Relationship between magnetic memory signal and stress

To determine the relationship between magnetic memory signal and working stress as well as residual stress, static tensile tests on plate specimens made of Q235 low carbon steel were performed. The variation regularities of normal magnetic field intensities on the surfaces of specimens with and without artificial defects under different working loads and after unloading were investigated respectively, using the magnetometer TSC-1M-4. The test results show that there is a good correlation between the magnetic memory signal and working stress, and whether the specimen is in a certain critical or limit condition can be predicted via the correlation coefficient between two adjacent magnetic signals. The magnetic memory signals before and after plastic deformation after unloading can not be distinguished, but the fractured magnetic memory signal and the corresponding gradient curve have obvious characteristics to be used to identify fracture zones.