Influence of thermal exposure on the tensile properties and microstructures of Ti60 titanium alloy

The bimodal and lamellar microstructures of Ti60 alloy were obtained by different forging processes. The tensile tests were performed at room temperature for specimens before and after thermal exposure. The results show that the bimodal microstructure exhibits the higher ductility than that of the lamellar microstructure under all conditions. After thermal exposure, both of the strength and ductility decrease for all the specimens with alpha-case. However, when the alpha-case was removed before testing, both of strength and ductility increase compared with the specimens with alpha-case. The loss of ductility is mainly attributed to the precipitation of alpha(2) phase during exposure. The alpha-case formation during thermal exposure also contributes to the changes in tensile properties. The fracture behavior of Ti60 alloy is changed after thermal exposure. The fracture mode is ductile for unexposed specimens with bimodal microstructure. However, the quasi-cleavage fracture is the predominant fracture mode for all exposed specimens. (C) 2011 Elsevier B.V. All rights reserved.