奥氏体不锈钢氢致裂纹尖端局部氢分布特性及其演化机制

氢能是我国能源体系的重要组成部分。高压储氢目前应用广泛，但高压氢系统面临氢致损伤的严峻挑战。氢致损伤最直接的宏观表现为氢致裂纹，且其损伤程度与材料中氢浓度密切相关。然而由于试验难度大，导致高压氢系统常用材料奥氏体不锈钢（γ-SS）氢致裂纹尖端的氢分布特性尚不清楚，进而难以实现γ-SS服役性能的预测和调控。本研究创新地结合扫描开尔文力显微镜（SKPFM）和升温热脱附质谱仪（TDS），实现两者的有机协同、相互佐证和补充；在建立并完善基于SKPFM-TDS的氢分布定量测试方法的基础上，针对γ-SS裂尖通常存在大量马氏体的特点，首先探明马氏体对氢分布及偏聚特性的影响规律，获得氢偏聚参量值；而后建立裂尖氢扩散与分布数值计算模型；最后结合SKPFM-TDS和数值模型揭示γ-SS裂尖氢分布特性及其随微观组织、应力分布、温度和时间的演化机制，为探明γ-SS氢损伤机制、建立氢损伤预测模型及性能调控提供支撑。

Development of hydrogen energy is one of the energy strategies in our country. High-pressure hydrogen storage has become the most popular method, while hydrogen embrittlement is one of the challenges for high-pressure hydrogen system. Hydrogen-induced crack is the product of hydrogen embrittlement which has close relation with the localized hydrogen concentration. However, because the measurement of localized hydrogen concentration in metal is a challenging task, the localized hydrogen distribution around hydrogen-induced crack in austenitic stainless steel (γ-SS) is still unclear, which makes it difficult to predict and control the performance of γ-SS. In this project, an innovative method, which combines the scanning Kelvin probe force microscopy (SKPFM) and thermal desorption spectroscopy (TDS), is proposed to study the localized hydrogen distribution around hydrogen-induced crack in γ-SS. First, the hydrogen distribution testing method based on SKPFM-TDS is developed. Second, the influence of martensitic transformation on localized hydrogen distribution and trapping characters in γ-SS is studied using the SKPFM-TDS method. And the hydrogen trap binding energies are calculated. Then, a numerical calculation model to predict the hydrogen diffusion and distribution around crack in γ-SS is developed. Finally, the localized hydrogen distribution around hydrogen-induced crack in γ-SS is investigated using the SKPFM-TDS and numerical calculation model, as well as the evolution of hydrogen distribution with microstructure, stress, temperature, and time. The research results from this project can be useful to understand the hydrogen embrittlement mechanism, predict and control the performance of γ-SS in high-pressure hydrogen environment.