Study on Stress, Reflection and Double Shot Peening to Increase Fatigue Limit

摘要

The technique of shot peening is commonly used to increase fatigue limit. However, there are many difficulties in applying it to very high hardness steel and complicated components. To overcome these problems, the authors proposed stress double shot peening and stress reflection double shot peening. Both techniques are applied to quench-tempered steel (QT steel) and induction-heated steel (IH steel). The main results are as follows : (a)By double shot residual stress distribution near the sample surface was markedly improved. (b)By lot peening, maximum compressive residual stress (σ_(max)) and surface compressive stress ( σ_s) were markedly improved. (c)By stress double shot peening (σ_(pre)=1400MPa), ideal residual stresses (σ_(max) =-1972MPa and σ_s=-1774MPa) were successfully introduced in hard steel (HV≒700). (d)The new technique (stress reflection double shot peening) is proposed. By this technique, ideal residual stresses (σ_(max)=-1760MPa and σ_s =-1460MPa) were successfully introduced in hard steel (HV≒700).