Peening with glass beads can be detrimental to the surface, causing damage and early fatigue failure. Generally the intensity range when using glass bead is limited to only the "N" scale.
What was the intensity of your peening treatment?
Glass beads will break very easily at higher than 5A intensity so you never should peen while at the "A" range of intensity.
Are you familiar with intensity measurements and the Almen strip, holder and gage?
