添加QCr0.8阻隔层的钛/钢电子束焊接接头组织与性能

采用1.5 mm厚QCr0.8铬青铜作为阻隔层进行了TA15钛合金与304不锈钢的电子束焊接,重点分析了焊接接头的横截面形貌、微观组织和力学性能。结果表明,焊缝中存在约0.5 mm宽的未熔QCr0.8阻隔层,实现了Ti元素与Fe元素的物理隔离,避免了Ti-Fe化合物的形成。铜/钢侧焊缝由铜基固溶体与铁基固溶体组成。而钛/铜侧焊缝中V元素的加入很好地抑制了Ti-Cu界面化合物的大量生成,焊缝组织由铜基固溶体、(Ti,V)基固溶体及少量Ti-Cu化合物组成,提高了该区域的强度和塑性。未熔铜阻隔层在热作用下发生软化,接头拉伸断裂发生在未熔的QCr0.8上,接头抗拉强度为293 MPa,为塑性断裂模式。

Microstructure and Mechanical Properties of Ti/Steel Joint Welded by Electron Beam with Adding a QCr0.8 Barrier Layer

Electron beam welding of TA15 titanium alloy to 304 stainless steel was carried out with a 1.5 mm thick QCr0.8 bronze barrier layer. Cross section, microstructure and mechanical properties of the joint were examined. The results show that a 0.5 mm wide unmelted QCr0.8 barrier layer exists in the weld, and thus Ti element is physically isolated from Fe to avoid the formation of Ti-Fe intermetallics. The Cu/Fe weld is characterized by solid solutions of copper and iron. As to the Ti/Cu weld, the interfacial Ti-Cu intermetallics is restricted by the addition of vanadium element, the weld is composed of solid solution of copper and (Ti, V) with a small amount of Ti-Cu compounds. Consequently, the strength and toughness of this zone are improved. The unmelted barrier layer is softened under the welding thermal cycle. Fracture occurs in the unmelted QCr0.8 alloy, with a tensile strength of 293 MPa and a plastic fracture mode.