Low-cycle and dwell fatigue properties for a near alpha titanium alloy Ti–6Al–3Nb–2Zr–1Mo

As a new type of marine titanium alloy, Ti–6Al–3Nb–2Zr–1Mo (Ti6321) has gained attention for its comprehensive properties such as high toughness, strength, weldability, and corrosion resistance. However, there are only a few reports on fatigue properties of Ti6321. In this study, the dwell fatigue and low cycle fatigue tests were performed under various maximum load stresses with the stress ratio of R = 0. Experimental results revealed that the failure can be classified into brittle and ductile types. Fatigue life decreases with the increase of maximum load stress. The dwell time facilitates the accumulation of plastic strain in each loading-unloading cycle and significantly reduces fatigue life. The stress-strain response in the initial period of loading has a decisive effect on fatigue life for both low-cycle and dwell fatigue. The plastic strain energy density in the first loading cycle and fatigue life satisfies the power law relationship, which can be utilized to predict the load holding and low cycle fatigue life of Ti6321.