Spatial microstructural analysis for selective laser melted components

Abstract

Inconel 718 (IN718) is a nickel-based superalloy that exhibits excellent tensile and impact resistant properties along with good corrosion resistance at high temperatures. Due to the work hardening property of IN718, the machinability of this superalloy is low , which paves a path to adopt the selective laser melting (SLM) process to fabricate IN718. SLM process is governed by process parameters like hatch spacing, scan speed, layer thickness, scan pattern and laser power. This variation in these parameters shall influence the microstructural properties. The various scan patterns adopted for this study are chess, stripes, flow-optimized, and customized scan strategy. These various scan patterns shall cause a variation in the area of the heat-affected zones to change the temperature gradient, which thereby determines the grain size ranging from equiaxed to elongated. There is a difference between the magnitude of thermal gradients generated between the lower layers and top-most layers during the build process. As the microstructure of the part is dependent on the thermal intensity between the layers, it is necessary to study the effect of scan strategy on the microstructure. The study focuses on the effect of the variation in scan patterns on the microstructure of the part.