对TA1/Cu/X65三层复合板(复层TA1厚2 mm,中间层Cu厚1 mm,基层X65管线钢厚12 mm)进行了钨极氩弧焊(TIG)对接焊,设计并制备了过渡层焊接材料Cu-Ag-Mo-Nb药芯焊丝,从而对焊接接头性能进行有效冶金调控。通过SEM、EDS、XRD、TEM对接头组织特征、界面元素分布进行了分析鉴定,通过拉伸和显微硬度实验测试了接头的力学性能。结果表明,焊缝各层填充金属之间冶金结合良好,且有明显的熔合线和过渡带,其中,在Ti焊缝和过渡层焊缝之间存在宽度大约为150 μm的Ti-Cu冶金反应区,过渡层焊缝和钢焊缝之间的组织主要是铁基固溶体和铜基固溶体。中间Cu夹层和Cu-Ag-Mo-Nb药芯焊丝的使用,抑制了Ti-Fe硬脆金属间化合物的产生,形成了塑性相对较好的铜基固溶体和Ti-Cu、Ti-Ag等金属间化合物。接头的平均抗拉强度为507 MPa,主要由X65层贡献。焊缝硬度在各过渡界面处均发生突变,其中在Cu-Ag-Mo-Nb、ERTi-1焊缝处硬度可高达447和507 HV₁₀₀,对接头塑韧性有很大影响。

Titanium and its alloys with fine corrosion resistance and specific tenacity are widely used in the fields of astronautics, chemical industry and so on. While the pipeline steels with low price and good mechanical properties are always used in petroleum industry. For now, composite panels are widely used in petrochemical industry, aerospace engineering and other fields, which can combine the respective features of the dissimilar materials together so as to meet the special requirements and save a lot of rare and precious metals. Previous studies have showed that the joining of titanium and steel suffered from two major challenges: one was the emergence of continuous distributed intermetallics of TiFe and TiFe₂ in the weld, which could cause brittle fracture with low strength; the other was the occurrence of residual stresses that were caused by the great differences in thermal properties between titanium and steel. This work is aimed to join the explosion-bonded TA1/Cu/X65 trimetallic sheets (titanium flyer plate with thickness 2 mm, copper intermediate plate 1 mm, and X65 base plate 12 mm) with Cu-based flux-cored wires by the tungsten inert gas (TIG) welding. The microstructure and mechanical properties of welded joint was characterized by using SEM, EDS, TEM, XRD and tensile and microhardness tests. The results indicated that the filler metals for each weld layer have obvious zoning by using solid solution phases and intermetallic compounds. There was about 150 μm width Ti-Cu reaction zone between the Ti weld and transition layer weld. The microstructures of Cu-Ag-Mo-Nb/ER50-6 transition interface were composed of Fe-based and Cu-based solid solution. The intermediate copper played an important role in reducing the high temperature residence time of welded joints so as to reduce the interdiffusion of Ti, Fe element. Consequently, the hard-brittle Ti-Fe intermetallic compounds were partly replaced by Cu-based solid solution and Ti-Cu, Ti-Ag intermetallic compounds with relatively good ductility and toughness. The average tensile strength of the butt joints is 507 MPa at room temperature, mainly of that of X65 was obtained. ERTi-1 weld metal exhibited higher hardness than Cu-Ag-Mo-Nb weld metal, and their microhardness values were 507 and 447 HV₁₀₀, respectively. In addition, the microhardness in reaction zone presented a slightly drop. The lowest values occurred in ER50-6 weld metal.