钛/铝异种合金电弧熔钎焊接接头的组织与断裂行为

摘要

The butt joining of TC4 titanium alloy to 2A12 aluminum alloy was conducted by gas tungsten arc welding using Al-Si eutectic filler wire, and the effects of the welding current on the microstructure and mechanical properties of the weld joint were analyzed. The results show that the maximum tensile strength of 158 MPa is achieved, the top joint fractures in the seam, and the bottom joint fractures at the interface between the titanium alloy and seam at welding current of 110–120 A. The seam consists ofα(Al) and Al-Si eutectic phase precipitated at the grain boundary. The reaction layer consists of the continuous layer TiAl3 phases, the block-like and the long rod-like TiAl3 phase at the top part of the interfacial area of the weld joint. At the bottom part of the interfacial area, the reaction layer includes only the needle-likeτ1 phase. The joint strength abruptly decreases with increasing the interfacial layer thickness up to approximately 300 μm asthe welding current increases to 140 A.%采用Al-Si共晶钎料对TC4钛合金与2A12铝合金异种合金进行钨极氩弧焊接，研究焊接电流对焊接接头显微组织和力学性能的影响。结果表明：当焊接电流为110~120 A时，焊接接头的抗拉强度最高可达158 MPa，此时焊接接头上部断裂在焊缝中，下部断裂在钛合金与焊缝的界面上。焊缝组织主要由α(A1)基体和在晶界析出的A1-Si共晶相组成，而钛合金与液态钎料在接头界面上部化学反应形成3种不同形态的TiAl3金属间化合物，而在接头界面下部只形成针状的τ1金属间化合物。当焊接电流达到并超过140 A时，接头界面化合物厚度显著增至300μm左右，导致抗拉强度急剧下降。