Effect of Process Parameters on the Mechanical Properties of Hastelloy X Alloy Fabricated by Selective Laser Melting

Mechanical properties of Hastelloy X alloys fabricated by selective laser melting were investigated and compared with the wrought counterpart. Nano-inclusions (Mo-rich carbides) distributed at the sub-grain boundaries in the selective laser-melted (SLMed) Hastelloy X alloy, whereas micron-scale precipitations existed in the wrought counterpart. The molten pool boundaries widely existed in the SLMed substrate, which acted as an initial site for crack and led to poor plasticity. However, the ultimate tensile strength values of the SLMed Hastelloy X alloys were around 910 MPa and much higher than the wrought counterpart (similar to 750 MPa), which was mainly ascribed to the high-density dislocations enriched at the sub-grain boundaries. Process parameter effects on the mechanical properties were also delineated in this work, and the volumetric energy density for the best mechanical properties of the SLMed Hastelloy X alloy was in the range from 140 to 170 J/mm(3).