焊接工艺对TP304/SS400异种钢焊接接头组织和性能的影响

利用扫描电子显微镜并通过常温拉伸弯曲、低温冲击以及显微硬度等试验研究了FCAW，SMAW和GTAW三种不同的焊接工艺对TP304/SS400异种钢焊接接头组织和性能的影响. 结果表明，三种焊接工艺条件下，焊缝金相组织都为δ铁素体+奥氏体，但δ铁素体含量及形态分布有明显差异；FCAW焊缝中蠕虫状δ铁素体和GTAW焊缝中针状δ铁素体可有效提高韧性，故冲击韧性较高，SMAW焊缝中骨骼状δ铁素体对韧性不利，冲击韧性最低，且随冲击吸收能量的降低断口由韧性断裂转变为脆性断裂；三种焊接工艺条件下，焊接接头综合力学性能表现良好，整体显微硬度值变化不大.

Study of microstructure and properties of TP304/SS400 dissimilar welding joints under three processes

The joining of dissimilar materials of TP304 austenitic stainless steel and SS400 mild steel was performed using flux-cored arc welding (FCAW), shielded metal arc welding (SMAW) and gas tungsten arc welding (GTAW) methods. The microstructure and mechanical properties of welding joints of TP304 and SS400 were investigated by scanning electron microscopy (SEM) and multi-tests, such as micro-hardness test, tensile test, bend test and impact toughness test. The results indicate that the microstructure in weld metal zone is a mixture of δ-ferrite and austenite, but the content and morphology of δ-ferrite are significantly different. Both the vermicular δ-ferrite in FCAW welds and the acicular δ-ferrite in GTAW welds can improve the toughness effectively, but the impact absorbing energy in SMAW welds decreases for skeletal distribution of δ-ferrite. The impact fracture changed from ductile features to brittle features with the decrease of impact absorbed energy. The mechanical properties of welded joints were excellent and the micro hardness is relatively stable.