镍铝青铜-钢异质焊接接头组织与性能研究

采用手工钨极氩弧焊对镍铝青铜QAl10-5-5/低合金钢Q355 进行了焊接试验，焊丝采用高Mn 镍铝青铜SCu6338。对焊接接头的微观组织、拉伸、弯曲及冲击性能进行了考察与研究。结果表明焊缝与两侧母材均达到冶金结合，焊缝由α-Cu 相和富铁组织（宏观泛铁带和富Fe 枝晶）组成，富铁组织周围存在少量微米级凝固微裂纹，凝固裂纹在被富铁组织包围的残余铜相中形成，表明焊接时应注意控制钢的熔入量和富铁组织分布均匀性。铜/钢异质界面无明显缺陷产生，形成了一层厚度约2μm 的Fe-Al中间化合物层。焊接热循环作用下，镍铝青铜侧热影响区α 相减少，主要为残余β 相和α/κ 共生相为主，其韧性较焊缝和钢侧热影响区低。Q355 侧热影响区为贝氏体组织。焊接接头弯曲测试后表面无宏观缺陷，接头拉伸均断在Q355 母材区域，表明焊接接头焊接力学性能良好。

Welding tests were performed on nickel-aluminum bronze QAl10-5-5 and low-alloy steel Q355 via gas tungsten arc welding (GTAW), using high-Mn nickel-aluminum bronze SCu6338 as the filler wire. The microstructures, tensile, bending and impact properties of the welded joints were systematically investigated. The results show that the weld achieves metallurgical bonding with both base metals on both sides. The weld consists of α-Cu phase and iron-rich phases (macroscopic iron-rich bands and Fe-rich dendrites), with a small number of micron-scale solidification microcracks around the iron-rich phases. The solidification cracks form in the residual copper phases surrounded by iron-rich phases, indicating that attention should be paid to controlling the melting influx of steel and the uniform distribution of iron-rich phases during welding. No obvious defects are generated at the copper/steel heterogeneous interface, and a Fe-Al intermetallic compound layer with a thickness of approximately 2 μm is formed. Under the welding thermal cycle, the α phase in the heat-affected zone (HAZ) of the nickel-aluminum bronze side decreases, and the microstructure is mainly dominated by residual β phase and α/κ eutectic phase, whose toughness is lower than that of the weld and the HAZ on the steel side. The HAZ on the Q355 side exhibits a bainitic microstructure. After the bending test, no macroscopic defects are found on the surface of the welded joint, and all tensile fractures of the joint occur in the Q355 base metal region, indicating that the mechanical properties of the welded joint are excellent.