Microstructure evolution and corrosion resistance in simulated CGHAZ of X80 high-deformability pipeline steel

In this study,the microstructure evolution and corrosion resistance in 0.5 M Na₂CO₃-1 M NaHCO₃ solution of X80 high-deformability（X80HD） pipeline steel coarse-grained heat-affected zone（CGHAZ） with several heat input levels were investigated.It is shown that the microstructure of CGHAZ changes from bainite ferrite to granular bainite as the heat input increasing.In addition,the corrosion resistance and the stability of passive film of base material are better than those of CGHAZ with several heat input levels.Too small or too big heat input is inadvisable and better corrosion resistance of CGHAZ is attained when heat input is 30 kJ/cm.