After tempering of steel parts in the range of 260°C to 400°C there is a risk of Tempered Martensite Embrittlement (TME). The common method for determining embrittlement is the destructive impact test which is expensive and time consuming and control of all products is not possible by this method. In the recent years, the destructive methods are widely replaced by the nondestructive methods considering the capabilities and advantages of these methods in quality inspection of industrial products. In the present research 4340 AISI steel bars have been quenched and tempered in the range of 240°C to 550°C. Then Charpy impact test is applied on all the prepared samples. Finally determining the optimum frequency, nondestructive eddy current testing was applied for all samples and the responses to electromagnetic field such as primary and secondary voltages as well as normalized impedance have been established. The study shows Eddy Current method could be successfully used to distinguish and separate brittle parts due to the microstructure changes.

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