Effect of tensile stress on the variation of magnetic field of low-alloy steel

The surface magnetic field intensity Hp(y) of low-carbon steel plate specimen was measured after tensile test and unloading; variation of Hp(y) was studied. It was found that Hp(y) signals first decreased with increase in stress, and then reversed to the initial field when the stress was greater than 160 MPa. Under yield stress, Hp(y) reached its maximum, and then decreased slightly with further increase in stress. The initial magnetic signals have great impact on the variation of magnetic field.

► Variation of magnetic field intensity with increase in stress was somewhat different from other reports.
► It was found that magnetic field intensity was first decreased with increase in stress and then reversed to the initial ones.
► Under the yield stress, Hp(y) reached its maximum and decreased slightly with further increase in stress.
► Schematic diagram was proposed to explain this phenomenon.