激光冲击增强结构表面抗蒸汽氧化机理及其蠕变-氧化交互作用行为研究

Focus on the long period reliable operation of ultra-supercritical high temperature components, the oxidation mechanism and creep-oxidation behavior of structure surface enhanced by laser shock peening (LSP) will be studied in the vapor environment. The main contents include: (1) Study the effect of LSP on surface micro-deformation and multi-layer oxide structure, and provide a new LSP technology to improve the vapor oxidation properties. (2) Based on self-developed micro-bend creep testing machine with vapor environment，carry out the quantitative analysis of surface chemical reaction under tension and compression loading simultaneously, establish a mechano-chemical model which is coupled oxidation kinetic and creep damage. (3) Through the reasonable description of residual stress release mechanism and multichannel diffusion process of Cr element, establish a creep-oxidation life prediction model based on Larson-Miller parameter. The contents of present study are full of the multidisciplinary field, such as mechanics, surface chemistry and materials. Optimized LSP technology and the basic law of interaction between creep and oxidation after LSP are expected to clarify in present study. Furthermore, realize the effective prediction of creep-oxidation life after LSP. The achievement of present study will enhance the reliability of high temperature components and the core competitive power of major equipment manufacture.

面向超超临界高温部件长周期可靠运行的需求，针对激光冲击增强结构表面抗蒸汽氧化机理及蠕变-氧化交互作用行为展开研究。主要内容包括：（1）考察激光冲击强化工艺对表层微观变形及多层氧化层结构的影响，提供激光冲击改善蒸汽氧化性能的新工艺方法。（2）基于自主开发的微弯曲蒸汽蠕变试验机，同时开展拉-压蠕变载荷下表面化学反应的定量分析与表征，建立激光冲击工艺下氧化动力学与蠕变损伤相耦合的化力学模型。（3）通过载荷、环境相关的残余应力释放机制和Cr元素的多通道扩散过程的合理描述，建立基于Larson-Miller参数的蠕变-氧化寿命预测模型。本研究内容体现了力学、表面化学和材料等多学科领域的交叉，可望获得优化的激光冲击工艺，从化力学角度阐明蒸汽环境下蠕变-氧化交互作用的基本规律，实现激光冲击工艺下材料蠕变-氧化寿命的有效预测，为提升我国高温部件的可靠性、增强我国重大装备制造业的核心竞争力提供科学支持。

面向超超临界高温部件长周期可靠运行的需求，本项目针对表面强化处理增强材料在蒸汽环境下的抗蠕变-氧化性能进行研究，主要研究内容和结果如下：（1）基于自主开发设计的微试样蠕变试验系统，采用微试样三点弯曲蠕变实验法研究P92钢在600℃蒸汽环境中的蠕变-氧化性能并分析了蒸汽氧化层的形成机理。在试验基础上建立了三点弯蠕变氧化模型，与实验结果吻合较好。（2）采用有限元法分析了304不锈钢表面局部腐蚀的力-化学模型，讨论了外加载荷、温度、局部腐蚀尺寸等对其氧化动力学的影响，为实际生产实践提供趋势性预测。（3）采用不同喷丸表面强化工艺增强P92钢表面特性，研究了P92钢在600℃蒸汽环境下的蠕变-氧化性能，在试验研究基础上建立了外载荷、喷丸处理对表面氧化影响的理论修正模型，模型预测与实验结果吻合较好。(4)研究了304不锈钢在多轴交变载荷作用下的化-力学行为，获得了材料在比例和非比例加载条件下的腐蚀疲劳寿命，并分析了多轴腐蚀疲劳开裂机理。