针对火电厂锅炉和主蒸汽管道P92钢服役时的热老化状态检测,开发了基于MBN(磁巴克豪森噪声)效应的热老化检测仪器;对不同硬度P92钢进行MBN信号测量,选择了基于启发式硬阈值原则的小波包算法作为滤波算法;得到了MBN信号4种特征值与P92钢硬度值之间的关系;以硬度作为评价热老化状态的参数,对不同服役时长的P92钢试样进行MBN信号检测。试验结果表明,当服役时间小于30 000 h时,材料的硬度有小幅度的增大,当服役时间为30 000～70 000 h时,材料的硬度下降较快,并在服役时间达到70 000 h后,硬度下降趋于平缓,微观上表现为4种强化机制对于材料硬度的影响。

Aiming at the detection of thermal aging state of P92 steel of boilers and main steam pipelines of thermal power plants in service, a thermal aging detection instrument based on MBN effect was developed. The MBN signals of P92 steel with different hardness were measured, and the wavelet packet algorithm based on the heuristic hard threshold principle was selected as the filtering algorithm. The relationships between the four eigenvalues of the MBN signals and the hardness values of P92 steel were obtained. Taking hardness as a parameter for evaluating the thermal aging state, the MBN signals were detected on P92 steel specimens with different service time, and the results showed that when the service time was less than 30 000 hours, there was a small increase in the hardness of the material, and the hardness of the material decreased faster when the service time was between 30 000 and 70 000 hours, and tended to decrease to a After the service time reached 70 000 hours, the decrease of hardness tended to level off, which was microscopically manifested as the influence of four strengthening mechanisms on the hardness of the material.