In order to strengthen the quality control of high performance steel pipe

the chemical composition

mechanical properties and metallographic microstructure of X90 straight seam pipe produced by 10 major domestic steel pipe plants are analyzed in detail. The performance control of X90 straight seam pipe is analyzed

and the control degrees of each element of chemical composition

tensile properties

impact properties and hardness are ranked. At the same time

the problems of X90 straight seam pipe are analyzed from two aspects of performance and welding embitterment

and the corresponding cause analysis and treatment direction are provided. The results show that the control of the chemical components of Nb+V+Ti

P

CEpcm and Mn should be strengthened. The control degree ranking of tensile property is elongation >tensile strength > yield strength

and special attention should be paid to the control of yield ratio. The control degree ranking of average impact energy is base metal transverse control > heat affected zone transverse control > weld transverse control. But the control degree ranking of standard deviation of impact energy is weld transverse control > base metal transverse control > heat affected zone transverse control. PF in the fusion zone of metallographic microstructure accounts for a large proportion

which is the main cause of softening and should be paid close attention to.