Stress relaxation behavior and related mechanism of Ti-6Al-4V alloy with Widmanstatten microstructure

The stress relaxation behavior of Ti-6Al-4V alloy with Widmanstatten microstructure at 200°C, 400°C and 600°C were investigated, and microstructures before and after stress relaxation were observed by TEM. The results show that the stress decreased rapidly at the beginning of stress relaxation, but the stress relaxation rate decreased with the progress of relaxation time, the remained stress tended to stress relaxation limit. The TEM observation combined stress exponent showed the deformation mechanism is dislocation creep at 200°C and 400°C, in which a type dislocation slide occurred; while recovery creep and atom diffusion at 600°C, in which both a and c or a + c dislocation slide and climb occurred.