Understanding Hydrogen Embrittlement in Steels from Atomistic Perspective

为了到2050年实现净零排放，并将加拿大定位为清洁可再生燃料的全球领导者，氢气发挥着至关重要的作用。“加拿大氢战略”将氢视为使加拿大成为世界领先的氢技术供应国的机会，并帮助加拿大刺激经济复苏，提供大量高薪就业机会，到2050年实现净零排放。"战略“中确定的主要技术考虑因素之一是氢脆，这与氢储存和运输过程中材料的严重退化有关。 氢脆是一种有据可查的现象，涉及材料机械性能的退化，例如由于扩散氢原子的存在而导致的延展性、强度和韧性的损失。热效应最早出现于世纪末期，几乎所有的工程金属材料都存在热效应引起的构件失效。尽管近百年来，特别是近40年来，人们利用各种先进的实验技术和计算机模拟手段进行了大量的研究，但对HE的潜在机制仍不完全清楚。在过去已经提出了许多机制来解释HE，然而，没有一个可以解释HE在所有不同的条件下，这导致一个结论，在某些情况下，其中一个机制可以成为一个管理机制，而在另一些情况下，多个机制可以协同相互作用。 在目前的研究中，我们建议调查不同的主要HE机制之间的协同作用，即，一个与硬化效应和软化效应相关的其他。特别是，我们将采用分子动力学（MD）和密度泛函理论（DFT）来研究扩散/捕获氢和晶体缺陷之间的相互作用，系统地研究氢输运对静态/动态载荷条件下钢的机械响应的影响。此外，在不同的负载条件下的缺陷的“网络”的存在下，氢运输的情况将被创建，以澄清不同的HE机制之间的协同作用。我们相信，这项研究的成功将提高我们目前在原子水平上对HE的理解，并提供可能的解决方案，以尽量减少氢储存和运输中的HE，这对于将加拿大定位为氢技术的领导者至关重要。

To achieve net-zero emission by 2050 and position Canada as a global leader of clean renewable fuels, hydrogen plays a vital role. `Hydrogen Strategy for Canada' visions the hydrogen as opportunities to make Canada as a world leading supplier of hydrogen technologies, and to help Canada to stimulate economic recovery, provide plenty of high-paying jobs, and reach net-zero emissions by 2050. One of the major technical considerations identified in the `Strategy' is hydrogen embrittlement (HE), which is associated with serious materials deterioration during hydrogen storage and transportation. Hydrogen embrittlement is a well-documented phenomenon involved degradation in mechanical properties of the materials, such as loss in ductility, strength, and toughness due to the presence of diffusive hydrogen atoms. HE was first reported in late nineteenth century, and the component failures because of HE has been observed in almost all engineering metallic materials. Although a large amount of researches with different advanced experimental techniques and computational simulations has been conducted in the last hundred years, especially in the last four decades, the underlying mechanisms for HE is still not completely understood. Many mechanisms have been proposed in the past to explain HE, however, none of them can explain HE in all different conditions, which leads to a conclusion that in some scenario one of the mechanisms could become a governing mechanism, while in some other scenario multiple mechanisms could synergistically interplay. In the current research, we propose to investigate the synergistic interplay between different major HE mechanisms, namely, one associated with hardening effect and the other related to softening effect. In particular, we will employ molecular dynamics (MD) and density function theory (DFT) to investigate the interaction between diffusive/trapped hydrogen and crystal defects to systematically study the effects of hydrogen transport on the mechanical response in steels under static/dynamic loading conditions. In addition, scenarios of hydrogen transport in the presence of a `network' of defects under different loading conditions will be created to clarify the synergistic interplay between different HE mechanisms. We believe the success of this proposed research will improve our current understanding of HE at the atomistic level, and provide possible solution to minimize HE in hydrogen storage and transportation, which is essential to position Canada as a leader in hydrogen technologies.