Crack test and maximum hardness test of inclined single-V groove with broad root face is performed by using BOHLER E9010 G electrode

and the cold crack susceptibility of X80 pipeline steel is investigated based on microstructure analysis and residual stress analysis. Results show that X80 pipeline steel is sensitive to cold crack without preheating

and preheating can effectively reduce the cold susceptibility of X80 pipeline steel and the magnitude of equivalent residual stress of joints. The cross-sectional crack rate is the lowest with preheating temperature of 150 ℃. However

when preheating temperature is more than 150 ℃

the cold crack susceptibility increases since the microstructure of coarse grained region becomes coarse

and the magnitude of transverse residual stress and equivalent residual stress of joint increase.