Method for Shot Peening

Abstract

The object of the present invention is to provide a method for shot peening by which a compressive residual stress that is higher than any achieved by the conventional method can be achieved while the thickness of the processed material that is scraped is suppressed. The method is characterized in that the shot materials are shot against the processed material that has the hardness of 750 HV or more that is calculated from equations (1) to (3) below. The shot materials have Vickers hardness that is higher than the hardness of the processed material by 50 HV to 250 HV. The thickness of the processed material that is to be scraped is suppressed to 5 μm or less. HV(m)={f(C)−f(T,t)}(1−γR/100)+400×γR/100  Equation (1) f(C)=−660C2+1373C+278  Equation (2) f(T,t)=0.05T(log t+17)−318  Equation (3) where C denotes the C (carbon) content in the surface layer that is achieved by carburizing (mass %), T denotes the tempering temperature (K), t denotes the tempering time (hr), and γR denotes the amount of residual austenite (vol. %).

Dependencies are inferred from the claim text.