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采用单面两层钨极氩弧焊工艺焊接2219-T8铝合金。接头横向拉伸时断裂发生在部分熔化区(PMZ)。针对PMZ组织对接头拉伸断裂行为的影响进行系统研究。PMZ中靠近熔合线的位置晶界共晶较连续,随着距离熔合线距离的增加,晶界共晶的连续程度逐渐降低。断口形貌和接头显微硬度分布表明PMZ是一种梯度材料。其梯度变化的力学性能对接头的断裂行为有重要影响。研究发现,裂纹在靠近正面焊趾的PMZ启裂,启裂后沿远离熔合线的方向扩展,当裂纹尖端扩展到塑性较好的PMZ时,裂纹尖端钝化,随后接头余下部分以剪切形式发生断裂。
Using single-sided two-layer TIG welding process 2219-T8 aluminum alloy. Fracture occurs in the partial melting zone (PMZ) when the joint is stretched transversely. A systematic study was conducted on the effect of PMZ on tensile fracture behavior of joints. In the PMZ, the grain boundary eutectic is more continuous near the fusion line, and as the distance from the fusion line increases, the continuous degree of grain boundary eutectic gradually decreases. Fracture morphology and microhardness distribution of the joints indicate that PMZ is a gradient material. The mechanical properties of the gradient changes have an important impact on the fracture behavior of joints. It is found that the cracks crack in the PMZ close to the front toe and then extend away from the fusion line after cracking. When the crack tip extends to the ductile PMZ, the crack tip is passivated, and then the rest of the joint is cut in the form of shear Fracture occurred.