Fracture mechanism maps for titanium and its alloys

Abstract

Fracture mechanism maps for titanium and a series of its alloys, namely an α alloy (Ti-5 Al-2.5 Sn), a near α alloy (Ti-6 Al-5 Zr-0.5 Mo-0.25 Si) (IMI 685), an α + β alloy (Ti-6 Al-4 V), a β alloy (Ti-15 Mo) and two titanium aluminides (TiAl and Ti₃Al) have been constructed. These maps depict the regimes of stress and temperature in which a particular mechanism of fracture is dominant. The fracture modes include cleavage, ductile fracture, transgranular creep fracture, intergranular creep fracture, dimpled intergranular fracture and rupture. These maps are compared with one another to bring out the role of alloying elements on the fracture behaviour of titanium. A comparison of these maps with those for other h.c.p. and b.c.c. metals has also been made to elucidate characteristics special to titanium alloys.