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

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.

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。

氢能是实现碳中和目标的重要途径之一，发展氢能是我国能源战略的重要组成部分。高压氢致损伤问题是引起高压氢系统过早失效的主要原因之一，但目前针对高压氢系统常用材料奥氏体不锈钢（γ-SS）的氢致损伤机制仍缺乏系统深入地研究，进而难以实现服役性能的预测和调控。高压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，氢分布特性是氢致损伤研究的重点和难点之一。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），在探明了测试影响因素的基础上，建立了基于SKPFM-TDS的局部氢分布测试方法，发现了不同氢侵入时机的γ-SS中相界、孪晶界的氢分布和偏聚特性，揭示了不同温度发生塑性应变的γ-SS中氢致裂纹周围的微观组织特性，并分析了氢分布规律和氢致裂纹的关联特性；建立了稳态氢扩散与塑性变形耦合模型，形成了裂尖应力诱导氢扩散和分布数值计算模型，揭示了氢致裂纹尖端的氢浓度场特性，探明了微观组织、应力分布等对裂尖氢分布特性和偏聚位置的影响机制，为氢致损伤机制研究以及设计制造阶段服役性能的预测和调控奠定了重要基础，为全多层储氢容器等的抗氢脆性能调控提供了重要数据和理论支撑；申请并授权发明专利3项，参加3项相关国家标准的制定；在国内外学术期刊上发表SCI论文5篇。