Pipe welding heat treatment process

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...

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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