Patent ID: 8151613

Claim:
A method for shot peening comprising shooting shot material against a processed material, wherein a hardness HV(m) of the processed material is calculated from equations (1), (2), and (3) and is 750 HV or more, wherein a Vickers hardness of the shot material is higher than the hardness of the processed material by 50 HV to 250 HV, and wherein a thickness of the processed material that is peened is 5 μm or less, HV( m )={ f (C)− f ( T,t )}(1−γ R /100)+400×γ R /100 Equation (1) f (C)=−660C 2 +1373C+278 Equation (2) f ( T,t )=0.05 T (log t+ 17)−318 Equation (3) where C denotes a C (carbon) content in a surface layer that is achieved by carburizing (mass %), T denotes a tempering temperature (K), t denotes a tempering time (hr), and γ R denotes an amount of residual austenite (vol. %).