抗氢钢薄膜材料的氢氦损伤影响因素及机理研究

This project is applied for the definite item of NSAF (No.41). Hydrogen resistant steel foil (hereinafter referred to as the foil) is a micro-scale material that can be used for hydrogen and tritium environment. However, it is unclear about how to control the microstructure of the foil and its relationship with service performance is not understand. The basic scientific problems related to above issue are the evolution law of the microstructure of the foil and its influencing factors as well as its correlation between hydrogen permeation and damage behavior. In the project, a series of studies for the HR-1 hydrogen resistant steel foil will be carried out. To explore the correlation between the evolution law of the texture, grain boundary structure and the secondary recrystallization, the behavior of grain growth of the foil will be investigated by means of scanning electron microscope (SEM), transmission electron microscope (TEM), X-ray Diffraction (XRD) and electron back-scattered diffraction (EBSD) methods. Analysis of interaction between different types of grain boundaries and hydrogen atom will be conducted by means of positron annihilation technique and first principles study, and the hydrogen permeability of the foil will be measured to establish the quantitative relationship between the microstructure and hydrogen permeation behavior. Helium and hydrogen will be introduced into the foil by ion implantation and gas phase hydrogen charging, and the segregation behavior of hydrogen and helium in different types of grain boundaries will be revealed using EBSD, focused ion beam (FIB), TEM and 3DAP Technology. Thus, a correlation on the thickness, microstructure and property of the foil will be established, which is a theoretic guidance for its safe application in engineering.

抗氢钢薄膜（以下称膜片）是可临氢、氚使用的微米尺度材料。当前瓶颈是对如何进行膜片微观组织调控、以及所形成微结构与服役性能关系缺乏认识，涉及的基本科学问题是微观组织结构演化规律和影响因素，以及其与氢渗透和损伤行为关系。本项目以微米尺度HR-1钢膜片为对象，拟采用SEM、XRD、TEM和EBSD等手段，开展其晶粒长大行为研究，揭示织构和晶界结构演变与二次再结晶行为关系，确定微观组织结构演化规律及影响因素；拟通过正电子湮没和第一原理分析不同类型晶界与氢交互作用，并利用氢渗透实验建立其与氢渗透行为的量化关系；拟通过离子注入和气相充氢技术在膜片中引入氦和氢，综合运用EBSD、FIB、TEM和3DAP技术揭示氢、氦在不同类型晶界偏聚行为，并通过拉伸实验将微结构与膜片损伤行为联系起来。综合各种实验结果，建立膜片厚度-微结构-性能关系，为安全高效的使用微米尺度抗氢钢膜片提供理论指导。

本项目为NSAF联合基金中“培育项目”的明确目标课题，项目的研究目标紧紧围绕微米尺度膜片在工程应用中所遇到的问题。具体目标在于：以冷轧、退火成形的微米级抗氢钢薄膜（以下称膜片）为对象，深入认识膜片退火过程中微观组织的演化规律及其对力学性能的影响，揭示膜片微结构与氢渗透和氢氦损伤行为之间的关系，建立膜片厚度-微结构-性能关系，为安全高效的使用微米尺度抗氢钢膜片提供理论指导，并期望在基本原理上为解决该类膜片所遇到的瓶颈问题提供支持。通过三年多的研究发现，微米尺度抗氢钢膜片的微观组织演化、特别是再结晶和晶粒尺寸长大具有自身的独特规律，不同于一般的块体材料：一方面，由于厚度处于微米尺度，表面和尺寸效应显著影响厚度方向的晶粒长大过程，易于发生二次再结晶；另一方面，微米尺度膜片的微结构特征显著影响氢的渗透和扩散行为，以及膜片的力学性能，特别是当发生二次再结晶后，个别晶粒显著长大，甚至贯穿整个晶粒，显著增加氢的渗透与扩散，降低其强度与塑性。基于尺寸和表面效应研究，确定了膜片材料的再结晶和晶粒长大行为和影响因素，实现了膜片微结构特征控制。基于项目的研究结果，已配合相关单位进行了抗氢钢膜片带材的采购技术条件制订，并进行了三个批次微米尺度抗氢钢带材的供货。项目执行期间，在国内外的期刊上公开发表研究论文6篇、申请国家专利4项。