The metallurgy and processing science of metal additive manufacturing

TLDR

Additive manufacturing (AM), or 3D printing, builds parts layer‑by‑layer from powder, wire, or sheets, and numerous techniques—ranging from melting to solid‑state joining—have been developed to achieve this. This review explores metal AM techniques, focusing on processing defects, heat transfer, solidification, solid‑state precipitation, mechanical properties, and post‑processing metallurgy. The review compares various metal AM techniques, analyzing their strengths and limitations. Only a handful of alloys are commercially available, yet recent efforts chart a path toward developing new materials for AM processes.

Abstract

Additive manufacturing (AM), widely known as 3D printing, is a method of manufacturing that forms parts from powder, wire or sheets in a process that proceeds layer by layer. Many techniques (using many different names) have been developed to accomplish this via melting or solid-state joining. In this review, these techniques for producing metal parts are explored, with a focus on the science of metal AM: processing defects, heat transfer, solidification, solid-state precipitation, mechanical properties and post-processing metallurgy. The various metal AM techniques are compared, with analysis of the strengths and limitations of each. Only a few alloys have been developed for commercial production, but recent efforts are presented as a path for the ongoing development of new materials for AM processes.