A novel approach of accurately evaluating residual stress and microstructure of welded electrical steels

• Residual stress in welded steels was accurately determined by the Barkhausen noise.
• Deviation between MBN and XRD in stress evaluation was within acceptable limits.
• The results were verified by microstructural and mechanical characterization.
• Stress was in-situ monitored and correlated to MBN values by a calibration curve.
• The results imply possible applicability of MBN in NDT of various welded steels.

In the present research work the determination of residual stress distribution in welded non-oriented electrical steel samples is discussed. Tungsten inert gas was used for the welding method. Residual stress was directly determined through deformation measurements and appropriate math calculations. Two methods were used: the magnetic, non-destructive method of Barkhausen noise and the semi-destructive method of X-ray diffraction. In order to evaluate the accuracy and reliability of the magnetic method applied, the steel samples were subjected to both compressive and tensile stresses and the magnetic noise values were correlated to residual stress values through an appropriate calibration curve. The results were then verified by the XRD method and were further evaluated by examining the microstructure and the mechanical properties of the as received and welded samples through scanning electron microscopy and hardness measurements, respectively. It was found that the deviation between the two methods was within acceptable limits, thus implying potential applicability of the MBN method in non-destructive testing of materials.