Melt pool geometry and microstructure of Ti6Al4V with B additions processed by selective laser melting additive manufacturing

This paper documents an investigation into the microstructures and melt pool geometry features of Ti6Al4V + (0, 1, 2, 5, 10, wt%) B alloys processed by selective laser melting (SLM). Single laser-deposited tracks were made on powder-free surface of arc-melted Ti6Al4V-xB buttons. The applicability of powder-free results was supported by evaluation of Ti6Al4V melt pool geometry deposited with and without powder. For each Ti6Al4V-xB composition, melt pools were produced over wide ranges of laser beam power (P) and scan speed (V), with melt pool geometry and microstructure information gathered into mapping in P-V space to develop P-V process window. By varying wt% B and P-V parameter, a variety of microstructures were produced. A promising microstructure consisted of a TiB network with submicron spacing. Melt pool microhardness was characterized, showing evident enhancement from arc-melted baseline for all Ti6Al4V-xB composition. This work identified Ti6Al4V-xB with 2-5 wt% B as a promising composition range for SLM processing and showed the powder-free methodology can provide melt pool scale information for trial alloy composition evaluation. (C) 2019 Published by Elsevier Ltd.