Post-weld heat treatment method for u71mnh rail welded joints

A technology of post-weld heat treatment and welded joints, which is applied in the field of rail welding, can solve the problems of low hardness of welded joints, achieve improved performance status, good promotion and application prospects, and normal organizational shape
CN109022749BActive Publication Date: 2020-06-02PANZHIHUA IRON & STEEL RES INST OF PANGANG GROUP
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Patent Information

Authority / Receiving Office
CN · China
Patent Type
Patents(China)
Current Assignee / Owner
PANZHIHUA IRON & STEEL RES INST OF PANGANG GROUP
Publication Date
2020-06-02

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Abstract

The invention relates to a post-welding heat treatment method of U71MnH rail welded joints, and belongs to the technical field of rail welding. The post-welding heat treatment method of the U71MnH rail welded joints aims at solving the problem that the hardness of the joints is affected by harmful tissues such as martensite generated due to the local cooling speed being higher than the critical transition temperature when existing rail welded joints are cooled in the heat treatment process. The post-welding heat treatment method of the U71MnH rail welded joints comprises the following steps ofheating welding seam areas of the U71MnH rail welded joints cooled to below 300 DEG C after being welded to 865-925 DEG C, stopping heating, adopting air spraying for cooling, stopping air spraying for cooling after the temperature of the tread surfaces of the rail joints drops to 458-475 DEG C, and naturally cooling to room temperature. According to the post-welding heat treatment method of theU71MnH rail welded joints, the hardness of the U71MnH rail welded joints is effectively controlled, and meanwhile, normal tissues of the joints is ensured.
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Description

technical field

[0001] The invention belongs to the technical field of rail welding, and in particular relates to a post-weld heat treatment method for U71MnH rail welding joints. Background technique

[0002] Rail welding has the characteristics of high heating temperature, fast heating speed, short residence time at high temperature, uneven temperature distribution and continuous cooling under air-cooling conditions. In the joints, especially in the heat-affected zone, it is easy to have a coarse structure, and even easy to form martensite, shellfish, etc. At the same time, the joints after welding generate internal stress, and under the action of complex external stress, they are prone to fracture and become a weak link in line operation. In order to release the stress, refine the grain, change the microstructure of the joint, and improve the degraded performance state, it is necessary to perform post-weld heat treatment on the rail joint.

[0003] Patent document CN1081...

Claims

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