Heat Treatments and Low Temperature Fracture Toughness of a Ti-6Al-4V Alloy

Abstract

Titanium alloy is one of the reliable structural materials for cryogenic use owing to its high strength, high specific strength and low thermal conductivity. The alloy, however, yields poor fracture toughness compared with other cryogenic structural materials. The toughness of the alloy is highly dependent on the content of iron and interstitials. Heat treatment is also an available method to controll the fracture toughness of the alloy at ambient temperatures). However, there were few attempts to improve the low temperature fracture toughness by heat treatment. The present study was, therefore, conducted to elucidate the effects of heat treatments on the low temperature fracture toughness in a Ti-6Al-4V alloy. The alloy is the typical alpha-beta type titanium alloy and the microstructure can be widely varied by heat treatment.