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Railway vehicle axle heat-treatment technology for full pre-annealing by use of residual forging heat

A complete annealing technology for railway vehicles, applied in heat treatment furnaces, heat treatment equipment, manufacturing tools, etc., can solve problems that are difficult to eliminate, achieve the effects of reducing unqualified grain size, reducing production costs, and preventing fatigue fracture of axles

Inactive Publication Date: 2016-11-30
MAANSHAN IRON & STEEL CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

This kind of coarse grain is hereditary, and it is difficult to eliminate it after the usual two-time normalizing and one-time tempering heat treatment process

Method used

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  • Railway vehicle axle heat-treatment technology for full pre-annealing by use of residual forging heat
  • Railway vehicle axle heat-treatment technology for full pre-annealing by use of residual forging heat
  • Railway vehicle axle heat-treatment technology for full pre-annealing by use of residual forging heat

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0025] A heat treatment process for a railway vehicle axle that utilizes forging waste heat to carry out complete annealing in advance, comprising the following steps:

[0026] (1) When the axle steel of railway vehicles is forged, the final forging temperature is ≥750°C. After the final forging, the axle is placed in a heat treatment furnace at 790±10°C for complete annealing, and cooled to 400°C with the furnace at 30-40°C / h The following are out of the oven and air-cooled.

[0027] (2) Normalize the axle after complete annealing in step (1) at 810°C±10°C, and keep it warm for 3-3.5 hours.

[0028] (3) Temper the axle after normalizing in step (1) at 510°C±10°C, and keep it warm for 4-4.5 hours.

Embodiment 2-10

[0029] Embodiment 2-10, comparative example 1-3

[0030] See Table 1 for the specific treatment process, grain size and mechanical performance test results of the axles of Examples 2-10 and Comparative Examples 1-3.

[0031] Other quality inspection results of the embodiment all meet the requirements of corresponding product standards. The grain size sample is taken at the 1 / 2 radius of the axle. The grain size of LZ50 and LZ45CrV is tested according to GB / T6394 standard, and the grain size of AAR F is tested according to ASTME112G standard. See Table 1 for the grain size and mechanical performance test results of the axles of Examples 1-10 and Comparative Examples 1-3.

[0032] Grain size, mechanical property test result of table 1 embodiment 1-10 and comparative example 1-3 axle

[0033]

[0034]

[0035] continued

[0036]

[0037] *Final forging (rolling) temperature ≥ 750 ℃.

[0038] **Normalizing holding time for follow-up heat treatment is 3-3.5 hours, and ...

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Abstract

The invention discloses a railway vehicle axle heat-treatment technology for full pre-annealing by the use of residual forging heat. In comparison with the prior art, the invention is characterized in that full annealing is carried out by the use of residual thermal forming heat so as to let the vehicle axle obtain a microscopic structure which is close to the equilibrium state and make a structural preparation for subsequent heat treatment of the vehicle axle. Thus, the microscopic structure of the vehicle axle can be obviously made to be uniform and fine after conventional ''two normalizing and one tempering'' or ''one normalizing and one tempering''. Sampling is carried out at the 1 / 2 radius of the vehicle axle, and detection is carried out according to the GB / T6394 or ASTM E112 standard. Then, grain size difference can be controlled to be less than or equal to Grade 1.5, and grain size difference of 90% products can be controlled to be less than or equal to Grade 1.0. The microscopic structure of the vehicle axle is uniform and fine, and ultrasonic flaw detection disqualification caused by coarse microscopic structure is avoided and fatigue fracture resistance of the vehicle axle is enhanced. By the use of residual forging heat for heat treatment, energy can be saved and production cost is reduced.

Description

technical field [0001] The invention relates to the technical field of steel heat treatment, in particular to a heat treatment process for railway vehicle axles which utilizes forging waste heat to perform pre-complete annealing. Background technique [0002] At present, domestic railway vehicle axle steel manufacturers generally select steel billets for forging according to the axle shaft type and size, and the axles are generally cooled in the air after forging. The Chinese industry standard TB / T2945-1999 "Technical Conditions for LZ50 Steel Axles and Steel Billets for Railway Vehicles" stipulates that after forging, the axles should be cooled to below 500°C before further heat treatment. At present, the heat treatment process commonly used for medium-carbon or medium-carbon low-alloy steel axles is two times of normalizing and one time of tempering. [0003] Due to the small compression ratio, smaller local compression ratio, uneven surface and internal deformation, and ...

Claims

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Application Information

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IPC IPC(8): C21D1/28C21D9/28
CPCC21D1/28C21D9/28
Inventor 完颜卫国龚志翔胡芳忠
Owner MAANSHAN IRON & STEEL CO LTD
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