The effect of laser power on mechanical and physical properties of TI-6Al-4V ELI fabricated by selective laser melting

Abstract

This study aimed to examine the differences in mechanical and physical properties of Ti-6Al-4V extra low interstitial (ELI) fabricated by selective laser melting (SLM) between different laser power. The Ti-6Al-4V ELI alloy samples were printed in dumbbell shape by SLM machine (Trumpf/TruPrint 1000, Germany) with 3 laser powers (75, 100 and 125 W), 8 samples for each group. And the other parameters (spot size 30 µm, scanning speed 600 mm/s, layer thickness 30 µm) were kept constantly. All samples were performed under tensile test with universal testing machine. Moreover, The microhardness test was performed. All data were statistically analyzed with one way ANOVA and Tukey’s post-hoc tests (α=0.05). The microstructure was analyzed by optical microscope and mode of failure was observed by SEM. It was found that the group laser power 100 W was the highest mean tensile strength (1189 .67 MPa) and highest mean microhardness (394.94 VHN). The tensile strength in group laser power 75 and 125 W were 424.62 and 329.88 MPa, respectively. And microhardness value in group laser power 75 and 125 W were 368.3 and 369.62 VHN, respectively. Mode of failure after tensile testing in group of laser power 75 and 100 W showed in both ductile and brittle fracture. And the group of laser power 125 W was predominantly brittle fracture. In conclusion the difference in laser power effected the mechanical and physical properties. The laser power 100 W showed the highest mean tensile strength and microhardness significantly compared to the other 2 groups (α=0.05). And this group was found the α’ martensitic phase microstructure.