Research On The Weldability Of X90 Pipeline Steel

This paper utilizes the combination of welding thermal simulation and welding procedure certification to evaluate the weldability of X90 pipeline steel.Main tasks of this paper are as follows:?1?The SH-CCT curve of X90 pipeline steel was plotted by Gleeble-3500 thermal simulation test machine,and the microstructure changing rule of the continuous cooling transformation of X90 pipeline steel was studied.?2?The change of impact toughness and hardness of X90 pipeline steel with different t_8/5/5 were studied by welding thermal simulation method,the result of which could provide the basis for making proper welding process parameters.?3?The softening phenomenon of the heat affected zone of X90pipeline steel was studied,and the softening temperature was determined.?4?Using SMAW and semi-automatic welding with welding materials of different grades and types,four kinds of welding process schemes were got.According to the API1104 standard,the microstructures and properties of the welded joints were analyzed to evaluate the weldability of X90pipeline steel.And the paper has developed the recommended process file of X90 pipeline girth welding,according to the test results.The research results of this paper can provide the engineering accumulation and technical basis for the development of X90 pipeline steel and the application of X90 pipeline steel in the actual pipeline construction in the future.