Design of High Nitrogen Steels

该补助金探索了一个综合的实验和建模计划，跨越几个长度尺度，以促进我们对一类新的含氮Fe-Mn-C-Al合金的理解，这些合金在结构应用中具有巨大的潜力。主要目的是直接联系变形模型与电子计算，促进多组分铁锰合金的设计，包括氮和铝的影响。Fe-Mn-C-Al-N模型合金具有不同的微观结构特征（多晶织构和单晶），在压缩和拉伸载荷下会发生变形。具有特定取向的单晶将被用来隔离孪生与滑移效应。电子结构计算将建立堆垛层错能和短程有序，这将为微观机械粘塑性自洽模型提供输入，以预测变形响应。利用TEM进行的实验研究将提供有关位错相互作用的高分辨率信息，这些结果将用于在更小的长度尺度上检查模型。该资助代表了建立一个系统方法的高度优先权，该方法将结构和性能集成在一起，用于设计对美国经济至关重要的铁基材料。该计划的成功将最终加速新铁基材料系统的设计、测试和采用，而无需进行漫长的加工和测试试验来优化性能。外联活动将包括为材料科学家和工程师举办的高级钢短期课程，以及针对多组分合金的结构和机械性能的高级本科课程开发。

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.