Technology for reducing cold crack sensibility of X80 pipeline steel welding

Abstract

The invention relates to the technical field of pipeline welding, in particular to a technology for reducing cold crack sensibility of X80 pipeline steel welding. The technology includes the steps of preheating, welding and heat treatment after the welding. A high preheating temperature is adopted for slowing down cooling speed after the welding, which helps diffusible hydrogen in weld joint metal to escape, meanwhile, the quench hardening degree of weld joints and heat affected areas is reduced, and the crack resistance of a welded splice is improved. The heat treatment is performed at once after the welding, high-temperature heating is performed, then slow cooling is performed, and heat preservation is performed so that residual stress after the welding can be eliminated, and the residual hydrogen is prompted to diffuse and escape. Therefore, cold cracks caused by restraint stress and the quench hardening structure can be reduced.

Description

technical field

[0001] The invention relates to the technical field of pipeline welding, in particular to a process for reducing the sensitivity to cold cracking of X80 pipeline steel welding. Background technique

[0002] With the development of the petroleum industry, pipeline transportation of oil and gas has developed rapidly due to its safety, economy and high efficiency. As the pressure of natural gas transportation increases, the steel grade of pipeline steel also increases. X80 pipeline steel has been successfully applied on a small scale in the test section of the West-East Gas Transmission Branch Project, and it is planned to be widely used in the long-distance natural gas pipeline project in the next step. X80 is an ultra-low-carbon, micro-alloyed high-strength steel. It is a pipeline steel material with excellent performance and has a good application prospect. However, because high-grade pipeline steel is quite different from low-grade pipeline steel in terms o...