通过夏比冲击试验和组织观察,研究了X80管线钢焊接热影响区不同区域的韧性分布及其原因。结果表明,焊接峰值温度低于950℃时,韧性变化不大;当峰值温度达到1300℃时,X80管线钢所对应的粗晶热影响区韧性最低,形成了局部脆化区域。引起粗晶热影响区韧性降低的原因为晶粒的显著长大和粗大M-A岛状组织的形成。 Through the Charpy impact test and microstructure observation, the toughness distribution and its causes in different regions of HAZ of X80 pipeline steel were studied. The results show that the toughness changes little when the welding peak temperature is lower than 950 ℃. When the peak temperature reaches 1300 ℃, the toughness of the coarse grain heat affected zone (XRD) corresponding to X80 pipeline steel is the lowest, forming the local embrittlement zone. The reason for the decreased toughness of the coarse heat-affected zone is the remarkable growth of grains and the formation of coarse M-A island tissue.