热处理对钛合金激光填药芯焊丝焊接接头组织和性能的影响

Effect of Heat Treatment on Microstructure and Properties of Titanium Alloy Welded Joint by Laser Welding with Flux-Cored Wire

通过激光填丝焊接方法并采用自主开发设计的钛合金药芯焊丝,进行TC4钛合金板的焊接,对获得的焊接接头进行920℃/1 h+650℃/2 h固溶时效处理,并与焊态焊接接头的组织性能进行对比分析。结果表明:热处理态焊接接头焊缝由α_(p)相、α_(s)相集束、α_(gb)相典型的三态组织及点状分布的残留β相构成,未见焊态焊缝中的α’马氏体组织,使焊缝的强度-塑性-韧性得以兼顾;热处理态焊接接头强度降低但延伸率和室温冲击韧性增加;热处理态焊接接头拉伸断口由大量撕裂唇包围,韧窝深且均匀,呈微孔聚合韧性断裂。焊态焊接接头中焊缝区晶粒间的取向差大于15°的大角度晶界占比约83.78%;热处理态焊接接头焊缝中晶粒间的取向差大于15°的大角度晶界占比约为90.21%;通过XRD测试,发现焊态焊缝中主要由α’马氏体组成,还有少量极弱的多角度α相衍射峰,而热处理态焊缝中α相衍射峰中心角度位置与焊态焊缝中α’马氏体一致,另外还发现了较为尖锐的β相(110)衍射峰。

Ti-6Al-4V titanium alloy plate was welded by a laser beam with self-developed titanium alloy flux-cored wire.The welded joint was solution treated at 920°C for 1 h and aging treated at 650°C for 2 h,and its microstructure and properties were compared with those of the as-welded joint.The results show that the heat-treated welded joint is composed of a typical tri-modal microstructure containingα_(p)phase,α_(s)phase colony,andα_(gb)phase,as well as punctate distributed residueβphase.α'martensite microstructure in the as-welded joint is not found in the heat-treated joint,which makes the strength,plasticity,and toughness well balanced and maintained.The strength of the heat-treated welded joint is reduced,while elongation and impact toughness at room temperature are enhanced.The tensile fracture of the heat-treated welded joint is surrounded by massive shear lips.The dimples are deep and uniform,presenting as microvoid coalescence ductile fracture.In the as-welded joint,the proportion of large-angle grain boundaries with misorientation between grains in the weld zone greater than 15°accounts for 83.78%,and in the heat-treated welded joint,the proportion is about 90.21%.Through XRD test,it is discovered that the as-welded weld is mainly composed ofα'martensite,with a small amount of extremely weak multi-angleα_(p)hase diffraction peak.In the heat-treated weld,the central angle position ofα_(p)hase diffraction peak is consistent with that ofα'martensite in the as-welded weld,with a sharpβphase(110)diffraction peak observed as well.