On the High Temperature Mechanical Properties of Ti-8%Al-4%Co Alloy

Abstract

Ti-8%Al-4%Co alloy can be expected to have good mechanical properties at high temperatures because of its high aluminium content. At first, the effect of heat treatment on the creep-rupture properties was investigated. From the results, the heat treatment, i.e., quenching from 700°C, was selected for high temperature use. Then tensile, creep-rupture and fatigue properties at high temperatures were investigated.
The results are as follows:
(1) Up to 500°C in testing temperature, the tensile strength at elevated temperature is slightly affected by testing temperature, and over 500°C it decreases markedly. The tensile strength at 500°C is 82.5 kg/mm².
(2) Above 460°C the crrep-rupture strength is lower than the fatigue strength and below this temperature the latter is lower. The creep-rupture strength for 1000 hr is 32 kg/mm² at 500°C and decreases linearly between 400°C and 600°C. The fatigue strength for 10⁷ cycles is 47.4 kg/mm² at 400°C and hardly varies below 400°C.