Collaborative Research: Evolution of Strain and Microstructures in the Presence of Solute Hydrogen - a Mulitscale Experimental Investigation

氢脆是金属结构的一种突然的灾难性失效，其损失相当于国内生产总值的3%。这种增强的故障机制对从化石燃料驱动的运输系统过渡到氢气驱动的运输系统提出了重大挑战。要做到这一点，必须发现氢促进失效的机制。这一进展将使氢环境中使用的合金的设计以及预测部件寿命的模型的开发成为可能。威斯康星大学麦迪逊分校和康奈尔大学之间的这项实验性合作努力试图确定驱动氢增强故障的基本机制。在这方面接受教育的学生将通过与日本九州大学的教职员工及其国际碳中性能源研究所的合作获得国际经验。此外，PIS将开发和分发强调金属系统机械性能的基于工程的课堂活动。氢环境对金属结构机械性能的有害影响是有据可查的，但导致增强的突然失效的根本机制仍然难以捉摸。这项合作工作将采用多尺度实验方法，旨在测试溶质氢可以加速微观结构(应变)演变的前提，以及随之而来的高氢浓度，建立决定断裂路径和机制的局部条件。在康奈尔高能同步加速器源(CHESS)上，将利用高能X射线衍射和原位机械加载来动态地探索氢对微尺度晶格应变和取向演化的影响。这项工作将与在不同条件下加载不同程度应变的材料的透射电子显微镜中的加载后微结构表征相结合，包括在现场测试中使用的材料。这一前提的确认将为设计耐氢微结构以及基于物理的预测模型提供基础。

Hydrogen embrittlement, a sudden and catastrophic failure, of metallic structures, accounts for losses equal to 3 percent of the gross domestic product. This enhanced failure mechanism presents a significant challenge to transitioning from a fossil fuel powered transportation system to one powered by hydrogen. For this to occur, the mechanisms by which hydrogen enhances the failure must be discovered. This advance will enable design of alloys for use in hydrogen environments as well as development of models to predict component lifetime. This experimental collaborative effort between UW-Madison and Cornell University seeks to identify the fundamental mechanisms driving the hydrogen-enhanced failure. Students educated in this effort will gain international experience through collaboration with faculty at Kyushu University in Japan and their International Institute for Carbon Neutral Energy Research. In addition, the PIs will develop and distribute engineering based in-class activities that emphasize mechanical properties of metallic systems.The deleterious impact of a hydrogen environment on the mechanical properties of metallic structures is well-documented and yet the fundamental mechanisms driving the enhanced sudden failure remain elusive. This collaborative effort will employ a multi-scale experimental approach designed to test the premise that solute hydrogen can accelerate the evolution of the microstructure (strain) and it, along with attendant high hydrogen concentration, establishes the local conditions that determine the fracture path and mechanism. The influence of hydrogen on the evolution of microscale lattice strains and orientations will be probed dynamically using high energy x-ray diffraction and in-situ mechanical loading at Cornell High-energy Synchrotron Source (CHESS). This effort will be coupled with post-loading microstructure characterization in the TEM of materials loaded to varying degrees of strain under different conditions, including those used in the in-situ testing. Confirmation of the premise will provide a basis for design of hydrogen tolerant microstructures as well as for physically-based predictive models.