Nondestructive electromagnetic testing of hardened layers on surfaces of steel components

In order to improve the measurement accuracy of hardened layer thickness, we suggest to use combination harmonics in a signal from an attached electromagnetic transducer. The paper describes an instrument for testing a hardened layer and generating a multidimensional digitized signal characterizing this layer. Results of tests of an experimental version of the device by measuring the thickness and hardness of case-hardened layers are given.