Low cycle fatigue properties of electron beam welded TC4 titanium alloy

Low cycle fatigue (LCF) properties of electron beam welded (EBW) TC4 alloy were tested and compared with base material (BM) under strain controlled condition. The LCF life of welded joint is obviously lower than that of BM under high Delta epsilon (t)/2 condition, while equal under low Delta epsilon (t)/2 condition, which was explained by the stress-strain loop and plastic feature of microstructure. The failure fracture occurred in BM region, which was attributed to the relatively lower strength and weaker resistance to plastic diformation of BM region compared to the welded joint region. However, near surface crack initiated at the welded joint without further propagating due to high resistance to fatigue crack propagating from coarse beta grain microstructure.