Influences of T6 Treatment on Microstructure and Creep Properties of Ti-6Al-4V Alloy

摘要

By means of the T6 treatment, the measurement of creep curves and microstructure observation, the influence of T6 heat treatment on the microstructure and creep properties of Ti-6Al-4V alloy is investigated. Results show that trie microstructure of the forged alloy consists of the banded-like a phase and networks β phase. After sub-temperture T6 treated, the microstructure of alloy consist of the block α phase and "networks basket" structure. Under the conditions of the applied stress of 575 MPa at 400℃, the forged alloy displays a lower creep lifetimes, after T6 treated the creep lifetimes of the alloy is enhanced to 548 h from 66 h, which is attributed to the formation of the network basket structure in which the needle-like phase are dispersedly distributed. As creep goes on, the denser dislocations in the a phase are concentrated to occur the dynamic recrystallization for refining grain, which is a main reason of the alloy displaying a better creep lifetimes and plasticity. Thereinto, the creep mechanism of the forged alloy is thought to be the slip of the straight and dislocation are activated on the prismatic planes and pyramidal planes, while the creep mechanism of T6 treated alloy is that wave-like dislocations are activated on the pyramidal planes.