Development of Seamless Steel Line pipe in X60 Grade

Relevant problems concerning the production of the X60（PSL1）seamless steel linepipe are discussed in terms of chemical composition,manufacturing process flow and pilot commercial production,and the causes therefore are analyzed.It is identified that at the temperature above 1 050℃,the austenitic gains of the MnNb steel are subjected to significant mixing and coarsening,thus producing negative influence on the comprehensive mechanical properties of the tube,particularly the impact toughness.It is an effective approach to keep the final rolling temperature of the Accu-roll Pipe Mill less than 1 050℃to improve the steel’s impact toughness,which is also a critical step of the non-quench-temper manufacturing process to produce X60（PSL1）seamless steel linepipe.