Prior-β grain refinement of additive-manufactured Ti–6Al–4 V alloys via trace Si addition

Abstract

Although Ti–6Al–4 V alloys have unique properties, their fabrication and treatment processes should be improved further to enhance their quality. Therefore, a novel method has been developed and applied to study the potential prior-β grain refinement of additive-manufactured Ti–6Al–4 V thin-wall components via trace Si addition. The microstructure and mechanical properties were analysed, and the results revealed that adding trace Si facilitates heterogeneous nucleation, contributing to the columnar-to-equiaxed transition of prior-β grains. The anisotropic percentages significantly decreased from 5.82% to 1.15% after trace Si addition. All the trace Si-added specimens exhibited dimples that are indicative of the ductile failure mode. Additionally, the possible phase-change process for the trace Si addition specimens was explored over several thermal cycles during the solidification process.