Description: Despite the rapid commercialization of additive manufacturing technology such as selective laser melting, SLM, there are gaps in models for material microstructure and property prediction that slow qualification and certification. Improvements in coupling microstructure prediction models to local process conditions, validation, and control of material microstructure are required to mature the state of the art. To address these needs, CFDRC in partnership with Arizona State University will develop and apply modeling and simulation tools for prediction and control of microstructure in SLM fabricated parts. The Phase I effort will establish critical software elements, modeling methodology, and experimental data analysis required for Phase II. We will demonstrate the feasibility of high-fidelity models that are capable of predicting the formation of key metallurgical microstructures observed in SLM additive manufacturing processes as a function of the local thermal environment at different locations within the as-built component, reduced models for mapping process conditions to additional microstructure features impacting material quality, and potentially controlling material quality throughout a sample as-built part. The Phase II program will focus on the development of efficient, validated high-fidelity simulation codes and reduced models providing the means to reduce variability in as-built material microstructure and properties, and culminate with the delivery to these tools to NASA researchers and other stakeholders.

Benefits: NASA has identified a number of components within the SLS, including RS-25 engine parts, which provide the opportunity for significant cost and time savings if additive manufacturing can be used for their production. These high-value AM applications are typically for complex structures that require forming, machining, and welding of multiple pieces using traditional manufacturing methods. SLM provides economic advantages by enabling replacement of such multi-piece machined and welded components with single-piece elements. The proposed modeling tools will provide the needed understanding of how material microstructure evolves during SLM fabrication of such components as a single unit, enabling increased confidence in the resulting part quality.

DoD and their prime contractors will also benefit from rapid process development and improved control of material qualities when applying AM to achieve cost-effective low-volume production. A number of DoD agencies - in particular, DARPA, Air Force and Navy - are also evaluating the functional benefits that can be obtained by a combination of advanced design methods (topology optimization) and AM. The modeling tools and fundamental understanding resulting from this effort will be particularly valuable for quickly developing processes to produce AM fabricated components with high confidence in material quality.