and taking down the 8Cr4Mo4V rotary bending piece subjected to laser shock strengthening, removing an absorption layer on the surface of the 8Cr4Mo4V rotary bending piece, cleaning the 8Cr4Mo4V rotary bending piece by using absolute ethyl alcohol, removing colloid on the surface due to high temperature, and cleaning impurities on the 8Cr4Mo4V rotary bending piece by using an ultrasonic cleaning machine.
The hardness and fatigue limit strength of the 8Cr4Mo4V bearing steel test piece are respectively 835HV1 and 990MPa measured by a Vickers hardness tester and a rotary bending fatigue tester.
Comparative example 3.
The method comprises the following steps: putting the 8Cr4Mo4V rotary bending piece into a vacuum furnace, setting a heat treatment process route of vacuum gas quenching, raising the temperature in the vacuum furnace to 1090 ℃ and preserving the temperature for 32min, then filling 2bar of nitrogen into the vacuum furnace, and then carrying out tempering treatment on the rotary bending piece for 2.5h at 550 ℃ for three times.
Step two: the 8Cr4Mo4V rotary bending piece subjected to vacuum gas quenching is subjected to surface treatment of grinding and polishing to remove oxides on the surface of the 8Cr4Mo4V rotary bending piece, so that the 8Cr4Mo4V rotary bending piece is conveniently subjected to next laser shock peening, and the weakening influence of the oxides on the laser shock peening degree is eliminated.
Step three: cleaning impurities on the surface of the 8Cr4Mo4V rotary bending piece by using an ultrasonic cleaner and absolute ethyl alcohol, drying the part by blowing cold air by using a blower, uniformly sticking a black adhesive tape on an area to be subjected to laser shock strengthening on the surface of the 8Cr4Mo4V rotary bending piece as an absorption protective layer, wherein the absorption protective layer is tightly attached to the surface of the 8Cr4Mo4V rotary bending piece, and bubbles, dust, impurities and the like cannot appear.
Step four: fixing the 8Cr4Mo4V rotary bending piece on a manipulator by using a clamp, moving the manipulator to enable a laser square spot to fall in an area needing laser shock strengthening on the surface of the 8Cr4Mo4V rotary bending piece, then adjusting a water path to enable the surface of the 8Cr4Mo4V rotary bending piece needing laser shock strengthening to be covered with a water film with the thickness of 1mm, then carrying out laser shock on the 8Cr4Mo4V rotary bending piece, selecting the output energy of a laser to be 8J, the laser pulse width to be 15Ns, the side length of the laser square spot to be 4mm, and controlling the lap ratio to be 30%.
Step five: and taking down the 8Cr4Mo4V rotary bending piece subjected to laser shock strengthening, removing an absorption layer on the surface of the 8Cr4Mo4V rotary bending piece, cleaning the 8Cr4Mo4V rotary bending piece by using absolute ethyl alcohol, removing colloid on the surface due to high temperature, and cleaning impurities on the 8Cr4Mo4V rotary bending piece by using an ultrasonic cleaning machine.
The hardness and fatigue limit strength of the 8Cr4Mo4V bearing steel test piece were measured to be 800HV1 and 950MPa, respectively, using a Vickers hardness tester and a rotary bending fatigue tester.
Claims (6)
1. A laser shock peening method for improving fatigue life of stabilized 8Cr4Mo4V aviation bearing steel comprises the following steps:
the method comprises the following steps: carrying out quenching and tempering heat treatment on the 8Cr4Mo4V aviation bearing steel part;
step two: carrying out tertiary stabilization treatment on the 8Cr4Mo4V aviation bearing steel part;
step three: removing an oxide layer on the surface of the 8Cr4Mo4V aviation bearing steel part due to heat treatment in a coarse grinding mode;
step four: cleaning the surface of the 8Cr4Mo4V aviation bearing steel part by using an ultrasonic cleaner and absolute ethyl alcohol, and attaching an absorption protective layer to an area of the 8Cr4Mo4V aviation bearing steel part, which needs to be subjected to laser shock strengthening;
step five: clamping the 8Cr4Mo4V aviation bearing steel part on a manipulator, moving the manipulator to enable laser square spots to fall on an area, needing laser shock strengthening, on the surface of the 8Cr4Mo4V aviation bearing steel part, adjusting a water channel to enable the surface of the 8Cr4Mo4V aviation bearing steel part needing laser shock strengthening to be covered with a 1-2mm water film, and then carrying out laser shock on the surface of the 8Cr4Mo4V aviation bearing steel part;
step six: after the laser shock strengthening is finished, taking down the 8Cr4Mo4V aviation bearing steel part, putting the aviation bearing steel part into an ultrasonic cleaning machine, cleaning the aviation bearing steel part with absolute ethyl alcohol, and drying the aviation bearing steel part with cold air for later use;
step seven: the 8Cr4Mo4V aviation bearing steel parts are ground and polished by using grinding sandpaper with the granularity of 600, 1000, 2000, 5000 and 6000 respectively.
2. The laser shock peening method for improving fatigue life of stabilized 8Cr4Mo4V aviation bearing steel according to claim 1, wherein the laser shock peening method comprises the following steps: in the first step, the vacuum quenching treatment condition is 1080-1100 ℃, the heat preservation time is 22-42min, the temperature of the third tempering treatment is 540-560 ℃, and the heat preservation time is 1.5-3.5 h.
3. The laser shock peening method for improving fatigue life of stabilized 8Cr4Mo4V aviation bearing steel according to claim 1, wherein the method comprises the following steps: in the second step, the stabilization treatment mode of the 8Cr4Mo4V bearing steel is three times of stabilization treatment, the conditions are that the temperature of cold treatment is minus 80 ℃ to minus 60 ℃, the temperature is kept for 1.5 to 3.5 hours, the temperature of heat treatment is 430 ℃ to 500 ℃, the temperature is kept for 1.5 to 3.5 hours, and one time of cold treatment and one time of heat treatment is one time of stabilization treatment.
4. The laser shock peening method for improving the fatigue life of the stabilized 8Cr4Mo4V aviation bearing steel according to claim 1, wherein the laser shock peening method comprises the following steps: and in the fourth step, the absorption protective layer is any one of a black adhesive tape, black paint or aluminum foil.
5. The laser shock peening method for improving fatigue life of stabilized 8Cr4Mo4V aviation bearing steel according to claim 1, wherein the laser shock peening method comprises the following steps: in the fifth step, the pulse width of the laser shock peening parameter selection range is 15Ns-21Ns, the laser output power is 3J-8J, the side length of a laser square spot is 3.5mm-4.5mm, and the lap joint rate of the square spot is 25% -50%.
6. The laser shock peening method for improving fatigue life of stabilized 8Cr4Mo4V aviation bearing steel according to claim 1, wherein the laser shock peening method comprises the following steps: and seventhly, grinding the surface damage of the bearing steel with the surface damage after the laser shock strengthening, wherein the grinding amount of the bearing steel is 10-30 microns.
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