热输入对高钼Q420钢焊接接头组织和性能的影响

Effect of heat input on microstructure and properties of high molybdenum Q420 welded joint

通过拉伸实验、硬度试验、冲击试验和组织观察研究热输入对高钼Q420钢CO2气体保护焊焊接接头组织与性能的影响,借助Image Pro-Plus 6.0软件测量了焊缝中先共析铁素体、侧板条铁素体和针状铁素体的体积分数比例。结果表明：随着焊接热输入的增加,先共析铁素体和侧板条铁素体组织的含量均逐渐减少,针状铁素体逐渐增加;当焊接热输入为11.68 k J·cm^-1时,针状铁素体体积分数达到最大值81.31%。随着针状铁素体体积分数的增加,焊缝金属的低温冲击韧性增加。

Effects of heat input on microstructure and properties of CO2 gas shielded welded joints of high-molybdenum Q420 steel were investigated by means of tensile test,hardness test,impact test and structure observasion. The volume fraction of the pro-eutectoid ferrite,side lath ferrite and acicular ferrite in the weld seam was measured by Image Pro-Plus 6. 0 software. The results show that with the increasing of the heat input,the content of the pro-eutectoid ferrite and side lath ferrite decreases and the content of the acicular ferrite increases gradually. When the welding heat input is 11. 68 k J·cm^-1,the volume fraction of the acicular ferrite reaches the maximum value of 81. 31%. With the increasing of volume fraction of the acicular ferrite,the low temperature impact toughness of the weld seam metal increases.