热输入对F69A4-ECM4-M4金属芯埋弧焊丝熔敷金属组织和力学性能的影响

Effect of heat input on microstructure and impact toughness of on F69A4-ECM4-M4 metal-cored submerged arc welding wire deposited metal

采用F69A4-ECM4-M4金属芯埋弧焊丝在不同的热输入(18.67,20.57,22.56,24.63 k J/cm)下焊接熔敷金属,并通过光学显微镜和扫描电镜对其组织进行了观察分析,采取冲击试验方法测试冲击韧性.结果表明,不同热输入的熔敷金属其组织形态和数量也有着明显的差异;随着热输入的增加,其熔敷金属中柱状晶的宽度逐渐增大,-40℃的冲击韧性逐渐降低,断口形貌中放射区比例逐渐增加.当热输入为18.67 k J/cm时,熔敷金属显微组织主要由细小的针状铁素体组成,冲击吸收功达到最大值139 J.随着热输入的增加,熔敷金属高温停留时间长,熔敷金属组织中针状铁素体晶粒急聚长大,从而导致熔敷金属冲击韧性的下降.

Deposited metals were submerged arc welded with F69 A4-ECM4-M4 metal-cored wire under different heat inputs 18. 67,20. 57,22. 56,24. 63 kJ/cm,respectively. Their microstructure and impact toughness were investigated by optical microscope,scanning electron microscope and impact testing.Results showed that the morphology of microstructure and their percentage of deposited metal had significant differences under different heat inputs. With the increase of heat input,the width of columnar crystal of deposited metal increased,impact toughness at-40 ℃ decreased,and radical zone ratio of fracture surface increased. When heat input was 18. 67 kJ/cm,microstructure consisted mainly of fine acicular ferrite,impact absorbed energy reached the maximum value 139 J. The reason of decrease of impact toughness was that deposited metal stayed longer at high temperature,thus acicular ferrite grains grew bigger quickly with the increase of heat input.