基于应变的高温压痕蠕变全过程变形行为及预测方法

Indentation creep test is a very promising assessment methodology to test materials extracted from in-service components, which has the merits of accurate and nearly nondestructive. Meanwhile, this method can also be used in the local damage analysis. In this project, the deformation behavior of high-temperature indentation creep test under multiaxial and inhomogeneous deformation states is analyzed and predicted. Firstly, the creep curve and microscopic deformation will be analyzed in order to obtain the deformation mechanism and typical feature of indentation creep deformation process. On this basis, a novel indentation creep model will be developed. Meanwhile, the relationship between indentation parameters, creep properties and microscopic deformation mechanism will be revealed. A modified deformation parameter will be proposed to establish a strain-based multiaxial creep model which can describe the three creep deformation phases. Finally, an inverse prediction method based on indentation creep test will be proposed to realize the prediction of deformation behavior and constitutive parameters. The creep behaviors can be predicted based on the indentation creep test accurately and reasonably. This project will broaden the application of indentation creep test and provide the theoretical reference for the safety estimation of in-service materials in actual engineering.

压痕蠕变试验技术具有评价准确，近乎无损，适用于局部损伤分析等优点，是一种极具潜力的在役高温构件安全评价手段。本项目针对多轴、非均匀变形状态下的高温压痕蠕变全过程变形行为及预测方法开展基础研究。首先对高温下材料的压痕蠕变响应曲线和微观变形进行分析，探明高温压痕蠕变变形行为的典型特征和演化机理，构建压痕蠕变力学行为模型，揭示压痕蠕变参数、宏观蠕变性能、微观变形机理之间的关系；引入并定义材料非匹配修正的归一化多轴变形损伤参数，从而建立基于应变的多轴变形演化模型，实现压痕变形与蠕变三阶段之间的完整映射关系；提出基于高温压痕蠕变的逆向评价方法，反向推演蠕变变形及本构参数，实现蠕变全过程变形行为的合理预测。本项目将进一步拓宽压痕蠕变试验的适用范围，为解决在役高温构件的安全运行评定提供可借鉴的理论与应用基础。