Microstructure and tensile properties of Ti‐62421S alloy plate with different annealing treatments

Abstract

Abstract Ti‐62421S (Ti–6Al–2Sn–4Zr–2Nb–1Mo–0.2Si) is a novel short‐time using high‐temperature titanium alloy. The effects of annealing on microstructure and tensile properties of Ti‐62421S alloy plate were studied through optical microscopy (OM), electron probe microanalysis (EPMA), transmission electron microscopy (TEM), and tensile tests. The results show that, with annealing temperature increasing, the volume fraction of primary α (α p )‐phase decreases while that of transformed β (β t )‐structure and secondary α (α s )‐phase increases. The room‐temperature strength and plasticity are insensitive to annealing temperature. However, with annealing temperature increasing, the tensile strength decreases at 550 °C, while increases at 600 and 650 °C instead. It is suggested that, at 550 °C, the strengthening mechanism is mainly boundary strengthening and the biggest contributor is α p ‐phase by providing α p /β‐boundary area. Above 600 °C, the strengthening mechanism is grain strengthening, where α s ‐phase strengthens the β‐phase.