Relationship between microstructure and tensile properties on a near-β titanium alloy after multidirectional forging and heat treatment

Abstract

In this study, a new near-beta titanium alloy, Ti–4Al–1Sn–2Zr–5Mo–8V–2.5Cr, was prepared by induction skull melting (ISM) and multidirectional forging. The effect of aging heat treatment on microstructure and tensile properties of the alloy after solution treatment in the two-phase (α + β) region was investigated. The microstructure results show that the globular primary α phase (αp) and the needle-like secondary α phase (αs) are precipitated in the β matrix. The size of αs increases with the increase in aging temperature, while the content of αs goes up to a peak value and then decreases. The tensile testing results show that the strength increases first and then decreases with the increase in temperature. The variation of ductility presents the opposite way compared with the trend of strength level. When aged at 500 °C, the alloy exhibits an excellent balance of tensile strength (1529 MPa) and elongation (9.22%). And the relative mechanism of strengthening and toughening was analyzed and discussed.