Functionally Graded Alloys from 316 Stainless Steel to Inconel 718 by Powder-Based Laser Direct Energy Deposition

Extreme serving conditions are demanding on materials with functional microstructure and properties. Additive manufacturing (AM) is an efficient method to fabricate complex geometry functionally graded materials (FGMs) with gradually variable composition and structures as a function of position. In this work, a laser-based directed energy deposition (DED) process was carried out to develop a series of compositionally graded joints from 316 stainless steel to Inconel 718 alloy through computational analysis and experimental characterization. The microstructure, composition, and phases were investigated as a function of position in FGMs. Compared to the traditionally fabricated joint, AM graded materials had more gradient composition and microstructure. The computational-experimental approach is a promising method to design good properties of dissimilar metal joints. The gradient zone that can be flexibly tuned by AM process provides a high throughput design through local tailoring of properties to develop new functional materials.