Abstract:The influence of heat treatment on the microstructure and damage tolerance property of Ti-6Al-2Zr-1Mo-1V titanium alloy was investigated. The large-thickness Ti-6Al-2Zr-1Mo-1V titanium alloy plate was produced by β-processing, following with duplex anneal in (α+β) phase field and β anneal, respectively. The fatigue crack propagation rate(da/dN) test and the fracture toughness(K_ⅠC) test of Ti-6Al-2Zr-1Mo-1V were performed. The results show that the annealing in (α+b) phase field, with increasing anneal temperature, prior β grain size and α colony size of Ti-6Al-2Zr-1Mo-1V remained constant approximately, α lamella mean size increases gradually; K_ⅠC increases and da/dN decreases respectively; when annealing in b phase field, prior β grain size and α colony size increases sharply, da/dN decreases drastically. β anneal is better than anneal in (α+β) phase field as to improve the damage tolerance property of Ti-6Al-2Zr-1Mo-1V.

Key words: Ti-6Al-2Zr-1Mo-1V ; microstructure ; crack propagation rate; fracture toughness