Enhanced shot peening effect for steels by using Fe-based glassy alloy shots

The use of Fe-Co-Ni-Mo-B-Si glassy alloy balls as peening shots was found to cause a significantly enhanced shot peening effect for steel sheets, i.e., the increase in the thickness of the shot region, higher hardness and higher compressive residual stress in the shot region, and the generation of much distinct crater-like pattern on the shot surface in comparison with those for conventional cast steel shots and high speed steel shots. It was also found that the endurance life time of the glassy alloy shots is 8 to 10 times longer than those for the conventional crystalline alloy shots. The enhanced effect was interpreted to originate from unique mechanical properties of the Fe-based glassy alloy shots such as lower Young's modulus, larger elastic elongation limit and higher tensile strength which cannot be obtained for the conventional crystalline steel shots. The finding of the effectiveness of the Fe-based glassy alloy as peening shots is promising for future applications.