Pipe welding heat treatment process

A process and pipeline technology, applied in the field of pipeline welding heat treatment process, can solve the problems of large structural rigidity, large steel pipe diameter, burning loss of metal alloy elements, etc.

Inactive Publication Date: 2016-06-22
重庆市巴南区仁荣机械厂
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Problems solved by technology

[0002] The steel pipe has a large diameter and a thick wall, so the structural rigidity is large and the restraint stress is large. Therefore, during the welding process, taking measures to prevent cold cracks is a very critical link in the welding of steel pipes. During the welding process, if the welding heat input is too high If the layer temperature is too high, it will lead to the burning of metal alloy elements, and the metallographic transformation of the weld does not meet the requirements, so that the mechanical properties such as impact toughness of the welded joints cannot meet the requirements. Therefore, small specification welding must be used in the welding process, and Strict control of layer temperature

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Embodiment Construction

[0021] Below in conjunction with embodiment the present invention will be further described, and its operating steps are as follows:

[0022] A pipe welding heat treatment process, the process includes the following process requirements:

[0023] (1) Argon arc welding, at an ambient temperature above 0°C, the preheating temperature is 100~150°C;

[0024] (2) During the welding process, the interlayer temperature is 200~300°C;

[0025] (3) After the overall welding of the weld seam is completed, heat treatment should be performed after the weldment is cooled to 100~120°C and kept at a constant temperature for 1~2 hours. When the welded joint cannot be heat treated in time, it should be heated immediately after welding. 250~350℃, heat treatment after constant temperature time, the constant temperature time should be calculated according to the wall thickness of the base metal: calculated as 1h / 25mm, but not less than 4 hours;

[0026] (4) The heating width of the heat treatmen...

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Abstract

The invention discloses a pipe welding heat treatment process. The process is characterized by comprising the following process requirements: conducting argon arc welding with preheating temperature of 100-150 DEG C; keeping an interlayer temperature of 200-300 DEG C in the welding process; cooling a weld joint to 100-120 DEG C, and keeping the constant temperature for 1-2 h, and then conducting heat treatment with uniform temperature at inner and outer walls and on both sides of the weld joint, wherein the heating and cooling rate in the heat treatment is calculated by 6250 / wall thickness DEG C / h, and is not more than 300 DEG C / h; keeping the most constant temperature for heat treatment after welding of the welded joint 20 DEG C-30 DEG C lower than the lowest AC1 temperature among the base metals on both sides and weld joint molten metal; and keeping the temperature difference between any two points on a welding heat treatment constant pressure bearing pipeline at less than 50 DEG C. The pipe welding heat treatment process of the present invention strictly controls process parameters of all stages to improve the mechanical properties of the pipe after welding.

Description

technical field [0001] The invention belongs to the field of heat treatment technology, in particular to a pipeline welding heat treatment technology. Background technique [0002] The steel pipe has a large diameter and a thick wall, so the structural rigidity is large and the restraint stress is large. Therefore, during the welding process, taking measures to prevent cold cracks is a very critical link in the welding of steel pipes. During the welding process, if the welding heat input is too high If the layer temperature is too high, it will lead to the burning of metal alloy elements, and the metallographic transformation of the weld does not meet the requirements, so that the mechanical properties such as impact toughness of the welded joints cannot meet the requirements. Therefore, small specification welding must be used in the welding process, and The layer temperature is strictly controlled. Contents of the invention [0003] In view of the deficiencies in the pr...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C21D9/50
Inventor 李仁荣
Owner 重庆市巴南区仁荣机械厂
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