Thermal ageing detection of P92 steel based on the magnetic Barkhausen effect

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.