GB2614984A - Room-temperature nitriding process based on thermal-mechanical effects of laser, and processing device - Google Patents
Room-temperature nitriding process based on thermal-mechanical effects of laser, and processing device Download PDFInfo
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- GB2614984A GB2614984A GB2304209.6A GB202304209A GB2614984A GB 2614984 A GB2614984 A GB 2614984A GB 202304209 A GB202304209 A GB 202304209A GB 2614984 A GB2614984 A GB 2614984A
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- 230000000694 effects Effects 0.000 title claims abstract description 55
- 238000000034 method Methods 0.000 title claims abstract description 48
- 238000005121 nitriding Methods 0.000 title claims abstract description 47
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 claims abstract description 27
- 125000004433 nitrogen atom Chemical group N* 0.000 claims abstract description 21
- 230000001678 irradiating effect Effects 0.000 claims description 2
- 230000007547 defect Effects 0.000 abstract description 9
- 238000005728 strengthening Methods 0.000 abstract description 9
- 239000013078 crystal Substances 0.000 abstract 1
- 239000000463 material Substances 0.000 description 14
- 239000010410 layer Substances 0.000 description 13
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 8
- 238000010438 heat treatment Methods 0.000 description 8
- 230000035515 penetration Effects 0.000 description 8
- 239000002912 waste gas Substances 0.000 description 8
- 239000007789 gas Substances 0.000 description 7
- 238000003860 storage Methods 0.000 description 6
- 229910001069 Ti alloy Inorganic materials 0.000 description 5
- 238000009792 diffusion process Methods 0.000 description 5
- 229910052757 nitrogen Inorganic materials 0.000 description 5
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 4
- 239000002041 carbon nanotube Substances 0.000 description 4
- 229910021393 carbon nanotube Inorganic materials 0.000 description 4
- 230000035939 shock Effects 0.000 description 4
- 239000000126 substance Substances 0.000 description 4
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 description 3
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 3
- 238000005516 engineering process Methods 0.000 description 3
- 150000002500 ions Chemical class 0.000 description 3
- 230000008018 melting Effects 0.000 description 3
- 238000002844 melting Methods 0.000 description 3
- 239000000843 powder Substances 0.000 description 3
- 239000010936 titanium Substances 0.000 description 3
- 229910000831 Steel Inorganic materials 0.000 description 2
- ATJFFYVFTNAWJD-UHFFFAOYSA-N Tin Chemical compound [Sn] ATJFFYVFTNAWJD-UHFFFAOYSA-N 0.000 description 2
- 230000015572 biosynthetic process Effects 0.000 description 2
- 238000000576 coating method Methods 0.000 description 2
- 239000010432 diamond Substances 0.000 description 2
- 229910003460 diamond Inorganic materials 0.000 description 2
- 238000004880 explosion Methods 0.000 description 2
- 238000002309 gasification Methods 0.000 description 2
- -1 nitrogen ions Chemical class 0.000 description 2
- 238000007711 solidification Methods 0.000 description 2
- 230000008023 solidification Effects 0.000 description 2
- 239000010959 steel Substances 0.000 description 2
- 239000002344 surface layer Substances 0.000 description 2
- VHUUQVKOLVNVRT-UHFFFAOYSA-N Ammonium hydroxide Chemical compound [NH4+].[OH-] VHUUQVKOLVNVRT-UHFFFAOYSA-N 0.000 description 1
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 description 1
- 229910045601 alloy Inorganic materials 0.000 description 1
- 239000000956 alloy Substances 0.000 description 1
- 235000011114 ammonium hydroxide Nutrition 0.000 description 1
- 125000004429 atom Chemical group 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 239000003575 carbonaceous material Substances 0.000 description 1
- 239000011248 coating agent Substances 0.000 description 1
- 230000002301 combined effect Effects 0.000 description 1
- 230000002708 enhancing effect Effects 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 239000002159 nanocrystal Substances 0.000 description 1
- 230000008520 organization Effects 0.000 description 1
- 238000002360 preparation method Methods 0.000 description 1
- 238000004321 preservation Methods 0.000 description 1
- 230000001737 promoting effect Effects 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
- 230000002194 synthesizing effect Effects 0.000 description 1
- 229910052719 titanium Inorganic materials 0.000 description 1
Classifications
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- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C8/00—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
- C23C8/06—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using gases
- C23C8/08—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using gases only one element being applied
- C23C8/24—Nitriding
-
- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C8/00—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
- C23C8/06—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using gases
- C23C8/36—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using gases using ionised gases, e.g. ionitriding
Abstract
A room-temperature nitriding process based on thermal-mechanical effects of laser, and a processing device. The method comprises the following steps: at room temperature, a sealed box (9) where a workpiece to be nitrided is placed is filled with ammonia gas; a first laser beam and second laser beams having different energies are output by means of a diffractive beam splitter (2); several second laser beams are focused above the surface of the workpiece (14), and the ammonia gas is ionized by the thermal effect of laser to form free nitrogen atoms; several second laser beams are distributed around the first laser beam, the first laser beam irradiates the surface of the workpiece (14), plasma generated by laser carries the nitrogen atoms into the surface of the workpiece (14) along with dislocation motion induced by the mechanical effect. Using the thermal and mechanical effects of laser to perform surface strengthening treatment can obtain higher strength, hardness, and fatigue performance than a single strengthening treatment. In addition, room-temperature nitriding can improve the defect of coarse crystal grains caused by conventional high-temperature nitriding.
Description
DESCRIPTION
ROOM-TEMPERATURE NITRIDING PROCESS BASED ON
THERMAL-MECHANICAL EFFECTS OF LASER, AND PROCESSING DEVICE
TECHNICAL FIELD
The present invention relates to the technical field of heat treatment or surface nitriding, and in particular to a normal-temperature nitriding process based on a thermal-mechanical effect of laser and a processing device therefor.
BACKGROUND
INitriding technology is generally a chemical heat treatment process that infiltrates nitrogen. atoms into a surface of a workpiece at a high temperature. The traditional gas nitriding is implemented by placing a. workpiece in an airtight container, introducing flowing ammonia gas, carrying out heating, and carrying out heat preservation for a long time so that the ammonia gas is thermally decomposed to Cr) generate active nitrogen atoms which are continuously adsorbed to the surface of the workpiece and diffuse into the surface layer of the workpiece, thereby changing the chemical composition and 0 organization of the surface layer, as disclosed in Chinese Patent Application No. 202010284906.6 for invention, but there are the following disadvantages of part deformation caused by high temperature, large tensile stress, and easy formation of high-temperature cracks. Chinese Patent Application No. 201710591680.2 for invention discloses a method for preparing TiN gradient coatings on a surface of a titanium alloy with a low laser power, where an all-solid-state thermal effect of laser (heating and melting) is used to promote the self-diffusion of nitrogen atoms to achieve TiN coating preparation. However, this method has die following disadvantages: 1 The thermal effect of laser will still lead to part deformation, large tensile stress, and easy formation of high-temperature cracks. 2. The use of self-diffusion nitriding results in a low nitrogen content of the nitrided layer.
In order to improve the nitriding effect and increase the thickness of the nitrided layer, some pretreatment operations can be carried out to achieve this purpose. Chinese Patent Application Nos. 201810123908.X and 201210492108.8 for invention respectively disclose a laser shock process to improve the efficiency of ion nitriding and a method for enhancing penetration by laser plasma shock wave in a chemical heat treatment process. They both use a laser-induced mechanical effect to produce plastic, deformation on the surface of the material, form high-density dislocations, refine grains and even
DESCRIPTION
produce nanocrystals, thereby promoting the diffusion of nitrogen atoms. However, the above-mentioned technologies or methods still require the traditional high-temperature nitriding process, resulting in defects such as high-temperature deformation; tensile stress, and high-temperature cracks. Chinese Patent Application No. 201811160014.4 for invention discloses a laser high-temperature shock-nitriding combined processing device and method. High-temperature gas nitriding and high-temperature assisted laser shock strengthening are performed in sequence. Laser-induced mechanical effect is mainly used to prepare dislocations, dislocation entanglement and sub-gain boundaries, thereby achieving a certain effect of penetration promotion. However, this method also has some defects. Firstly, the gas nitriding treatment takes a long time and requires a high temperature, which will cause coarse grains and shallow pressure stress; moreover, penetration cannot be dynamically promoted by virtue of a dislocation slip process, thereby reducing the effect of penetration promotion with laser. Chinese Patent Application No. 03141802.3 discloses a method for combined treatment of a material with icrowave plasma and laser at room temperature, where microwave discharge is used to generate plasma, and then ion penetration is implemented under the thermal effect of laser (heating, melting, and solidification). However, this method also has the following technical elects. 1 Due to use of two energy sources of microwave and laser, the processing technology is relatively complicated. 2. Although ion penetration is realized in a normal temperature environment, the thermal effect (heating, melting, and solidification) of laser will still cause cracks on the surface of a material, tensile stress and other defects.
Chinese Patent Application No. 201110367288.2 for invention in the prior art discloses a method and device for continuously synthesizing a diamond film by radiating carbon nanotubes with strong laser. The laser is reflected and split by a. spectroscope to generate two laser beams.
One of the laser beams acts on non-transparent carbon nanotube powder which is bombarded into the surface of a base after gasification explosion. The other laser beam is used for heating to form high-temperature micro-regions, which promotes the entry of carbon nanotube powder and finally forms a diamond film. This patent has the following disadvantages: 1. The method of using laser to induce gasification and explosion of the non-transparent carbon nanotube powder, and then bombarding a carbon material into the surface of the base cannot be applied to transparent gases/liquids such as ammonia gas and ammonia water, and it is difficult to be used for nitriding treatment. 2. High-temperature micro-regions are formed on the surface of the
DESCRIPTION
material, and there are still defects such as high-temperature tensile stress and cracks. 3. The penetration of the material is achieved by bombardment and diffusion, and the penetration effect is poor.
SUMMARY OF THE INVENTION
Aiming at defects such as high-temperature tensile stress and cracks in the prior art, the present invention provides a normal-temperature nitriding process based on a thermal-mechanical effect of laser and a processing device therefor. According to the present invention, ammonia gas is ionized through a thermal effeLt of laser, so that more nitrogen atoms are adsorbed on the surface of a sample. The moving dislocations/grain boundaries are used as nitriding channels, which can increase the thickness of a nitrided layer, and defects such as coarse grains, high-temperature tensile stress cracks in traditional high-temperature nitriding-induced materials can al so be avoided. High-density dislocations are induced on the surface of the material, and nitrogen atoms penetrate into the material along the grain boundaries and dislocations, which helps to further improve the strength, hardness and fatigue properties of the nitrided layer.
The present invention achieves the above-mentioned technical effect through the following technical solutions.
A normal-temperature nitriding process based on a thermal-mechanical effect of laser includes the following steps: filling an airtight box containing to-be-nitrided (Apiece s at MO temperature; outputting first laser beams and second laser beams of different energies through a diffractive beam splitter focusing some of the second laser beams over a surface of the workpiece and ionizing the ammonia gas by a thermal effect of laser to form free nitrogen atoms; distributing some of the second laser beams around the first laser beams, and irradiating the surface of the workpiece with the first laser beams so that plasma generated by the laser carries the nitrogen atoms into the surface of the workpiece along moving dislocations induced by a mechanical effect.
Further, the first laser beam has less energy than the second laser beam.
DESCRIPTION
Further, an energy ratio of the first laser beam to the second laser beam is 4:6.
Further, a focus of the first laser beams is 3-10mm below the surface of the workpiece; a focus of the second laser beams is 0.2-0.5mm above the surface of the workpiece.
Further, a spot formed after the first laser beams are focused has a diameter not less than mm, and a spot formed after the second laser beams are focused has a diameter of 0.2-0.8 mm.
A processing device for a non I-temperature nitriding process based on a thermal-mechanical effect of laser includes a laser device, an airtight box, a dill-lac:dye beam splitter and an ammonia gas device. A to-be-nitrided workpiece is placed in the airtight box, the laser device is configured to emit laser, and the diffractive beam splitter is configured to split the laser emitted by the laser device into first laser beams and second laser beams of different energies. Some of the second laser beams are distributed around the first laser beams. Some of the second laser beams pass through the airtight box and focus above a surface of the workpiece. The first laser beams pass through the airtight box and focus on the surface of the workpiece. The airtight box communicates with the ammonia gas device.
The processing device for a normal-temperature nitriding process based on a thermal-mechanical effect of laser further includes an assembled lens A, an assembled lens B, a reflecting mirror and focusing mirrors. The first laser beams and the second laser beams pass through the assembled lens A, the reflecting mirror and the assembled lens B and then enter the airtight box. The assembled lens A is configured to collimate the first laser beams and the second laser beams, and the assembled lens B is configured to deflect the first laser beams and the second laser beams. The focusing mirrors are installed in the airtight box to focus the deflected first laser beams and second laser beams on the to-be-nitrided workpiece.
The present invention has the following beneficial effects: 1. According to the normal-temperature nitriding process based on the thennal effect of laser, ammonia gas is ionized through the thermal effect of laser, so that more nitrogen atoms are adsorbed on the surface of a sample The moving dislocations/grain boundaries are used as nitriding channels, which can increase the thickness of a nitrided layer, and the defect of coarse grains in traditional high-temperature nitriding-induced materials can also he avoided. High-density dislocations are induced by the mechanical effect of laser on the surface of the
DESCRIPTION
material, and plasma generated by laser shock strengthening is used as a carrier and can carry nitrogen atoms along the grain boundaries and moving dislocations to penetrate into the material, which helps to further improve the strength, hardness and fatigue properties of the nitrided layer.
2. The normai-temperature nitriding process based on the thermal-mechanical effect of laser described in the present invention which uses the thermal-mechanical combined effect of laser to carry out surface strengthening treatment can obtain higher strength, hardness and fatigue properties than single strengthening treatment.
3. in the normal-temperature nitriding process based on c tanical effect of laser described in the present invention, multiple laser beams act on ammonia gas, and by using relatively high laser energy at a focal point, the transparent ammonia gas is ionized to form free nitrogen ions. While the thermal effect of the laser induces the generation of nitrogen ions, the mechanical effect of the laser is used to induce dislocation slip and grain boundary movement, and the nitrogen atoms formed by ionization are brought deep into the base with the dislocation slip and grain boundary movement, forming a thick and uniform nitrided layer.
4. The normal-temperature nitriding process based on a thermal-mechanical effect of laser described in the present invention forms defects such as subgrain boundaries and dislocations on the surface and high-amplitude residual pressure stress and can promote the diffusion of nitrogen atoms into the base along the moving dislocations which helps to farther increase the thickness and nitrogen content of the nitrided layer.
5. The processing device for the normal-temperature nitriding process based on a thermal-mechanical effect of laser according to the present invention reduces the clamping time of materials in the combined processing process, improves work efficiency, and is more convenient to operate. in addition, the device of the present invention performs nitriding at room temperature, which greatly shortens the processing time compared with the traditional nitriding process which requires high-temperature treatment.
BRIEF DESCRIPTION OF DRAWINGS
FIG. 1 is a schematic diagam of the processing device for a normal-temperature nitriding
DESCRIPTION
process based on laser thermal-mechanical effect according to the presentinvention; :FIG 2 shows surface microhardness of a. TC4 titanium alloy under different treatment methods; FIG. :3 shows a cross-section structure of base of a 17(:4 titanium alloy; FIG. 4 shows a cross-section structure of a TC4 titanium alloy after traditional gas nit riding; and FIG, 5 shows a cross-section structure of a TC4 titanium alloy after laser nitrid In the drawings: 1-laser device; 2-diffractive beam splitter; 3-assembled lens A; 4-pressure sensor; flow valve; 6-reflecting mirror; 7-assembled lens 8-high-temperature and high-pressure resistant quartz glass; 9-airtight box; 10-outlet flow valve; 11-waste gas storage tank; 12-first focusing mirror; 's linkage workbench; 14-workpiece; 15-second focusing mirror; 16-ammonia gas tank; and 17-computer.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
The present invention will be further described below in conjunction with the drawings and embodiments, and is not for use in limiting the protection scope of the in ention As shown in FIG. 1, the processing device for the normal-temperature nitriding process based on the thermal-mechanical effect of laser according to the present invention includes a laser device an airtight box 9, a diffractive beam splitter 2, an assembled lens A3, an assembled lens B7, a reflecting mirror 6., a first focusing mirror 12, a second focusing mirror 15 and art ammonia gas tank 16. A to-be-nitrided workpiece 14 is placed in the airtight box 9, and a three-axis linkage workbench 13 is arranged at a bottom of the workpiece 14 and configured for three-dimensional movement of the to-be-nitrided workpiece 14. High-temperature and high-pressure resistant quartz glass 8 is installed on an upper part of the airtight box 9, the laser irradiates the workpiece 14 through the high-temperature and high-pressure resistant quartz glass S. and the ammonia gas tank 16 and a waste gas storage Lank I are respectively connected to the airtight box 9 through an air pipe. An inlet flow valve 5 is arranged between the ammonia gas tank 16 and the airtight box 9, and an outlet flow valve 10 is arranged between the waste gas storage tank 11 and the airtight box 9. When the
DESCRIPTION
process goes to working with ammonia gas, the air pressure is maintained at 150-300Pa. According to information fed back by a pressure sensor 4, a computer 17 adjusts the inlet flow valve and the outlet flow valve to realize closed-loop control over the pressure in the airtight box The laser device 1 is configured to emit laser, and the laser device 1 is configured as a nanosecond pulsed laser device with a laser pulse width of 20-25 ns. The diffractive beam splitter 2 is configured to split the laser emitted by the laser device I into first laser beams and second laser beams of different energies. Some of the second laser beams are distributed around the first laser beams. Some of the second laser beams pass through the airtight box 9 and focus above a surface of the workpiece. The first laser beams pass through the airtight box 9 and focus on the surface of the workpiece. The airtight box 9 communicates with the ammonia gas device. The first laser beams and the second laser beams pass through the assembled lens A 3, the reflecting mirror 6 and the assembled lens B 7and then enter the airtight box 9. The assembled lens A 3 is configured to collimate the first laser beams and the second laser beams, and the assembled lens B 7 is configured to deflect the first laser beams and the second laser beams. The focusing mirrors 12 and 15 are installed in the airtight box 9 to focus the deflected first laser beams and second laser beams on the to-be-nitrided workpiece.
Example 1
A case of Cr12MoV nitrided steel with a size of 30mrn30mnv<5rnm will he described below as an example, and the normal-temperature nitriding process based on the thermal-mechanical effect of laser described in the present invention is carried out for surface strengthening treatment. Specific steps are as follows.
The to-be-nitrided workpiece 14 is polished to a mirror surface with;4400-42000 SiC sandpaper, ultrasonically cleaned with anhydrous ethanol, and then placed on the three-axis linkage workbench 13.
The pressure sensor 4 is turned on, ammonia gas is introduced, and according to the information fed back by the pressure sensor 4, the computer adjusts the inlet flow valve and the outlet flow valve to realize the closed-loop control over the pressure in the airtight box and control the pressure in the airtight box to be around 200Pa.
DESCRIPTION
After the pressure in the airtight box is stable, parameters of e laser device I are set to have a pulse width of 25ns and a laser energy of 30j.
The diffractive beam splitter 2 is then turned on to split the laser emitted by the laser device 1 into first laser beams and second laser beams of different energies. Some of the second laser beams are focused over the surface of the to-be-nitrided workpiece and the ammonia gas is ionized by the thermal effect of laser to form free nitrogen atoms. Some of the second laser beams are distributed around the first laser beams, and the to-he-nitrided workpiece 14 is irradiated with the first laser beams so that plasma generated by the laser carries the nitrogen atoms into the surface of the workpiece along moving dislocations induced by mechanical effect. The energy of the first laser beam is 12J and the energy of the second laser beam is I Si.
The spot diameters of the laser beams are adjusted by the focusing mirrors, the spot size of the first laser beam is 3mm, and the focal point of the second laser beam is at a height of 0.3 mm from the surface of the workpiece, with a corresponding spot of 0.6 mm in size.
The three-axis linkage worktable 13 moves along a predetermined path until the processing is completed, and in this process, it is ensured that the spot overlap rate corresponding to the mechanical effect is 50%.
After the processing is finished, waste gas in the airtight box is collected in the waste gas storage tank, and then the workpiece is unloaded.
The laser device, the diffractive beam splitter, and the pressure sensor are turned off The thickness of the nitrided layer of the processed Cr] 2MoV workpiece is expected to reach 60-70 [un, and a connection line between the nitrided layer and the base material can be relatively flat.
Example 2
A case of 38CrilloA1 nitrided steel with a size of 20mms20rm 5mm will be described below as an example, and the normal-temperature nitriding process based on the thermal-mechanical effect of laser described in the present invention is carried out for surface strengthening treatment. Specific steps are as follows.
DESCRIPTION
The to-be-nitrided workpiece 14 is polished to a mirror surface with #400-#2000 SiC sandpaper, ultrasonically cleaned with anhydrous ethanol, and then placed on the three-axis linkage workbench 13.
The pressure sensor 4 is turned on, ammonia gas is introduced, and according to the information fed back by the pressure sensor 4, the computer adjusts the inlet flow valve and the outlet flow valve to realize the closed-loop control over the pressure in the airtight box and control the pressure in the airtight box to be around 240Pa.
After the pressure in the airtight box is stable, parameters of the laser device I are sett() have a pulse width of 20ns and a laser energy of 207.
The diffractive beam splitter 2 is then turned on to split the laser emitted by the laser device I into first laser beams and second laser beams of different energies. Some of the second laser beams are focused over the surface of the to-beimitrided workpiece and the ammonia gas is ionized by the thermal effect of laser to form free nitrogen atoms. Some of the second laser beams are distributed around the first laser beams, and the tobe-niirided workpiece 14 is irradiated with the first laser beams so that plasma generated by the laser carries the nitrogen atoms into the surface of the workpiece along moving dislocations induced by mechanical effect. The energy of the first laser beam is Sj and the energy of the second laser beam is 12j.
The spot diameters of the laser beams are adjusted by the focusing mirrors, the focal point of the first laser beam is located 10 mm below the surface of the workpiece, with a corresponding spot size of 6 mm in size, and the focal point of the second laser beam is at a height of 0.5 mm from the surface of the workpiece, with a corresponding spot of 0.8 mm in size The three-axis linkage worktable moves along a predetermined path until the processing is completed, and in this process, it is ensured that the spot overlap rate corresponding to the mechanical effect is 50%.
After the processing is finished, waste gas in the airtight box collected in the -as as storage tank, and then the workpiece is unloaded.
The laser device, the diffractive beam splitter, and the pressure sensor are turned off
DESCRIPTION
The thickness of the nitrided layer of the processed 38CrMoAl workpiece is expected to reach 280-300 um, and a connection line between the nitrided layer and the base material can be relatively flat.
Example 3
A case of TC4 aere, titanium alio with a size of 2f mx2Ommx2mm will be described as an example, and the normal-temperature nitriding process based on the thermal-mechanical effect of laser described in the present invention is carried out for surface strengthening treatment. Specific steps are as follows.
The to-be-nitrided,7% orkpiece 14 is polished to a mirror surface with ff400-4f2000 SiC sandpaper, ultrasonically cleaned with anhydrous ethanol, and then placed on the three-axis linkage workbench 13.
The pressure sensor 4 is turned on, ammonia gas is introduced, and according to the information fed back by the pressure sensor 4, the computer adjusts the inlet flow valve and the outlet flow valve to realize the closed-loop control over the pressure in the airtight box and control the pressure in the airtight box to be around 270Pa..
After the pressure in the airtight box is stable, parameters of the laser device I are set to have a pulse width of 25ns and a laser energy of 40j.
The diffractive beam splitter 2 is then turned on to split the laser emitted by the laser device 1 into first laser beams and second laser beams of different energies. Some of the second laser beams are focused over the surface of the to-be-nitrided workpiece and the ammonia gas is ionized by the thermal effect of laser to form free nitrogen atoms. Some of the second laser beams are distributed around the first laser beams, and the to-be-nitrided workpiece 14 is irradiated with the first laser beams so that plasma generated by the laser carries the nitrogen atoms into the surface of the workpiece along moving dislocations induced by mechanical effect. The energy of the first laser beam is 16j and the energy of the second laser beam is 24J.
The spot diameters of the laser beams are adjusted by the focusing mirrors, the focal point of the first laser beam is located 6 mm below the surface of the workpiece, with a corresponding spot size of 4 mm in size, and the focal point of the second laser beam is at a
DESCRIPTION
height of 0.2 mm from the surface of the workpiece, with a corresponding spot of 0.2 mm in size The three-axis linkage worktable H moves along a predetermined path until the processing is completed, and in this process, it is ensured that the spot overlap rate coniesponding to the mechanical effect is 50%.
After the processing is finished, waste gas in the airtight box is collected in the waste gas storage tank, and then the workpiece is unloaded The laser device, the diffractive beam splitter, and the pressure sensor are turned off.
It can be seen from FIG. 2 that a TC4 workpiece after laser nitriding has a Vickers hardness of I306.5H V, which is 272.3% and 18.1% higher than that of a base and that by the traditional gas ni tri ding respectively.
It can be seen from FIGS 3, 4 and 5 that the cross-sectional structure of a base of a TC4 alloy mainly includes 6,-Ti and 13-Ti, and the thickness of the nittided layer on the surface of the TC4 workpiece after laser nitriding, can reach 26.3 gm which is 42.9% higher than that by gas nitriding.
Without deviating from the substance of the invention, any sImple improvement, equivalent substitution, and modification that can be made by those skilled in the art of this invention should be covered in the protection scope of the invention.
Claims (7)
- CLAIMS1. A normal-temperature nitriding process based on a thermal-mechanicaL effect of laser, characterized by comprising the following steps: filling an airtight box-containing a to-be-nitrided workpiece with ammonia gas at room tern perani re; outputting first laser beams and second laser beams of different energies through a diffractive beam splitter (2); focusing some of the second laser beams over a surface of the workpiece and ionizing the ammonia gas by a thermal effect of laser to form free nitrogen atoms; distributing some of the second laser beams around the first laser beams, and irradiating the surface of the workpiece with the first laser beams so that plasma generated by the laser carries the nitrogen atoms into the surface of the workpiece along moving dislocations induced by a mechanical effect.
- 2. The normal-temperature nitriding process based on a thermal-mechanical effect of laser according to claim 1, characterized in that the first laser beam has less energy than the second laser beam.
- 3. The normal-temperature nitriding process based on a thermal-mechanical effect of laser according to claim 1, characterized in that an energy ratio of the first laser beam to the second laser beam is 4:6.
- 4 The normal-temperature nitriding process based on a thermal-mechanical etièct of laser according to claim 1, characterized in that a spot formed after the first laser beams are focused has a diameter not less than 3 mm, and a spot formed after the second laser beams are focused has a diameter of 0.2-0.8 mm.
- 5. The normal-temperature nitriding process based on athermal-mechanical effect of laser according to claim 1, characterized in that a focus of the second laser beams is 0.2-0.5mm above the surface of the workpiece, and a focus of the first laser beams is 3-10mm below the surface of the workpiece 6. A processing device of the normal-temperature nitriding process based on a thermal-mechanical effect of laser according to claim I, characterized by comprising a laser device (1), an airtight box (9), a diffractive beam splitter (2) and an ammonia gas device, a to-be-nitrided workpiece is placed in the airtight box (9), the laser device (.1) is
- CLAIMSconfigured to emit laser, and the diffractive beam splitter (2) is configured to split the laser emitted by the laser device (1.) into the first laser beams and the second laser beams of different energies; some of the second laser beams are distributed around the first laser beams, some of the second laser beams pass through the airtight box (9) and focus above the surface of the workpieee, the first laser beams pass through the airtight box (9) and focus on the surface of the wortcpiece, and the airtight box (9) communicates with the ammonia gas device.
- 7. The processing device of the normal-temperature nitriding process based on a thermal-mechanical effect of laser according to claim 1, characterized in that the processing device further comprises: an assembled lens A (4, an assembled lens B (7), a reflecting mirror (6) and focusing mirrors (12; 15); the first laser beams and the second laser beams pass through the assembled Lens A (3), the reflecting mirror (6) and the assembled lens B (7) in sequence, and then enter the airtight box (9); the assembled lens A (3) is configured to collimate the first laser beams and the second laser beams, and the assembled lens B (7) is configured to deflect the first laser beams and the second laser beams; the focusing mirrors (12, 15) are installed in the airtight box (9) to focus the first laser beams and the second laser beams after deflection on the to-be-nitrided workpiece.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202010950538.4A CN112226724B (en) | 2020-09-11 | 2020-09-11 | Normal-temperature nitriding process and processing device based on laser thermal-mechanical effect |
| PCT/CN2020/133238 WO2022052334A1 (en) | 2020-09-11 | 2020-12-02 | Room-temperature nitriding process based on thermal-mechanical effects of laser, and processing device |
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| GB202304209D0 GB202304209D0 (en) | 2023-05-10 |
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| GB2614984B GB2614984B (en) | 2024-02-14 |
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| CN113026000B (en) * | 2021-04-02 | 2022-12-09 | 泰杋科技股份有限公司 | Device and method for preparing tantalum nitride film by precursor coating gas protection laser |
| CN115404436B (en) * | 2022-05-07 | 2024-04-09 | 江苏大学 | Ultrasonic acceleration-based surface strengthening device and method |
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- 2020-09-11 CN CN202010950538.4A patent/CN112226724B/en active Active
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- 2020-12-02 WO PCT/CN2020/133238 patent/WO2022052334A1/en active Application Filing
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Also Published As
| Publication number | Publication date |
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| WO2022052334A1 (en) | 2022-03-17 |
| GB202304209D0 (en) | 2023-05-10 |
| CN112226724A (en) | 2021-01-15 |
| CN112226724B (en) | 2021-08-03 |
| GB2614984B (en) | 2024-02-14 |
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