Eddy current testing method for hardness of C60 mold steel at different tempering temperatures

The influence of different tempering temperatures on the microstructure, electromagnetic properties and hardness of C60 mold steel was studied. The results show that as the tempering temperature increased, the crystal structure of C60 mold steel underwent phase transformation, the direction of internal magnetic moment changed, led to changes in the electromagnetic characteristic parameters of the material, the ferrite content in the structure was increased, and the hardness of the material was decreased. By comparing the relationship between the hardness and impedance of C60 mold steel at different tempering temperatures, an electromagnetic mathematical model for testing the hardness of C60 mold steel was established. The relative error between the electromagnetic detection results and the actual test results was less than 1%, indicated that eddy current electromagnetic signals could accurately test the hardness of C60 mold steel.