Effect of cyclic heat treatment on microstructure and mechanical properties of Ti–5Al–5Mo–5V–3Cr–1Zr alloy

Cyclic heat treatment was utilized on Ti–5Al–5Mo–5V–3Cr–1Zr (Ti-55531) alloy to investigate the microstructure and mechanical properties of the material. The effect of cyclic heat treatment on microstructure and mechanical properties of Ti-55531 alloy was investigated using x-ray diffraction, scanning electron microscopy and electron back-scattered diffraction. The tensile test was conducted and the results revealed the decrease in strength and hardness and the increase in ductility of samples after cyclic heat treatment, which are primarily induced by the transformation of primary α and the growth of β grain. The cracks of the samples have primarily occurred along the β grain boundaries where the nucleation of microvoids and their coalescence underwent easier. Furthermore, the increasing times of cyclic heat treatment promoted the transformation of low-angle grain boundaries to high-angle grain boundaries and the formation of new β grains. The results of the present work indicated that the method of cyclic heat treatment could significantly affect Ti-55531 alloy in terms of microstructure evolution and mechanical properties.