Mechanical properties and microstructure evolution of Ti-6Al-4V prepared by selective laser melting in high layer thickness

Abstract

High layer thickness is a method used to improve the formation efficiency of selective laser melting (SLM). In order to investigate the evolution of Ti-6Al-4V microstructure in the case of high layer thickness and to maintain the mechanical properties of specimens in high layer thickness, Ti-6Al-4V samples were prepared by SLM at 100 μm layer thickness. In this work, the mechanical properties of the specimens were tested by universal mechanical testing machine, Vickers hardness tester and Archimedes drainage method. The optimum ultimate tensile strength, yield strength and elongation were 1213 MPa, 819 MPa and 4.63%, respectively, and the maximum density reached 99.26%. The optimum lateral hardness and top hardness were 406.1 HV10 and 391 HV10, respectively. The microstructure of the samples was characterized by optical microscopy (OM) and scanning electron microscopy (SEM), and the prior columnar β grains were observed as well as their internal contained acicular α′ martensite of different sizes. The results demonstrate that the high layer thickness of 100 μm has no serious adverse effects on the density, hardness and tensile properties of the samples fabricated by SLM, but the range of suitable printing parameters is narrow, while the samples prepared in high layer thickness have a similar structure to those prepared in low layer thickness.