Magnetic and eddy-current testing of hardened constructional steel subjected to combined strain-thermal treatment

The potentialities of magnetic and eddy-current methods for testing a structural state, wear resistance, and mechanical properties of steel 50 (0.51 wt. % C) subjected to quenching from 850°C, nanostructurizing frictional treatment with a hard alloy indenter, and tempering at the temperatures of 100–600°C are studied. It is shown that the structural state of constructional steel 50 that is subjected to combined strain-thermal treatment can be tested using the eddy-current method upon low temperature (to 250°C) tempering and in the tempering temperature range of 250–450°C, the coercitimetric method and based on the maximum permeability in the temperature range of 100–350°C, based on the residual magnetic induction for major and minor magnetic hysteresis loops in the temperature ranges of 100–400°C and 250–600°C, respectively, and based on the specific resistivity in the temperature range of 100–300°C. Correlations between electromagnetic parameters and hardness, mechanical properties, wear intensity under the conditions of dry frictional that point to the possibility of using eddy-current and magnetic testing of the quality of optimized strain-thermal treatment, which provides a good complex of wear resistance and mechanical characteristics of constructional steel, were established.