Explanation

Uneven heating of objects or uneven expansion coefficients of each component. The stress generated during heating or cooling is called thermal stress. Objects expand when heated. When the heating of each part is uneven or the coefficient of expansion is different, the expansion of each part is different, leading to distortion and the generation of thermal stress. There are many reasons for thermal stress. For example: ① There are temperature gradients in components, such as steam boiler tubes, turbine blades, etc.; ② There is a temperature difference between the components, such as the thermal expansion joints in the pipeline: ③ the thermal expansion coefficients of the components are different, such as weld pieces of different materials; ④ The component or sample is quenched (such as quenching) or heated (such as high-frequency surface heating).

Classification