摘要
This paper introduces mechanical and metallurgical properties of 27mm thick Grade X80 high strain line pipe steel which aims at constructing long distance natural gas over permafrost and seismic areas.The steel is molybdenum and boron free.Dual phase of the X80 steel plates are regulated by thermal-mechanical controlled processing.The outer diameter of 1219mm pipes are manufactured by UOE process.DWTT toughness and longitudinal tensile properties including the Rt0.5/Rm,Rt1.5/Rt0.5 and Rt2.0/Rt1.0 are analyzed on both the plates and the pipes.Strain aging properties are also evaluated on the base material of the pipe,demonstrating that the pipe complies well with the pipeline construction requirements.Strengthening effects of precipitates are analyzed,revealing a 58.1MPa strengthening contribution by precipitates less than 20nm in size.Dislocation hardening is approximately 176MPa in the present studied steel.
