CAREER: Understanding the Corrosion Fatigue Behavior of Additively Processed Metals through an Integrated Experimental and Computational Approach

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This Faculty Early Career Development (CAREER) award will focus on determining the mechanisms governing the corrosion fatigue behavior of additively manufactured metals, especially due to the influence of unique microstructural features and residual stress introduced during processing. Additive manufacturing has gained wide attention in recent years because it can be used to produce geometrically and compositionally complex parts, as well as provide on-demand production and repair capability. Its potential to manufacture true load-bearing parts, however, is not yet fully realized due to several issues. In particular, the complexity of the resultant microstructural features makes it difficult to distinguish their respective effects on fracture and fatigue performance. This project will answer two relevant question with focus on corrosive environments: 1) How does the fatigue behavior of additively processed alloys differ from that of their conventional counterparts under normal and corrosive environments, respectively? and 2) How does the microstructure contribute to the observed differences in behavior? Insights gained from the award will guide the design and manufacture of additively manufactured parts and prolong their service life by limiting the causes of fatigue failure in corrosive environments. Thus, the research will not only promote the progress of science but will also advance national prosperity and welfare by reducing the tremendous financial losses related to corrosion damage. In addition, this award will encourage women in engineering by launching a “Women in Flight” club and perform outreach to high school science teachers and students through creative audiovisual learning modules.The unique microstructure formed in additively manufactured metals merit critical investigation into its effect on environmentally-assisted fatigue behavior. This project will employ a combined computational and experimental approach to: 1) evaluate the macroscopic fatigue properties of conventional and additively manufactured alloys in air and corrosive environment using high-cycle fatigue testing; 2) elucidate effects of microscopic features and defects on the local passivity and corrosion properties using electrochemical microcell and adaptive Kinetic Monte Carlo modeling techniques, and 3) reveal the mechanism and the influence of individual microstructure features and their interaction by developing a microstructure-sensitive multiphysics computational framework based on phase field and crystal plasticity modeling. The features that will be considered are sub-grain dislocation networks, solidification texture, porosity, and chemical heterogeneity, as well as residual stress. It is expected that he experimentally-validated modeling framework will introduce a new capability to advance the mechanistic understanding of deformation and failure of additively manufactured alloys in corrosive environment.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.