Effect of Laser Traverse Speed on the Metallurgical Properties of Fe-Cr-Si Clads for Austenitic Stainless Steel Using Directed Energy Deposition

Abstract

This study investigated the microstructural and compositional behavior of Fe-Cr-Si clads produced in stainless steel (STS) 316 L with a decreased laser traverse speed using directed energy deposition (DED). The substrate of all specimens was mostly composed of austenite, while the clad region consisted of the δ-ferrite, martensite, and a small amount of retained austenite. The reduced heat input by increasing the laser traverse speed resulted in decreased dilution of the Ni component and the substrate’s unmixed zone, resulting in a gradual decrease (16−1%) in the face-centered cubic (FCC: austenite) phase of the clad region. In addition, in the clad region composed of body-centered cubic (BCC), the fraction of martensite decreased, but the fraction of the δ-ferrite increased by decreasing the heat input. The reason for this was that dense martensite was formed in the entire clad region owing to a sufficient cooling rate for phase transformation and dilution of the Ni component in the 12 mm/s specimen with the highest heat input. Therefore, to predict the corrosion and wear characteristics of the Fe-Cr-Si multilayer clad manufactured in STS316L, the formation of martensite by the dilution of the Ni component should be sufficiently considered.