焊后热处理对海洋平台用高强度管线钢接头组织和性能的影响

Effect of PWHT on Microstructure and Mechanical Properties of Welded Joints of High Strength Pipeline Steel for Offshore Platform

采用不同的回火时间对海洋平台用ASTM4130钢管对接接头进行焊后回火处理,对焊接接头显微组织进行了观察,并对接头拉伸、弯曲、冲击、硬度等力学性能进行了检测。结果表明,焊缝回火组织主要为针状铁素体+块状铁素体+先共析铁素体,随着回火时间的增加,针状铁素体含量逐渐减少,块状铁素体含量增大,碳化物逐渐析出,晶粒逐渐均匀化;HAZ粗晶区组织逐渐均匀化,马氏体和铁素体含量减少,上贝氏体组织增加,HAZ细晶区和临界区组织无明显变化;随着保温时间的延长,焊缝金属冲击韧性逐渐升高,熔合线冲击韧性则逐渐下降,HAZ冲击韧性先升高后略有降低,母材冲击韧性几乎不受影响;热影响区硬度明显降低,焊缝区硬度则先略有降低后几乎保持不变。

The welded joints of ASTM4130 steel pipe for offshore platform was tempered with different holding time. The microstructure of the welded joint was observed, and the mechanical tensile, bending, impact, hardness and other properties were tested. The results show that the weld microstrueture is mainly acicular ferrite, granular ferrite and proeutectoid ferrite; with the increase of the holding time, acicular ferrite content decreases, granular ferrite content increases gradually, the carbide precipitates and the grain homogenizes gradually. CGHAZ microstructure homogenizes gradually, the martensite and ferrite content decrease, upper bainite content increases, then ,the microstructure of FGHAZ and ICHAZ has no obvious change. With the prolongation of holding time, the impact toughness of weld metal increases, the impact toughness of fusion line decreases, the impact toughness of HAZ first increases and then decreases slightly, and the matrix material impact toughness is almost not affected. The heat affected zone hardness decreases. The hardness in the weld zone first decreases slightly and then almost remains unchanged.