以自制自保护药芯焊丝为焊接材料, 采用单面焊双面成形技术在三种热输入下焊接了X80管线钢板, 研究了焊接热输入对接头显微组织和力学性能的影响。结果表明: 随着焊接热输入的增大, 焊缝区针状铁素体量减少, 热影响区的显微组织由贝氏体铁素体和粒状贝氏体转变为准多边形铁素体和多边形铁素体; 随着焊接热输入的减小, 焊缝区和热影响区试样的冲击吸收功均增大, 冲击断裂方式由准解理或解理型的脆性断裂向韧窝型的韧性断裂转变; 焊缝区和热影响区的硬度低于母材的, 且热影响区的硬度略低于焊缝区的, 随着热输入的增大, 焊接接头的硬度整体有所下降。

With self-made self-shielded flux-cored wire as welding material, the X80 pipeline steel plate was welded with three heat input by one-side welding with back formation technique. The effects of the welding heat input on the microstructure and mechanical properties of the welded joint were studied. The results show that with the increase of the heat input, the amount of acicular ferrite in the weld zone decreased and the microstructure of the heat affected zone transformed from bainite ferrite and granular bainite into quasi-polygonal ferrite and polygonal ferrite. The impact energy of the weld zone and heat affected zone samples both increased with the decrease of the heat input and the impact fracture mode changed from brittle fracture with the typical quasi-cleavage or cleavage characteristics to ductile fracture with the dimple characteristic. The hardness of the weld zone and heat affected zone was both lower than that of the base metal and the hardness of the heat affected zone was lower than that of the weld zone. With the increase of heat input, the overall hardness of the welded joint decreased.