焊接线能量对WELDOX960超强精细低合金钢焊接接头组织和力学性能的影响

Effects of Welding Heat Input on Microstructure and Mechanical Properties of Welded Joint of WELDOX960 High-strength Fine Low-alloyed Steel

根据"等强匹配"原则,选取ED-FK1000实心镀铜焊丝对WELDOX960钢进行焊接,通过拉伸、弯曲、硬度和冲击试验,研究了不同焊接线能量对该钢焊接接头力学性能的影响,采用光学显微镜和扫描电镜对接头组织和断裂形貌做了进一步分析。结果表明,在焊接热循环的作用下,WELDOX960焊接热影响区是整个接头的薄弱环节,当焊接线能量较大时,在热影响区产生晶粒粗化,出现上贝氏体和局部区域软化等问题,使接头强度急剧下降。严格控制焊接线能量是该钢焊接的关键因素。

ED-FK1000 copper-plating solid wire was selected as filling material to weld WELDOX960. The effects of different heat input on mechanical properties of the welded joints were studied by tests of tension, bending, hardness and impact, and the microstructure and fracture morphology of the joint were observed by optical microscopy and scanning electron microscopy. The results show that the HAZ is the weakest part of the joint under the effect of welding thermal cycle. When the welding energy is big, the grains in the HAZ coarsen, and the joint strength declines dramatically with the formation of upper bainite and local softening area. Strict control of heat input is the key factor in the welding of WELDOX960 steel.