Ti–6Al–4V parts obtained by selective laser melting typically have an acicular α′ martensitic microstructure whose ductility is low. Thus, post-heat treatments are useful for increasing ductility. In this work, the effects of sub-β-transus heat treatments on the mechanical properties of Ti–6Al–4V...

Ti–6Al–4V parts obtained by selective laser melting typically have an acicular α′ martensitic microstructure whose ductility is low. Thus, post-heat treatments are useful for increasing ductility. In this work, the effects of sub-β-transus heat treatments on the mechanical properties of Ti–6Al–4V parts with porous structures are correlated with martensite α′ phase decomposition. The precipitation of β phase and the gradual transformation of α′ into α phase by the diffusion of excess vanadium from α′ to β phase are proposed to be the main events of martensite α′ phase decomposition in parts fabricated by selective laser melting. The heat treatment performed at 650 °C for 1 h produced no microstructural changes, but the samples treated for at the same temperature 2 h showed a fine precipitation of β phase along the α′ needle boundaries. The heat treatment performed at 800 °C for 1 or 2 h produced a fine α+β microstructure, in which β phase are present as particles fewer in number and larger in size, when compared with the ones present in the sample heat-treated at 650 °C for 2 h. Heat-treatment of the parts at 800 °C for 2 h proved to be the best condition, which improved the ductility of the samples while only slightly reducing their strength

FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULO - FAPESP

Aberto