Effect of microstructure on tool wear in micro-turning of wrought and selective laser melted Ti6Al4V

Abstract

• Micro turning of wrought and selective laser melted Ti6Al4V is performed. • Tool wear is analyzed considering the microstructure of both the alloys. • SLM Ti6Al4V alloys shows a higher tool wear due to an instability of the β phase. • Equiaxed grains of wrought Ti6Al4V produces a lesser tool wear. Additively manufactured (AM) parts are not often suitable for direct application as they require post-processing to remove the surface imperfections. Moreover, AM parts have a different microstructure than conventionally fabricated parts. In this regard, this article presents a comparative analysis of the effect of microstructure on tool wear during micro-turning of conventionally manufactured and selective laser melting (SLM) or laser powder bed fusion (LPBF) fabricated Ti6Al4V. Primary tool wear mechanisms found are abrasion, adhesion, and built-up edge formation for both the materials. Moreover, edge chipping is found in the case of the LPBF Ti6Al4V attributed to their higher hardness than wrought Ti6Al4V. More tool wear for LPBF Ti6Al4V is primarily caused due to an instability of the β phase at a higher temperature. Alternatively, equiaxed grains of wrought Ti6Al4V show lesser tool wear due to a balanced hardness and yield strength compared to LPBF Ti6Al4V.