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采用CO2气体保护焊选择ER55-G焊丝焊接了超细晶Q460钢,研究了焊接接头显微组织、断口形貌以及力学性能。结果表明,焊缝主要由铁素体和少量珠光体构成,焊缝中大量针状铁素体的生成有利于提高焊缝金属的强度和韧性。焊接接头热影响区粗晶区为贝氏体组织,相变重结晶区和不完全重结晶区未出现软化现象。焊缝金属同热影响区冲击断口均为韧窝状韧性断裂,由于超细晶Q460钢材质的高度纯净化以及焊接过程中较小线能量的选择,焊接接头热影响区表现出优异的冲击韧性。
CO2 gas shielded welding was chosen to weld the ultrafine-grained Q460 steel with ER55-G welding wire. The microstructure, fracture morphology and mechanical properties of the welded joint were studied. The results show that the weld is mainly composed of ferrite and a small amount of pearlite. The formation of a large amount of acicular ferrite in the weld helps to improve the strength and toughness of the weld metal. The HAZ of the welded joint is bainite, and the softening phenomenon does not occur in the recrystallization zone and the incomplete recrystallization zone. Weld metal with heat affected zone impact fracture are ductile toughness fracture, due to the ultra-fine grain Q460 steel a high degree of purity and the welding process of small line energy selection, welded joint heat-affected zone showed excellent impact toughness .