“Materials Science” Challenges in the Additive Manufacturing of Industrial Parts

Abstract

Additive Manufacturing (AM), somewhat like fusion welding, brings into play: (1) complex and interacting physical phenomena such as heat and mass transfer, phase changes (including melting, solidification, allotropic transformations and diffusion phenomena such as epitaxial growth, grain growth), (2) a number of process variables associated to the moving heat source (e.g., its power, power distribution, relative speed, size, all affecting energy density), its paths (e.g., linear, circular, oscillatory), and added metal feed rate via powder, wire, or ribbon, all controlling deposit dimensions, aspect-ratios, and properties, including defects. The effect of successive thermal cycles, as induced by the heat source moving away from an already deposited metal further adds to the overall challenge of fabricating parts with industry-compliant physical, mechanical, and electrochemical properties and proper dimensional controls. This paper discusses fundamental aspects of AM from a metallurgical standpoint.