Variant selection induced by electropulsing:Optimization in the microstructure of selective laser melted Ti-6Al-4 V alloy

摘要

Selective laser melting(SLM)is one of the most popular addi-tive manufacturing(AM)technologies.As a near-net shape man-ufacturing method,it offers many advantages from the manufac-turing perspective and has attracted more and more current re-search interests in fabricating the workhorse titanium alloy Ti-6Al-4 V[1].Since the high cooling rate of the molten pool and complicated thermal cycle will result in a fine and metastableαmicrostructure,generally,post-process is required to optimize the microstructure for the widespread application need.Hot iso-static pressing(HIP)and traditional heat treatment are the main post-treatments for the SLM-built Ti-6Al-4 V component[2].How-ever,HIP is a high-cost process and most heat treatments could not achieve a microstructure with high strength-ductility synergy and thermostability,e.g.,sub-transus water quenched microstruc-ture showed superior mechanical properties,but the martensite is far from thermodynamic equilibrium;the sup-transus air cooled microstructure has high thermostability but exhibits low elonga-tion[3,4].