Magnetic memory effect of tensile component under plastic deformation

Influence of plastic deformation on magnetic memory effect was investigated by testing magnetic signal of demagnetized smooth and notched specimens under different tensile deformation levels. The magnetic field distribution curve of the smooth specimen is close to linear in elastic and uniform plastic flow stages, and exhibits pronounced abnormal wave in stress concentration zone only when necking occurs, while that of the notched specimen shows distortion characteristic after the specimen yields. The possible reasons underlying the wave height increment are discussed based on dislocation theory. The horizontal curves of the magnetic memory signals can be used to determine the damaging development trend in the stress concentration zone, and the power function relationship between peak-peak value and strain is fitted to evaluate the degree of plastic deformation. Although the fracture mechanisms of smooth and notched specimens are different, the abnormal waves with crest and trough both appear in the localized damage zone, which is useful for identifying stress concentration early.