Evaluation of residual stresses in isothermal friction stir welded 304L stainless steel plates

[摘要] Friction stir welding was performed on 304L SS plates in order to heal simulated cracks created by electrical discharge machining. Two different tool temperatures (825 and 725 degrees C) were chosen for this study. Both neutron diffraction and X-ray diffraction techniques were employed to evaluate the residual stresses along two orthogonal reference directions, longitudinal (Sigma yy) and transverse (Sigma xx). The former technique was also used to measure residual stresses at various depths. It was found that, at 1 mm depth from the top surface inside the stir zone (SZ), the longitudinal component was tensile in nature while the transverse component was compressive. The nature and magnitude of the residual stress fields, and the position of the peak residual stresses were found to vary with the weld depth. The SZ of the 725 degrees C weld exhibited higher peak stress than 825 degrees C weld mainly due to a lack of stress relief at the lower temperature.

[发布日期] 2021-10-05

[关键词] Neutron diffraction;X-ray diffraction;304L;SZ;Longitudinal and transverse;FSW