Some standard content:
ICS 25. 220. 20
National Standard of the People's Republic of China
GB/T18683---.2002
Laser surface hardening of iron and steel parts
Laser surface hardening of iron and steel parts2002-03-10Promulgated
General Administration of Quality Supervision, Inspection and Quarantine of the People's Republic of China
Implementation on 2002-08-01
GB/T 18683--2002
Appendix B of this standard is a normative appendix, and Appendix A is an informative appendix. This standard is proposed by the China Machinery Industry Federation. This standard is under the jurisdiction of the National Technical Committee for Standardization of Metal and Non-metal Coatings. The responsible drafting unit of this standard is Wuhan Institute of Materials Protection. The participating drafting units of this standard are Huazhong University of Science and Technology and Shenyang Continental Laser Equipment Co., Ltd. The main drafters of this standard are: Zhi Lin, Wu Zijian, Wen Meiyi, Tao Xiqi, Tao Zengyi, Tao Xingqi, Duan Xinhua, iYKAONiKAca
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Laser surface quenching of steel parts
GB/T18683—2002
Laser surface quenching is a technology for rapid strengthening of the surface of metal materials and parts, which can improve the surface toughness, strength and wear resistance, while keeping the core of the part with good comprehensive mechanical properties. Since the process is completed under the conditions of local rapid heating and self-quenching, the deformation of the quenched parts can be greatly reduced.
1 Scope
This standard specifies the special requirements for laser surface quenching equipment for steel parts, the original state of steel parts commonly used for laser surface quenching, and the basic requirements for process control, quality control, quality inspection and labor protection of laser surface quenching. This standard applies to laser surface quenching of steel parts. 2 Normative References
The clauses in the following documents become the clauses of this standard through reference in this standard. For all the referenced documents with a date, all the subsequent amendments (excluding the contents of errors) or revisions are not applicable to this standard. However, the parties who reach an agreement based on this standard are encouraged to study whether the latest versions of these documents can be used. For all the referenced documents without a date, the latest versions are applicable to this standard. GB/T1031 Surface roughness parameters and their values (t1S0)468) GB/3505 Surface roughness terminology Surface roughness and its parameters (e9V1SO4287) CB/T4340:1 Metal Vickers hardness test Part 1: Test method (eqIS0)6507) GB/T1312 Metal micro-Vickers hardness test method GB/T7232 Metal heat treatment process terminology
GB/T9790 Vickers and Knoop microhardness test for metal coatings and other related covering layers (neqISO4516) GB7247 Radiation safety of laser products. Equipment classification, requirements and user guide (idtIEC825) GB10320 Electrical safety of laser equipment and facilities (eVIFC820) GB10435 Laser radiation hygiene standard for the workplace 3 Terms and definitions
The terms and definitions established in GB/T7232 and the following terms and definitions apply to this standard. 3.1
Laser surface hardening is a quenching process that uses a biased laser beam as energy to heat the workpiece surface at a very fast speed to open a self-hardening process. The main feature is self-hardening. 3.2
Laser power density Q (W/cm2) Power density of laser beam acting on the surface of the workpiece per unit area SF Laser power P. Q number
GB/T 18683--2002
Scanning speed (mm/s) Scanning speed The distance that the laser spot moves relative to the workpiece in a unit time. 3.4
Phase transformation hardening zone The area where the steel part undergoes organizational changes under laser irradiation, and its composition phase is similar to that obtained by quenching, and the hardness is improved. 3.5
Heat response zone
The area around the phase transformation hardening zone where the organization undergoes partial transformation under the influence of laser irradiation. It is different from the phase transformation hardening zone and the matrix without phase transformation.
The lowest hardness of the surface (HV characteristic) the lowest hardness of the workpiece surface.
Hardness limit (HV group) hardness limit The hardness of the surface. Due to the formula HV = 0. 7XIV City
Other hardness limit values can also be used after consultation between the relevant parties. 3. 8
Effective depth of hardening layer
Effective depth of hardeninglng The maximum vertical distance from the surface of the workpiece to the point where the hardness is equal to the hardness limit. 3.9
Effective width of hardening After a single laser scan, on a cross section perpendicular to the scanning direction, the distance between two points on the surface of the workpiece where the hardness is equal to the hardness limit. 3.10
Total depth of hardening The maximum vertical distance from the workpiece surface to the point where the microhardness or microstructure has no obvious change relative to the underlying substrate material. 3.11
Total width of hardening After single-pass laser scanning, on a cross section parallel to the scanning direction, the distance between two points where the microhardness or microstructure of the workpiece treated surface has no obvious change relative to the underlying substrate material.
4 Material and original state of the workpiece
4.1 Material of the workpiece
All materials that can undergo a molten phase change are suitable for laser surface quenching. Common materials are shown in Appendix A. 4.2 Original state of the workpiece before laser quenching
a) The original surface of the workpiece before laser quenching should be free of contamination, rust, burrs, and carbide, and can be directly processed and laser surface quenched.
b) The original structure of the workpiece should be uniform and fine. Pre-light heat treatments such as annealing, normalizing and annealing should be selected according to the type, composition, purpose and performance requirements of the material (see Appendix A).
5 Basic technical requirements and operating specifications
5.1 Requirements for equipment
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GH/T 18683---2002
Laser equipment used for laser surface annealing includes a laser that generates a laser beam, a light guide and focusing system that guides the transmission of the light beam, a laser processing machine that carries the upper part and makes it move, and other auxiliary devices. 5.1.1 Laser
Whether it is a CO laser or a YAG laser, its output power, beam mode, scanning speed and spot size must meet the technical requirements of the annealing equipment.
The stability of the laser output power and the laser beam mode have a great influence on the laser surface annealing effect. A power monitoring device must be installed and calibrated regularly. For laser surface ignition, the laser should be of a type that can output multi-mode beams; or the beam mode should be processed to make its energy distribution uniform. The power of the YAG laser should be able to output continuously. 5. 1. 2 The light guiding and focusing system
should include devices such as optical axis aiming and pushing, optical transmission and steering, and focusing (a beam expander telescope should be configured if necessary), and the focusing head should have a protective gas transmission and water cooling system. 5. 1. 3 Laser processing machine
According to the shape of the workpiece to be processed, one-dimensional, multi-dimensional automatic or CNC machine tools as follows, as well as other suitable equipment: 5. 1. 4 Auxiliary devices of the laser
) Screen knocking device To prevent the laser from directly radiating or being reflected by the workpiece, diffusely reflecting to the body and eyes of the staff and causing harm, the processing site must be equipped with appropriate shielding devices. b) For the laser surface rate ignition device, it is necessary to determine the path of the scanning beam on the surface of the workpiece to be processed, and the red light generated by the He-Ne laser or the visible light generated by other devices can be used for alignment. 5.2 Surface pretreatment of workpieces wwW.bzxz.Net
is to strengthen the workpiece.In order to prevent the workpiece from absorbing the energy of micro-light radiation, a coating with high absorption capacity for laser should be formed on its surface before laser surface ignition. Generally, phosphating treatment or coating containing various light-absorbing substances is used. The selection of coating should meet the following requirements: a) It can improve the absorption rate of laser energy by the workpiece; b) It has good thermal conductivity, good adhesion to the workpiece before treatment, and good mechanical stability; c) It has no effect on the composition and organizational structure of the laser coating layer; 4) The coating material should not easily induce surface cracks of the treated material; c) The coating process should be simple and the coating should be uniform; g) It has good anti-rust effect and does not corrode the workpiece surface; g) It is easy to clean and remove after treatment or can be assembled and used without cleaning; h) It is not easy to be handled, light-polluted, ground-polluted, and stored. Whether the pretreatment is phosphating or spraying, the surface layer is required to be uniform, the thickness is properly controlled, and the laser hardening area is fully covered.
5.3 Formulation of process specifications
5.3.1 Principles of process formulation
The material, pretreatment conditions, technical requirements (hardness, depth of phase change hardening zone and heat affected zone, metallographic structure before and after treatment, etc.) of the workpiece should all be suitable for the process characteristics of laser surface quenching. 5.3.2 Process parameters and their relationships
The main process parameters of laser surface quenching include laser output power P, spot area acting on the workpiece surface, scanning speed V, etc. The relationship between the depth of laser quenching hardening layer and the main process parameters is as follows: Hsv
5.3.3 When the laser surface quenching area is wide, it is necessary to use the scanning belt overlap method for processing. The overlap coefficient should be taken as 5%~20%, and its calculation formula is as follows:
GB/T 18683—2002
Overlap number-spot-free width×100%
Overlap amount
If conditions permit, a wide beam laser can be used to reduce the number of overlaps. 5.3.4 Determination of process parameters
8) Determine the process parameters (laser power, scanning speed, spot size, etc.) according to the material properties, shape and size surface quality of the workpiece to be processed, equipment conditions, laser beam properties, pretreatment methods and other specific conditions. b) According to the physical characteristics of the workpiece, refer to the existing experimental data to determine the range of process parameters, and determine the process parameters after verification. In the process of determining the process parameters, the influence of surface pretreatment and protective gas should be fully considered. 5.4 Operation records
The operation record should include: workpiece name, material, original state, technical requirements, workpiece shape and processing part, laser equipment number and electrical parameters, 1 working gas composition and flow, pretreatment method, process parameters and processing effect. The record should be signed by the relevant personnel and kept for a period of time.
6 Quality requirements and inspection
The inspector should inspect according to the technical requirements, process documents, sampling method and quantity. 6.1 Appearance
6.1.1 Observe with the naked eye or a low-power magnifying glass. The laser surface blasting surface shall not have cracks, scratches, pits and other defects that affect use. 6-1-2 The scanning tape used to touch the blasting surface may have a slight convex feeling. 6.1.3 The surface of the workpiece that is laser blasted as the last process shall not have any oxidized phenomenon. For workpieces that need to be ground after laser surface blasting, the depth of the laser surface blasting melt layer shall not exceed the subsequent processing allowance. 6.2 Detection of surface roughness
Evaluate the surface roughness of laser surface blasted parts according to GR, T1031 and GB, T3505. For workpieces that are laser blasted as the last process, the surface roughness level shall not be reduced by more than one level after laser surface blasting. 6. 3 Hardness inspection
6.3.1 Surface hardness
Surface hardness should be measured with a Vickers hardness tester (GB/T4340.1) with a load of 9.8N98N or a small load Vickers hardness tester (GB/T4340.1: when the depth of the hardened layer is below 0.2mm, the hardness tester load shall not exceed 49N1. The values obtained by other hardness methods are for reference only.
6.3.2 Hardness distribution
The microhardness method (GB/T4342 and GB/T9790) is used to measure the hardness distribution of the hardened layer after laser surface annealing. The preparation of microhardness specimens is carried out as in 6.4.
The load should be balanced and even during the test, and there should be no impact or vibration. The indentation obtained during the length measurement should be a stem shape with a clear outline to ensure the accuracy of the test results.
6.4 Metallographic inspection
6.4.1 Sampling
The selected metallographic specimens must be typical. Taking full account of the orientation of the measured surface of the sample cutting part, the depth of the laser surface annealing hardening layer, the microstructure and grain size of the hardened area, the cross section perpendicular to the sample surface should be taken as the observation surface. Some workpieces that cannot be sampled directly can be replaced by samples with the same material, the same original state, the same pretreatment method and the same laser surface annealing conditions as the workpiece, but the sample thickness shall not be less than 10mm. When sampling with a cutting machine, water cooling should be continuously sprayed to avoid large changes in the metallographic structure due to heat and external forces. 6.4.2 Sample preparation
1) For materials with uneven structures such as chain notches, the surface hardness after laser surface annealing can be measured by the microhardness method with a load of no more than 1.96N. -HTiKANiKAca-
GB/T 18683—2002
According to the shape and size of the workpiece, different methods are selected to make metallographic samples (mounting or clamping with a splint), and appropriate chemical retardants are used to display their metallographic structures according to different materials. When using a grinding wheel cutter to take samples, the cut section should be ground to remove the surface layer with a thickness of not less than 0.5 mm, and then prepare the metallographic grinding surface.
During the preparation process, the original metallographic structure and hardness of the sample shall not be changed. The grinding of the hardened layer surface shall be minimized as much as possible, and the edge shall not be rounded.
6.4.3 Microstructure
After laser surface quenching, the hardened area of the material shall have a similar organizational structure and composition phase to that of conventional quenching treatment, but the organization is finer and more dispersed.
6.5 Measurement of hardened layer depth
The depth of the laser surface quenched hardened layer is divided into the total hardened layer depth and the effective hardened layer depth. The measurement methods used are microhardness measurement method (see Appendix B) and microstructure measurement method. The hardened layer depth should be measured according to the following method at the specified location or specified area according to the requirements of the drawing. 6.5.1 Microhardness measurement method
H) Measurement principle The hardness distribution of the cross section perpendicular to the sample surface is used to determine the depth of the hardened layer. That is, the hardness value is used as the ordinate and the distance from the measured point to the surface is used as the abscissa. A curve of hardness versus distance is drawn. According to the coordinate value of the hardness limit on the curve and the coordinate value of the point where the basic hardness is initially reached, the effective hardened layer depth and the total hardened layer depth are determined. b) The preparation of the measuring surface is carried out in accordance with 6.1.
c) Measurement method Appendix B.
6.5.2 Microstructure measurement method
a) Measurement principle The depth of the hardened layer after laser surface annealing is determined based on the change in the microstructure from the surface to the core of the workpiece caused by the laser annealing of the part.
b) The preparation of the measuring surface is carried out in accordance with 6, 4. Generally, 2% to 4% alcohol solution of chloroform or other appropriate etchants are used to display the microstructure of the sample (etchants and ordinary etchants are used together). Measurement method (as shown in Figure 1) On the cross section of the sample, the distance (a) measured vertically from the surface to the top of the crescent-shaped heat-affected zone is the total hardened layer depth of the laser surface quenching layer; the distance (a) measured vertically from the surface to the 1/2 of the heat-affected zone in the direction of the crescent bottom is the effective hardened layer depth of the laser surface quenching layer. H
Phase transformation zone
Heat shadow zone
1 Laser surface rate quenching hardening acoustic diagram
6. 6 Measurement of hardening width
6. 6. 1 Microhardness measurement method
a) Measurement principle Determine the hardened layer width according to the hardness distribution of the treated surface. That is, in the direction perpendicular to the laser scanning direction in the treated surface area, with the hardness value as the ordinate and the distance from the substrate to the measuring point as the abscissa, a curve of hardness versus distance is drawn. According to the coordinate value of the hardness limit point on the curve and the hardness value of the point where the substrate hardness begins to be reached, the effective hardened layer width and the hardness of the hardened layer are determined. b) The preparation of the measuring surface is carried out according to 6.4. c) The measurement method is shown in the appendix. GB/T18683—2002 6.6-2 Microstructure measurement method (Measuring principle) The hardened layer width is determined based on the difference between the phase transformation hardening zone, heat affected zone and substrate structure of the workpiece after laser surface annealing treatment.
b) Preparation of the measuring surface shall be carried out in accordance with 6.4
c) Measurement method (as shown in Figure 1) On the cross section perpendicular to the laser scanning force direction, the widest part of the small tooth heat affected zone is the total hardened layer width (H), and the distance between the 1/2 of the two ends of the heat affected zone is the effective hardened layer width (H,6.7 Arbitration method
In case of dispute, the microscopic sintering method shall be used as the arbitration method for determining the depth and width of the hardened layer. 7 Safety protection
In order to prevent laser auxiliary radiation or scattering, the operator shall use personal protective equipment. According to the laser noise period, wavelength and output power (radiation power) or output energy (auxiliary radiation energy), etc., choose appropriate protective glasses, gloves and protective clothing.
Other safety protection shall be implemented in accordance with GB10320.GB7217 and GB10435, HKANTKAa-
Steel type
Carbon structural steel
Alloy structural steel
Bearing steel
Elastic steel
Carbon T. Tool steel
Taiwanese tool steel
High-speed steel
Stainless steel
Ball title transmission
Gray finish Drink
Coating cast iron
Dragonfly cast iron
Appendix A
(Informative Appendix)
Common materials for laser ignition workpieces
Chao Ke brand
20.30.35.40,45,50.55,60
16Mn,2CrMnTi.1Cr.50Cr.35CrMn.12CrMa,40CrMnMo.50CrNiG Cr6,GCr9,GCr16,GCr9SiMn,CCr15SiMn65,t5Mn.70Mn.55Si2Mn.50CrVA.55CrMnA.55SiMnVBT7,T8.TEMn,T9,TI0.T11.T12,T139SiCr.CWMn,5CrNiMo.3Cr2W8V,45iCrV,4Cr5MoV1 Si,Cr12MoVW i8Cr1V,W9Cr4V2,W6Ct5Mn-1V2.W12Gr4V4Mn2Crj.3Cr13, 4Cr13, 3Cr13Mo.1Cr17Ni2.9Cr8.2Cr13Ni2.9Cr18MoVGB/T18683—2002
QT400-17.QT450-10,QT500- 7.QT600-3.QT700-2.QT800 2.QT900 2HT200.HT250.HT300.HT350
KTH300-06.KTH$50-10.KTZ450-05.KTZ350-04,KTZ650-02.K12700-02RuT2Go.Rur30a,RuTso.RuT380.RuT420 Note: Under the same laser surface ignition parameters, the maximum hardening degree can be obtained when the original structure is in the annealing state, and its degree is also relatively high. The depth of the hardened layer is the shallowest in the annealing state, and the hardness is lower: therefore, the specific requirements of the material should be selected according to the appropriate preheat treatment. Appendix B
(Normative Appendix)
Microhardness measurement method for the depth and width of the hardened layer When the microhardness method is used to test the depth of the hardened layer, the indentation should be made on a strip or multiple parallel lines perpendicular to the surface of the specimen within a range of a specified width of 0.5 mm centered on the crescent-shaped bottom of the cross section of the hardened layer and the vertical line to the surface (see Figure B1). The distance between the center of the indentation closest to the surface and the surface of the specimen should be approximately twice the length of the indentation diagonal line, and the distance from the surface to the center of each successive indentation should not increase by more than 0.1 mm (e.g. d1~d1≤0.1 mm), and the distance between two adjacent indentations should be not less than 2.5 times the length of the indentation diagonal line. The hardness-depth curve is used to determine the depth of the hardened layer, that is, the distance from the workpiece surface to the measuring point with a hardness value equal to the hardness limit is the effective hardening depth, and the distance from the workpiece surface to the starting point with a hardness value equal to the matrix hardness is the total hardening layer depth. At each site, at least three hardness points should be measured, and the average hardness value should be used as the hardness value of the point. The above principle should also be followed when testing the width of the hardened layer. Unless there is a special agreement between the parties concerned, the load of the hardness test should generally be 0.98N~1.96V. CB/T186832002
Phase transformation zone
Hot purple sound wind
Figure B.1 Schematic diagram of microhardness measurement of depth and width of laser surface quenching hardened layer
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