Magnetomechanical effect of low carbon steel studied by two kinds of magnetic minor hysteresis loops

Two kinds of magnetic minor hysteresis loops were simultaneously measured in a low-carbon steel sample under uniaxial tensile stress by using a magnetic probe. For the minor loops measured by the Hall sensor and direct pickup coil, the coercivity HC and hysteresis loss WH showed a sudden increase at an applied field Ha above 3 kA/m due to the stray flux. As to the other minor loops derived from the calculated Ha and indirect pickup coil, no sudden changes in HC and WH took place, and the curves of HC or WH vs applied stress almost paralleled with each other with Ha above 2 kA/m. HC and WH of these two minor loops obtained at suitable Ha showed similar dependences on the applied stress in both elastic and plastic regions. The clear relationship between magnetic properties and external stress is quite applicable in NDE.