深海等静压对应力腐蚀的影响规律和机理研究

The deep-sea environment stress corrosion and hydrogen induced cracking is an important cause of the threat of deep-sea facilities in service. To satisfy academic curiosity and to bring industrial innovation, it is necessary to understand and predict the mechanism and the behavior of the stress corrosion cracking (SCC) and hydrogen embrittlement (HE) of metallic materials in deep sea. Although great progress has been achieved in this research area, there are still some challenging issues, which hamper the further development of the SCC and HE mechanism for metallic materials in deep sea. Based on our rich research experiences in SCC and HE, the corrosion product film-induced stress, and the coupling behaviors of the SCC and HE, we propose to study the mechanism and behaviors of the SCC and HE of metallic materials in deep sea. The purpose of the proposed research is to reveal the quantitative relationship between the hydrostatic pressure of deep sea with the diffusion coefficient and concentration of hydrogen in materials, with the susceptibility to SCC and HE, as well as the coupling behavior of the SCC and HE of metallic materials in deep sea. Successful completion of the proposed project will facilitate the development of the SCC and HE mechanism, which will have a high impact on both academic research and engineering practice. The anticipated output will become guidelines for the selection of the materials of the deep-sea facilities.

应力腐蚀(SCC)和氢致开裂是威胁深海装备服役安全的重要原因。本项目抓住深海"等静压"这一关键参量和等静压促进氢扩散升高氢浓度的特点，以氢促进SCC及氢脆(HE)与SCC的耦合作用为主线，通过实验和理论分析系统研究深海等静压对腐蚀电化学、腐蚀膜成分、结构和性能以及SCC和HE影响规律，弄清深海等静压影响氢渗透、氢浓度及HE和SCC的机理，探讨深海环境HE和SCC的耦合关系，揭示深海等静压对SCC的影响规律和机理。本项目的研究成果不仅对环境敏感断裂基础理论的发展和深入理解具有重要意义，还可为深海装备的选材和设计提供数据支撑。

本项目开展了深海等静压对金属材料腐蚀、点蚀及应力腐蚀，阴极析氢反应及氢渗透行为的实验研究，以及应力对氢扩散和腐蚀产物膜力学性能对应力腐蚀影响规律的第一原理计算和有限元模拟研究，在Scientific Reports,（2篇），Corrosion Science（1篇），Electrochimica Acta（2篇），International Journal of Hydrogen Energy（2篇）等共发表文章10篇。获得下列研究成果： .1) 搭建了高压氢渗透实验装置，通过深海等静压环境下的恒电流氢渗透实验及数学模型拟合分析，研究了等静压对氢在金属内部扩散的影响, 发表在Corrosion Science 112 (2016) 86-93；2）通过恒过电位氢渗透、交流阻抗测试及第一性原理模拟，证明了等静压能促进水分子解离成吸附氢原子，以及吸附氢原子进入金属次表层，并抑制氢原子复合脱附反应。该结果发表在Electrochimica. Acta 255 (2017) 230–238；3）在上述研究基础上提出了提出等静压与阴极电位耦合作用对金属表面析氢反应的影响。通过不同等静压下恒电位交流阻抗测试及数据模型拟合，对析氢反应动力学参数分析发现，在10至40MPa压力范围内，电位在-1.0至-1.1VSSE范围时，析氢反应由有金属表面氢分压控制，氢吸附模式为Langmuir单层吸附，电位在-1.2至-1.3VSSE范围时，析氢反应由阴极电位控制，氢吸附方式随着等静压增大，由Langmuir单层吸附转为Temkin多层吸附。该研究结果发表在Electrochimica. Acta 247 (2017) 1019-1029；4）通过有限元模拟，建立了阳极溶解型应力腐蚀的内聚力模型。研究成果发表在Scientific Reports 3 (2015) 10579; 5）系统研究了X70钢在等静压环境中的应力腐蚀规律，建立了等静压与pH、载荷之间的关系; 发表在Int J. Hydrogen Energ. 65 (2012) 278–287; 6)研究了等静压对点蚀萌生和扩展的规律, 发表在Materials 10 (2017)1076，Materials 10 (2017)1307.