Abstract
? 2022 Elsevier B.V.Prior β grain evolution and phase transformation of selective laser melted (SLM) Ti6Al4V alloy after subtransus and supertransus solution heat treatments are investigated. A method based on the special angle grain boundaries (in the range of 15–55° and 70–85°) is proposed for a clear and straightforward description of the prior β mesostructure. Post solution treatments below β transus retain the prior β grains and alter the fully martensitic microstructure into a mixture of α and α’/β phases. A non-traditional “bimodal structure” consisting of αP and αS’ phases is produced by subtransus treatments at a relatively high temperature. While treatments above β transus lead to the growth of prior β grains and transform the martensitic α’ phases into β phases first, and then back into α’ martensites again during quenching, leading to a new martensitic microstructure. The microhardness is determined by the α lath thickness and the amount of α’ martensite, and the latter is more predominant.
NSTL
Elsevier