CAJ | 학술논문

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。
채용단면량층오겁아호한공예한접2219-T8려합금。접두횡향랍신시단렬발생재부분용화구(PMZ)。침대PMZ조직대접두랍신단렬행위적영향진행계통연구。PMZ중고근용합선적위치정계공정교련속，수착거리용합선거리적증가，정계공정적련속정도축점강저。단구형모화접두현미경도분포표명 PMZ 시일충제도재료。기제도변화적역학성능대접두적단렬행위유중요영향。연구발현，렬문재고근정면한지적 PMZ 계렬，계렬후연원리용합선적방향확전，당렬문첨단확전도소성교호적 PMZ 시，렬문첨단둔화，수후접두여하부분이전절형식발생단렬。
2219-T8 aluminum alloys were butt welded by the double-pass tungsten inert gas (TIG) arc welding process. The transverse tensile test of the joint showed that the fracture mainly occurred in the partially melted zone (PMZ). Effects of the PMZ on the fracture behavior were systematically studied. Continuous intergranular eutectics were observed in the PMZ close to the fusion line. Away from the fusion line, the intergranular eutectics in the PMZ became discontinuous. The fracture morphology and the microhardness distribution of the joint showed that the PMZ was gradient material with different mechanical properties, which strongly affected the fracture process. It was observed that the crack initiated in the PMZ near the front weld toe, and propagated in the PMZ away from the fusion line. Then, the crack tip was blunt when it propagated into the PMZ with higher plasticity. Finally, the rest part of the joint was shear fractured.