不同热输入条件下X100管线钢焊接热影响区的组织和冲击韧性

Microstructure and Impact Toughness of Heat Affected Zone of X100 Pipeline Steel under Different Welding Heat Input Conditions

采用热模拟技术,对X100管线钢在不同焊接热输入和二次热循环峰值温度下热影响区的组织与冲击韧性进行了研究。结果表明:单道次焊接热输入为15 kJ·cm^(-1)时,热影响区组织以板条贝氏体为主,具有优异的冲击韧性;而热输入为25 kJ·cm^(-1)时,以粒状贝氏体组织为主,其韧性明显恶化;双道次焊接热输入为15 kJ·cm^(-1)、二次热循环峰值温度为600℃时,热影响区具有良好的冲击韧性,但随二次热循环峰值温度升高,热影响区组织均为粗大的粒状贝氏体,其冲击韧性显著降低;焊接热输入为25 kJ·cm^(-1)时,热影响区组织均以粒状贝氏体为主,其冲击韧性均非常差。

The microstructure and impact toughness of heat-affected zone （HAZ） of X100 pipeline steel under the conditions of different welding heat inputs and secondary heat cycle peak temperature were studied by welding thermal simulation. The results show that the mierostructure of HAZ mainly composed of lath bainite when one cycle welding heat input was 15kJ·cm-1 , and the microstructure of HAZ had excellent impact toughness. When the heat input was 25 kJ·cm-1 the microstructure of HAZ mainly consisted of granular bainite and impact toughness drastically decreased. For two cycles welding, the HAZ had good impact toughness when the welding heat input was 15 kJ·cm-1 and secondary heat cycle peak temperature was 600 ℃. However, the microstructure of HAZ were coarse granular hainite with the increase of secondary heat cycle peak temperature, and the impact toughness quickly reduced. When the heat input was 25 kJ·cm-1, the impact toughness was very poor Because the microstructure of HAZ was mainly granular bainite.