Material design for line pipe steel to minimize HAZ softening and to obtain good HAZ toughness

摘要

In order to develop a material design concept for strain based design, effect of HAZ softening on deformation behavior was studied by FE analysis. To control the HAZ softening and hardening, effect of chemistry on hardness in HAZ was evaluated by the taper hardness test. A UOE pipe of X80 with low carbon content of 0.05mass%, adequate Pcm value of 0.20mass% and high Ceq(IIW) of 0.50mass% was produced and its properties were evaluated