高温蠕变与断裂评价的若干关键问题

简要介绍了现代高温装置的发展现状, 认为高温装置的安全保障是后工业文明时代无法回避的问题. 为了实现重大高温装备的设计制造和安全运行, 高温下材料的寿命预测与结构失效评价是其中关键. 针对基于Arrhenius方程的寿命外推方法存在的问题, 提出要致力研究高温材料蠕变老化过程的物理化学动力学机理; 针对实际结构引入的复杂应力状态,提出应构建拘束下的高温断裂理论; 针对复杂载荷和环境的影响, 应建立多损伤机制下的材料--结构一体化的统一失效评价方法.

SOME CRITICAL ISSUES IN CREEP AND FRACTURE ASSESSMENT AT HIGH TEMPERATURE

The paper briefs the current trends of the construction of high temperature plants. The need of higher efficiency and lower consumption of resources has led to higher operation parameters of the plants. It is thus believed that the safety of high temperature installations is a critical issue that could hardly be circumvented in the period of post--industrial civilization. In order to achieve a reliable design and manufacture and safe operation of the high temperature plants, some fundamental issues concerning life prediction and failure assessment should be studied. Being aware of some very slow chemical reactions occurred in the high temperature materials after a certain period of service time, it is suggested that the physico--chemical kinetics of the high temperature materials during the slow creep process should be established so that the inaccuracy of life extrapolation techniques based on the conventional Arrhenius equation could be avoided. As the actual material in a component is generally subjected to a complex stress state and the machining of a standard fracture specimen from the component is normally not possible, high temperature fracture theory under constraints should be developed to allow the estimation of fracture properties of the material. Furthermore, a unified failure assessment diagram that includes the local fracture property, the limit loading capacity and the damage law is proposed in order to assess the structural safety under complex loading and environment cases.