Effects of Aging Treatments on the Mechanical Behavior of Ti-15V-3Cr-3Sn-3Al Alloy

Abstract

The effect of aging treatments on the mechanical properties and microstructures of Ti-15V-3Cr-3Sn-3Al (Ti-15-3) alloy was evaluated using tensile, notched tensile, and J-integral tests. The properties for the one-step aged specimens (371 to 648 °C for 8 h) were compared with those for the two-step aged specimens (one-step aged + 426 °C/24 h). An increase in aging temperature of one-step aging resulted in increased notched tensile strength and fracture toughness of the Ti-15-3 alloy. The second-step aging at 426 °C for 24 h caused various degrees of hardening in the group of double aged specimens. Comparing to the one-step aged specimens, increased notch brittleness and decreased fracture toughness were observed in the two-step aged specimens. For the specimens subjected to aging at 648 °C, the formation of thick α layer at β grain boundaries resulted in lower tensile properties and fracture toughness. The fracture modes of the notch-brittle specimens were strongly affected by the distribution, size, and morphology of the α precipitates.