Stress induction in steel parts using alternating magnetic field

In this research, the induction of high-frequency alternating stresses in steel parts using an alternating magnetic field has been investigated experimentally. This treatment, in addition to the induction of alternating stresses, can increase the temperature of the part and facilitate the release of residual stresses. Residual stresses caused by the welding process in the area around the weld line are a good example of the applications of this method. This method is very fast, and it can be used for small or large parts without space limitations. Also, the necessary equipment can be prepared easily at low costs.In this study, a small coil with an iron core was used to induce the magnetic field, and a simple and cheap electric board was used to create an oscillating current in the coil. The electric board employs a high-frequency electronic switch in a DC circuit to generate a rectangular waveform voltage. The obtained experimental results show that the steel part can resonate at frequencies close to the first longitudinal natural frequency or its subharmonics, and in this case, normal stresses in the order of 100 MPa are induced in the part. By upgrading the electrical equipment prepared in this research, it is possible to increase the induced stresses several times. Hence, employing appropriate equipment, the high-frequency magnetic induction method can be used as an alternative method for stress relief of welded joints.