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Heat treatment method for carrying out isothermal annealing on railway vehicle axle in advance

A heat treatment method and isothermal annealing technology, used in heat treatment furnaces, heat treatment equipment, furnaces, etc., can solve the problems of uneven microstructure, mixed crystals, grain size difference, etc., to achieve uniform microstructure and reduce grain size. Unqualified, fatigue fracture prevention effect

Pending Publication Date: 2016-08-24
MAANSHAN IRON & STEEL CO LTD
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  • Application Information

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Problems solved by technology

[0008] To sum up, at present, medium-carbon steel or medium-carbon low-alloy steel road vehicle axles at home and abroad generally adopt the process of normalizing twice + tempering once, and the main problem is that the microstructure often appears very uneven after heat treatment , That is, mixed crystal phenomenon, according to GB / T6394 or ASTM E112 standard detection (take the sample at the 1 / 2 radius of the axle), the grain size difference can reach 2-4

Method used

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  • Heat treatment method for carrying out isothermal annealing on railway vehicle axle in advance
  • Heat treatment method for carrying out isothermal annealing on railway vehicle axle in advance
  • Heat treatment method for carrying out isothermal annealing on railway vehicle axle in advance

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Embodiment 1

[0033] A heat treatment method for pre-isothermal annealing of a railway vehicle axle, comprising the following steps:

[0034] (1) Isothermally anneal the axle of the railway vehicle, heat it to the holding temperature of the first stage at 800±10°C, the holding time is 3.5-4.5 hours, and air cool to the holding temperature of the second stage at 620±10°C, and the holding time is 2.5-3.5 hours , followed by air cooling;

[0035] (2) normalizing the railway vehicle axle after step (1), the holding temperature is 790 ± 10 ℃, and the holding time is 3.5-4.5 hours; cooling in the air of accelerated flow;

[0036] (3) Tempering the railway vehicle axle after the treatment in step (2), the tempering holding temperature is 510±10° C., the holding time is 3.5-4.5 hours, and the obtained railway vehicle axle has a grain size of 7-8.

[0037] The heat treatment method of the isothermal annealing adopted in embodiment 2-8 and the parameter control, grain size and mechanical properties ...

Embodiment 4

[0043] The grain size of Example 4 is grade 9, while that of Comparative Example 2 is grade 5-7. Obviously, the grain size fluctuation of Example 4 is smaller and the grains are finer.

Embodiment 5

[0044] The grain size of Example 5 is grade 7, while that of Comparative Example 3 is grade 4-7. Obviously, the grain size fluctuation of Example 5 is smaller and the grains are finer.

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Abstract

The invention discloses a heat treatment method for carrying out isothermal annealing on a railway vehicle axle in advance. The heat treatment method comprises the following steps that 1, isothermal annealing is carried out on the railway vehicle axle in advance; 2, the railway vehicle axle treated in the step 1 is subjected to normalizing one time or two times; 3, the railway vehicle axle treated in the step 2 is subjected to tempering. Compared with the prior art, the microscopic structure of the axle is uniform and tiny, the bad phenomena of grain size disqualification and ultrasonic flaw detection acoustic transmission caused when the open grain structure appears can be reduced, and fatigue crack caused by mixed crystals is prevented.

Description

technical field [0001] The invention relates to a heat treatment process for steel, in particular to a heat treatment method for pre-isothermal annealing of a railway vehicle axle. Background technique [0002] Railway vehicle axle steel is an important part to ensure the safety of railway vehicles. During the operation of railway vehicles, the bearings are subjected to bending force, torsional force and impact force, and they are used under alternating stress conditions for a long time, so the stress situation is very complicated. In order to ensure the quality of railway vehicle axle steel, especially to prevent the fatigue fracture of the axle during use, it is very important to adopt a reasonable and appropriate heat treatment process to obtain a uniform and fine microstructure of the axle. [0003] The Chinese industry standard TB / T2945-1999 "Technical Conditions for LZ50 Steel Axles and Steel Billets for Railway Vehicles" stipulates that the heat treatment process of c...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C21D9/28C21D1/26C21D1/28
CPCC21D1/26C21D1/28C21D9/28
Inventor 完颜卫国王民章许兴谭凌胡芳忠龚志翔
Owner MAANSHAN IRON & STEEL CO LTD
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