13. Residual Stress Response to Peening in Metallic Glass

Normally, the residual stresses as a result of shot peening, include compressive surface stresses on the treated side and tensile stresses on the subsurface. Residual stresses from shot peening of Bulk Metallic Glasses have been beneficial for improving their plasticity in compression. Recently, significant residual stresses were observed in abrasive treated metallic glass ribbons using a process similar to shot peening. Significant thermal residual stresses have also been predicted in amorphous metals, from the rapid quenching needed to retain their structure. Early measurements used neutron diffraction to identify the thermal stresses in metallic glasses. Peening using glass beads leads to curvature as a result of surface stresses. Optical measurements show a reduction in ribbon thickness. XRD measurements on the abrasive treated metallic glass also showed shifts of the broad amorphous diffraction hump compared to untreated ribbons, indicative of the change in residual strain. The resolution of X-ray strain measurements on amorphous metals and the relaxation of thermal residual stresses were considered for validating the prediction.