JB/T 5078-1991 General provisions for material selection and heat treatment quality control of high-speed gears
Some standard content:
Mechanical Industry Standard of the People's Republic of China
JB/T5078--91
Material selection and heat treatment of high-speed gears
General provisions for quality control
Issued on June 11, 1991
Issued by the Ministry of Machinery and Electronics Industry of the People's Republic of China
Implementation on July 1, 1992
Mechanical Industry Standard of the People's Republic of China
Material selection and heat treatment of high-speed gears
General provisions for quality control
1 Subject content and scope of application
JB/T5078-97
This standard specifies the material selection and heat treatment quality control of involute high-speed gears used in turbine generator sets, turbine compressors, blowers, centrifugal pumps, etc.
This standard applies to the control and inspection of gear materials and heat treatment quality when manufacturing high-speed gear devices. 2 Reference standardsbzxz.net
GB1591
GB1979
GB3077
GB4341
GB4342
GB5030
GB5216
GB5617
GB6394
GB9450
ZBJ17001
ZBJ36009
HB5022
Test method for end quenching of steel
Test method for macrostructure and defects of steel by acid etching Test method for Rockwell hardness of metal
Test method for Brinell hardness of metal
Low alloy structural steel||t t||Structural pin low-power structure defect rating chart
Technical conditions for alloy structural steel
Metal Shore hardness test method
Metal microscopic Vickers hardness test method
Metal small load Vickers hardness test method
Technical conditions for structural steel with guaranteed permeability
Determination of effective hardened layer depth after induction quenching or flame quenching of potsMethod for determination of average grain size of metals
Determination and verification of effective hardened layer depth of steel partsCarburizing, ammonia carbon co-painting process and quality control of gearsMetallurgical inspection of induction floating fire of steel parts
Metallurgical inspection of carburized, carbonitriding and ammoniated parts3Basic requirements for quality control
3.1 Principles of material selection
The following contents should be comprehensively considered when selecting high-speed gear materials:3.1.1 Chemical composition, mechanical properties and machinability of materials.3.1.2 The steel grade used should be determined according to the working conditions and heat treatment process (quenching and tempering or surface hardening treatment) of high-speed gears. 3.1.3 For high-speed gears that bear heavy loads and impacts, nickel, chromium, molybdenum steel or nickel steel should be used. 3.1.4 High-speed gears should use structural steel that ensures permeability. 3.1.5 The materials used to manufacture high-speed gears should have high purity and dimensional stability. Approved by the Ministry of Machinery and Electronics Industry on June 11, 1991 and implemented on July 1, 1992
3.1.6 Economic rationality of materials.
3.2 Quality control of raw materials and gears
JB/T5078--91
3.2.1 Raw materials or gears must be accompanied by a certificate of conformity or a quality guarantee. The inspection department is responsible for inspecting their size, appearance and hardness in accordance with the requirements of the purchase order or the drawing, and checking the chemical composition, macrostructure (acid etching, sulfur print, inclusions) hardenability, grain size and mechanical properties of the steel in accordance with the technical requirements.
3.2.2 Raw material inspection sheets or gear inspection records should be submitted to the inspection department and quality management department for filing. 3.2.3 Inexpensive materials or gears that fail the inspection should be marked with "not allowed to use" and stored for processing. 3.2.4 The substitution of raw materials must be signed by the relevant units and approved by the chief engineer or technical deputy director before it can be put into production. 3.2.5 The raw materials for manufacturing high-speed gears must be annealed or normalized to make the structure uniform, the mechanical properties meet the requirements and have good processing performance.
3.2.6 In order to reduce the hardness and improve the processing performance, the gears should be annealed or normalized. 3.3 Pre-heat treatment quality control
33, 1 Carburized high-speed gear teeth should be normalized after carburizing. 3.3.2 Nitrided high-speed gear teeth should be tempered after rough carburizing. During tempering, the tempering temperature should be 10℃ higher than the nitriding temperature, but the minimum tempering temperature should not be lower than 550℃. 3.3.3 Induction quenched high-speed gear teeth must be tempered, and the hardness range of tempering should be 240～340HB. 3.4 Final heat treatment quality control
3.4.1 Carburized quenching
Before gas carburizing quenching, high-speed gears should be subjected to a flash test with a furnace sample. After confirming that the process is feasible, the treatment can be carried out. The test items of the sample are:
a. Use a Vickers hardness tester with a load of 9.8N to measure the effective hardened layer depth in the middle of the test drop. The measurement method is in accordance with GB9450 and GB4342 or GB5030. The test size is as follows: mm
Gear module
Note: 8 is a four-tooth index,
(12~31)
b. Observe the carburized layer structure under a metallographic microscope and grade it according to the provisions of HB5022. The normal microstructure should be a fine tempered martensite matrix with dispersed carbides. Severe carbide networks or large carbide aggregations are not allowed. c. When the carbon concentration distribution curve is required to be determined, the peeling test (diameter 30mm, length 150mm) can be used for determination. If there is no special requirement, the carbon concentration of the top layer of carburized high-speed gears should be between 0.75% and 0.95%. 3.4.2 Induction ignition
3.4.2.1 Before induction ignition, the high-speed gears of new products should be subjected to ignition process tests on the test gears with the selected inductor. First, check whether there are cracks on the surface, then dissect and check the tooth surface hardness, hardened layer depth, uniformity of hardened layer distribution along the tooth corridor and metallographic structure. Only when the above inspection items meet the technical requirements can the high-speed gears be ignited. 3.4.2.2 For old high-speed gears, the first inspection procedure of the ignition process should be adhered to, that is, carburize one tooth first, and the quality inspector shall check its surface cracks, surface hardness and hardened layer distribution. Only after the first inspection is qualified and signed by the inspector can the ignition be carried out. 3.4.3 Nitriding treatment
For nitrided gears, the surface looseness, diffusion layer compound morphology and compound layer thickness should be checked using furnace profiling specimens. 3.5 Requirements for heat treatment equipment and processes
3.5.1 For gas carburizing (or carbonitriding) equipment, the carbon potential should be effectively controlled. JB/T5078-91
3.5.2 In general, the carbon potential should be controlled within the range of 0.75% to 0.95% during the carburizing process. Important high-speed gears should also control the carbon potential through carbon analysis of the sample. The sample size is 30mm in diameter and 150mm in length. The remaining layer from the surface is 0.15, 0.10 and 0.10mm for carbon analysis.
3.5.3 The nitriding process parameters should comprehensively consider the surface state of the high-speed gear, the ammonia decomposition rate, the temperature and the nitriding time. Before nitriding, the oxides or dirt on the surface of the high-speed gear should be removed. 3.5.4 The inductor used for induction fire should ensure that the high-speed gear can obtain the required hardening layer distribution. The shaft fixture should be centered and the maximum eccentricity should be controlled within 0.05mm.
4 Basic requirements for quality inspection
4.1 Quality inspection of raw materials and gear parts
4.1.1 The chemical composition of raw materials shall comply with the provisions of GB3077 and shall be inspected for each furnace. 4.1.2 After rough turning of gear parts, each piece shall be subjected to ultrasonic flaw detection or magnetic particle detection. 4.1.3 The grain size of raw materials shall be inspected and determined for each batch according to the provisions of GB6394. 4.1.4 If the technical conditions have permeability requirements, the test inspection shall be carried out according to GB225. 4.1.5 The hardness of raw materials shall be inspected for each batch according to the order requirements or drawings. 4.1.6 If the technical conditions require mechanical property tests, the test pieces shall be taken from the main material of the gear part, and the mechanical property indicators shall not be lower than the provisions of GB1591 or GB3077.
4.1.7 The macrostructure of raw materials shall be spot-checked for each batch according to the provisions of GB226 and GB1979. 4.2 Quality inspection of pre-heat treatment
4.2.1 After pre-heat treatment (normalizing or quenching and tempering), the Brinell hardness of each gear should be checked according to the drawing. Measure 4 points symmetrically on the tooth surface in the middle of the tooth width without fixing the circumferential direction. For gears with a diameter greater than 2000mm, the number of measuring points should be appropriately increased. If all the hardnesses are qualified, it is considered qualified. The measurement method shall be in accordance with GB23].
4.2.2 For high-speed gears with special requirements in the drawings or contracts, after quenching and tempering or normalizing, the metallographic structure can be checked with the furnace sample. 4.2.3 If there are explicit provisions in the drawings, ultrasonic or magnetic particle testing shall be carried out on the pre-heat treated gears, and mechanical performance tests shall be carried out. The test rod shall be taken from the gear body material. 4.3 Quality inspection after final heat treatment
4.3.1 Tooth surface hardness
4.3.1.1 The tooth surface hardness of each high-speed gear shall be checked according to the requirements of the drawings. 4.3.1.2 The tooth surface hardness shall be measured symmetrically at 4 points along the circumferential direction on the tooth surface in the middle of the tooth width. For gears with a diameter greater than 2000mm, the number of measurement points may be appropriately increased. All qualified hardnesses shall be considered qualified. The measurement method shall be in accordance with GB230 or GB4341. For gears with a tooth width greater than 100mm, the number of measurement points shall be appropriately increased in the tooth width direction. 4.3.1.3 For quenched and tempered high-speed gears, hardness testing is allowed on the end face of the gear teeth, the backing of the herringbone gear, and the parts near the gear teeth of the shaft gear (except the bearing neck).
4.3.2 Effective hardened layer depth
High-speed gears should use furnace profiling specimens to check the effective hardened layer depth of each furnace according to different surface hardening processes, in accordance with GB9450, GB5617 or ZBJ17001. 4.3.3 Metallographic structure of nitrided legs
4.3.3.1 High-speed gears after carbon (or carbonitriding) quenching should use furnace profiling specimens according to the requirements of the drawings and HB5022 to grade carbides, residual austenite and martensite. 4.3.3.2 High-speed gears for gas nitriding should use furnace profiling specimens according to the requirements of the drawings and HB5022 to grade the compound morphology and compound layer thickness of the surface looseness and diffusion layer. 4.3.3.3 High-speed gears for induction nitriding should use furnace profiling specimens according to the requirements of the drawings and ZBJ36009 to grade the martensite of the hardened layer. 4.3.4 Core hardness and core structure
Core hard scrap is inspected by furnace-wound specimens according to the drawing requirements, and the core structure is inspected according to HB5022. 3
4.3.5 Inspection of heat treatment deformation
JB/T5078-91
When the heat treatment process is unstable, the heat treatment deformation disk should be regularly inspected. Measure the tooth shape and tooth direction data before and after the final heat treatment for comparison. The maximum heat treatment deformation should not exceed 50% of the grinding allowance. 4.4 Basic requirements for test results and test reports 4.4.1 Copies of the test results should be submitted to the inspection department and the quality management department for filing. 4.4.2 The test report should indicate the standard number, technical requirements and measured values of the test, and be signed by the inspector and the reviewer. If necessary, the model and measurement accuracy of the test instrument should also be marked. 4.5 Basic requirements for the treatment of unqualified gears All gears that are judged as unqualified products and cannot be repaired after the final inspection shall be labeled as unqualified and stored separately. They are not allowed to be placed with qualified products or recycled products.
Additional instructions:
This standard is proposed and managed by the Zhengzhou Machinery Research Institute of the Ministry of Machinery and Electronics Industry. This standard was drafted by the Zhengzhou Machinery Research Institute. The main drafters of this standard are Wang Xingqin and Xiang Yongjiu.
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