Nondestructive characterization of hardness variations in cold work tool steels usingmagnetic Barkhausen noise

Hardness is one of the most important features inmechanical properties of cold work tool steels which isaltered by change in heat treating conditions. In temperingprocess of the steel, the hardness variations pattern is asfollows: an initial moderate decrease in the hardness up to400 C due to the recovery mechanism, an increase in thehardness at 500 °C related to the secondary hardeningphenomena, and a continuous decrease at highertemperatures due to the carbide spheroidizing. In this paper,the potential of Barkhausen noise method is evaluated fordetecting the hardness variations of AISI D2 steel partsduring tempering treatment. To produce microstructuralchanges, two groups of samples austenitized at 1055 and1080 °C, quenched in oil and finally each group tempered inthe range 200-650 °C. The results show that thenondestructive method could be used to detect secondarycarbides formation during tempering treatment.

کلیدواژه ها:

Hardness variations ، Nondestructive method ، Barkhausen noise ، Heat treatment ، Cold work tool steel