Hysteresis and Magnetic Barkhausen Noise for SAE 1020 and 1045 Steels With Different Microstructures

Barkhausen noise (BN) was measured in SAE 1020 and 1045 steels with different microstructures. It was found that constituents such as martensite and ferrite plus pearlite can be identified from their BN signatures and magnetic characterization data (coercivity and initial permeability). Comparison of the 1020 and 1045 steels suggests that it may be possible to separate ferrite and pearlite, because the BN burst in pearlite probably occurs for higher fields than in ferrite. The BN analysis, hysteresis, and initial permeability data indicate that in martensite, the magnetization reversal occurs essentially by domain rotation, thus explaining the distinct martensite BN signature.