Microstructure Sensitive Fatigue Modeling for AM - Toward a Fatigue Digital Thread

Additive manufacturing (AM) offers an exciting new direction enabling the production of otherwise impossible to achieve components. A great deal of progress has been made in the development of AM materials using integrated computational materials engineering (ICME). However, fatigue remains a major hurdle for qualification of new AM materials. In the present work, ICME approaches for microstructure-sensitive fatigue modeling for AM Ni-based super alloys and high-strength Steels are presented. The ICME-based fatigue modeling framework was employed to consider structure-property linkages, accounting for such structural attributes as the microstructure of the printed material, including phase fractions, grain size, and crystallographic texture, as well as internal defects such as subsurface porosity and inclusions, and external defects such as surface roughness. The focus of this work is high-cycle fatigue. The framework is applied to provide location- and loading scenario-specific fatigue life predictions of components based on the processing of the alloy and its resulting microstructure. The extreme statistical nature of high cycle fatigue makes it challenging to qualify new components for fatigue critical applications, but this modeling framework offers an important step toward a fatigue digital thread, accounting for process, structure, property, and performance and predicting fatigue cycles for component life.