Abstract: Researching the propagation characteristics of ultrasonic wave in solid with high temperature and non-uniform temperature gradient is exceedingly essential. According to the relationship between temperature gradient and stress gradient, it builds two dimensional finite element model of the ultrasonic wave propagate in mild steel. The disciplinarian between temperature field and positioning accuracy of defects is analyzed. And available experimental data has been used to confirm the correctness of a part of simulation results. The results show that defect positioning error increases due to the following reasons: the rising in temperature; the increasing of temperature difference in?between the two sides of the solid; the increasing of distance defects from the detector. Empirical equation to compensate positioning ultrasonic nondestructive testing is established which can improve the positioning accuracy of defects. Those empirical equations can play a guiding role in engineering.

Key words: high-temperature, non-uniform temperature gradient, positioning accuracy, multi-physics coupling, positioning correction

摘要： 为了研究超声波在均匀温度场以及非均匀温度场作用下的金属材料中的传播规律，提高缺陷检测精度，利用多物理场耦合的方法，建立均匀温度场和非均匀温度场作用下的碳钢中超声检测有限元模型，预测了均匀高温和不均匀温度场下金属材料中缺陷超声检测的探测位置，仿真结果与已有的实验结果基本吻合，然后对仿真的缺陷位置进行数据回归拟合，建立了特定温度场作用下超声缺陷检测位置修正经验公式。研究表明：均匀温度场中金属材料温度的升高、非均匀温度场中固体上下表面温度差的增大以及缺陷与探测器之间距离的增大，都会导致缺陷定位误差的增大。利用回归拟合的缺陷位置修正经验公式，能够显著提高超声缺陷检测的定位精度。

关键词: 不均匀温度场, 定位精度, 多物理场耦合, 位置修正