Effects of Processing on Microstructure and Properties of Additively Manufactured Inconel 738

This thesis reports the research findings regarding the microstructure and cracking in a Ni-based superalloys Inconel 738 manufactured by a 3D printing technique called selective laser melting (SLM). A baseline microstructural study identified several unique microstructural features in as-fabricated and heat-treated samples that are not known from conventional casting method. The processing influences on cracking are identified as geometric effect, compositional effect, laser scanning parameters and laser scanning strategies. The cracking problem in SLM process is mainly related to various solidification phenomena explainable by many classic theories, as well as by utilizing newly developed thermodynamic and SLM process models.