The Effect of Beam Scan Strategies on the Microstructure of EBM Additively Manufactured Inconel 738

Abstract

Electron beam melting (EBM) is a form of additive manufacturing (AM) that offers fast, customizable, near-net production of metallic parts by depositing material "layer by layer." In EBM, an electron beam scans across a bed of metal powder, thereby melting the powder in the shape of a desired part. The melted powder solidifies into a layer, the layer is covered with a new layer of powder, and the process repeats. Consequently, any location within the build could be rapidly heated above solid-solid phase transition temperatures several times as the beam scans the layer(s) above [1]. These beam-dependent, cyclic thermal profiles are known to strongly affect morphology and microstructure, resulting in anisotropic grain sizes, macro-and micro-porosity, and complex phase morphologies [2,3]. This directly impacts the mechanical properties of AM-built parts. While these complex thermal profiles can be controlled with beam scanning strategies, they are not fully understood. Understanding and controlling AM thermal gradients in space and time opens the opportunity to design unique, tailored, desirable microstructures.

High Throughput Characterization to Quantify Microstructural Heterogeneities in Additively Manufactured Haynes 282

“…Previous research on Ni-based superalloys has shown that γ' precipitation is strongly influenced by solidification rates and thermal treatments. And precipitation distribution influences mechanical properties such as hardness and tensile strength [5][6]. A wider adoption of AM processes in industry is often challenged by a lack of significant datasets to generate coherent process-structure-property linkages.…”