Abstract
A new combined process for improving the fatigue strength of carburized steels has been developed. This process consists of two treatments : shot peening and chemical polishing. Shot peening yields a high compressive residual stress near the surface of a workpiece, and chemical polishing removes the oxidized and nonmartensitic layer which is harmful to fatigue strength. Since the chemical polishing by the developed solution of 1 mol/l HF and 2 mol/l H2O2 can be conducted by immersing the workpiece in the solution, it is easy to treat complex shaped workpieces. Furthermore, a smooth surface and high compressive residual stress are obtained by treating with chemical polishing after shot peening. The factors of increase of fatigue strength by means of the new combined process for carburized notched specimens are l.76 on the notch radiusρ= 0.5 mm, 1.63 on ρ=1.0 mm and l.51 on ρ=2.0 mm.
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