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采用熔化极气体保护焊对电力结构用Q460钢进行不同热输入的对接焊试验。利用金相显微镜、透射电镜和电子背散射衍射技术研究热输入对焊缝组织及冲击性能的影响。结果表明:3种热输入焊缝金属组织均为先共析铁素体、侧板条铁素体和针状铁素体及M-A组元。随着热输入的增加,焊缝组织中板条粗化,而先共析铁素体和侧板条铁素体增多,针状铁素体减少,M-A组元尺寸增大;焊缝金属中大角度晶界含量逐渐减少分别为0.54、0.40和0.37。尺寸较大的M-A组元及大角度晶界密度的降低是导致焊缝金属冲击吸收能量逐渐降低的主要原因。
The use of melting gas shielding welding on the power structure of Q460 steel with different heat input butt welding test. The effects of heat input on the microstructure and impact properties of the weld were investigated by metallographic microscope, transmission electron microscopy and electron backscatter diffraction. The results show that all three heat input weld metal structures are pro-eutectoid ferrite, side-strip ferrite, acicular ferrite and M-A component. With the increase of heat input, the slab in the weld bead coarsens, while the ferrite in the pro-eutectoid ferrite and the side strip increases, the acicular ferrite decreases, and the size of the MA element increases. In the weld metal Large-angle grain boundaries gradually reduce the content of 0.54,0.40 and 0.37. The larger size of the M-A component and the reduction of the high-angle grain boundary density are the main reasons for the gradual decrease of the impact energy absorbed by the weld metal.