Abstract:The stress relaxation behavior of Ti-6Al-4V alloy was studied and the change in microstructure resulted from stress relaxation was observed by TEM. Results show that stress relaxes very fast in the first stage while slowly in the second stage; the relationship between plastic strain rate and stress can be obtained from stress relaxation experiments. The plastic strain rate exponent is 4 at 400℃, and 1.6 at 600℃. TEM observation and plastic strain rate exponent show that the dominant deformation mechanisms are dislocation creep at 400℃, recovery creep at 600℃ and recrystallization at 800℃, respectively. The stress relaxation mechanism figure is given.

Key words: stress relaxation; Ti-6Al-4V alloy; microstructure; deformation mechanism