Refinement of the grain structure of additive manufactured titanium alloys via epitaxial recrystallization enabled by rapid heat treatment
Zhiyi Zou, Marco Simonelli, Juliano Katrib, Georgios Dimitrakis, Richard Hague
Abstract
The coarse prior-β grain structure in titanium alloys produced by additive manufacturing is associated to mechanical anisotropy and limited fatigue life. Here we report a novel methodology to refine such structure by rapid heat treatment of Ti–6Al–4V produced by laser powder-bed fusion. The refinement was analysed using high-temperature EBSD that showed, for the first time, how high angle boundary β grains nucleated and grew with quasi-equiaxed morphology by epitaxial recrystallization. These findings show the potential for such heating regime to be applied to control grain size, morphology and distribution in a wider category of structural alloys produced by additive manufacturing.