9Cr-1.5W-0.15Ta耐热钢电子束焊缝和搅拌摩擦焊缝组织性能比较

对9Cr-1.5W-0.15Ta耐热钢分别进行电子束焊和搅拌摩擦焊工艺试验，研究了不同焊接方法对焊缝微观组织及接头冲击韧性的影响规律. 结果表明，电子束焊缝由粗大的树枝状板条马氏体组成，且原奥氏体晶界处和晶内的析出相发生完全溶解；搅拌摩擦焊缝由细小且均匀的板条马氏体组成，晶界处的M₂₃C₆碳化物发生溶解，晶内球状MX相无明显变化. 由于形成大量的板条马氏体，电子束焊缝和搅拌摩擦焊缝硬度均显著高于母材. 不同焊接方法对其焊缝的冲击吸收功有着显著影响，电子束焊缝冲击吸收能量仅为母材的12.2%，而搅拌摩擦焊缝则表现出较好地冲击韧性，其冲击吸收能量为母材的90%.

Properties for the electron beam welds and friction stir welds of 9Cr-1.5W-0.15Ta heat resistant steel

9Cr-1.5W-0.15Ta heat-resistant steel was subjected to electron beam welding and friction stir welding process tests, respectively. The effects of different welding methods on the microstructural characteristics and mechanical properties of the welds were studied. The results showed that the electron beam weld was composed of coarse dendritic lath martensite structure, and the precipitates at the austenite grain boundaries and interior were completely dissolved. However, the grain refinement and homogenous microstructure are observed in the friction stir weld. The M23C6 carbides at the grain boundaries were dissolved, while there was no significant change for these spherical MX phase in the grains interior. Due to the formation of a large number of lath martensite structure, the hardness of electron beam weld and friction stir weld is significantly higher than that of the base metal. Difference of welding process methods has a greater impact on the impact absorption energy of their welds: the impact toughness of the electron beam weld significantly reduces, and the impact absorption energy is only 12.2% of the base metal. The impact toughness of friction stir weld is better, and the impact absorption energy is about 90% of the base metal.