超细晶Q460钢CO2气体保护焊焊接接头组织与性能

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。

Microstructure and properties of CO2 gas metal arc welded joint of ultrafine-grained Q460 steel

Ultra-fine grained Q460 steel was welded by means of CO2 gas metal arc welding using ER55-G electrode.Microstructure,fractograph and mechanical properties of the welded joint were investigated.The results show that the weld metal consists of ferrite and small amount of pearlite.The presence of acicular ferrite in weld metal is beneficial to its strength and toughness.Coarse grain heat affected zone of the welded joint is made up of bainite and softening phenomena is not detected in the grain refined region and transition zone.Fractographs of the weld metal and heat affected zone indicates ductile fracture with the presence of dimples.Due to the high purity of the ultrafine-grained Q460 steel and the selection of relatively lower heat input during the welding process,the heat affected zone exhibits superior impact toughness.