Research on CCT Curve of X70 Pipeline Steel

The law of phase change of X70 pipeline steel during continual cooling was studied by Gleeble 1500.The CCT curves of X70 pipeline steel were drawn by adopting dilatometer and metallographic method,and the effects of cooling rates on microstructure and hardness of the steel were studied.The experimental results show that the microstructure of the steel are mainly Ferrite,Perlite and Bainites.With the increase of cooling rate,the phase transition temperature of tested steel decreases.With the increase of deforming degree,the phase transition temperature of tested steel increases slightly as in the same cooling rate.