Abstract: Since the rule of pulse magnetic treatment, which is a novel method to reduce residual stress in steel structures, has not been clear yet, the magnetic field orientation, which is a key factor influencing the variation of residual stress in the process of magnetic treatment, is studied. Firstly, samples with required stress are manufactured by bead on plate welding. Secondly, residual stress distribution is surveyed by hole-drilling method. Then different samples are processed in the magnetic field with different orientations and the residual stresses are measured again. By comparing the residual stress before and after treat- ment, it is shown that under the same conditions different mag-netic field orientations will lead to different residual stress variations. When the field is parallel to the maximal stress, re-sidual stress is changed imperceptibly, while residual stress can be changed obviously if the applied field is perpendicular to the maximum stress. In order to explain the orientation phe- no-mena, the magnetostriction under different field orientations is investigated. And the experimental results show that magne- tostriction performs dramatic differently with different magnetic field orientations, which may be the main reason to explain the relationship between field orientations and residual stress varia- tions.

Key words: Magnetic field orientation, Magnetic treatment, Magnetostriction, Residual stress