Design of High Nitrogen Steels

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The grant explores a combined experimental and modeling program that spans over several length scales to advance our understanding of a new class of Fe-Mn-C-Al alloys with nitrogen that have great potential in structural applications. The main objective is to directly tie the deformation models with electronic calculations facilitating design of multi component iron-manganese alloys incorporating nitrogen and aluminum effects. Several model alloys involving Fe-Mn-C-Al-N with various microstructural features (polycrystalline texture and single crystals) will be deformed under compression and tension loadings. The single crystals with specific orientations will be utilized to isolate twinning versus slip effects. The electronic-structure calculations will establish stacking fault energy and short-range order that will provide input to a micro-mechanical visco-plastic self-consistent model to predict the deformation response. Experimental studies using TEM will provide high-resolution information on the dislocation interactions and these results will be used to check the models at smaller length scales.This grant represents a high priority in building a systems approach integrating structure and properties for design of iron based materials that are critical to the US economy. The success of this program will ultimately accelerate the design, testing and adoption of new Fe-based material systems without the need for lengthy trials of processing and testing to optimize the properties. The outreach activities will include a short course on advanced steels for materials scientists and engineers, as well as an advanced undergraduate course development that will address the structure and mechanical properties of multi-component alloys.