A study on stress, reflection and double shot peening to increase compressive residual stress

The technique of shot peening is commonly used to increase the fatigue limi t of a steel. However, there are many practical difficulties in applying it to very high HV steel and complicated components. To overcome these proble ms, the authors proposed two new methods: stress double shot peening and st ress reflection double shot peening. Both techniques were applied to quench and tempered steel (QT steel) and induction-heated steel (III steel). The main results were as follows: (a) by double shot peening, the compressive r esidual stress near the sample surface was increased considerably; (b) by s tress shot peening, the maximum compressive residual stress (sigma (max)) a nd the surface compressive residual stress (sigma (s)) were greatly increas ed; (c) by stress double shot peening, very high compressive residual stres ses (sigma (max) = -1710 MPa and sigma (s) = -1320 MPa) were successfully i ntroduced into a hard steel (HV is approximately equal to 700); (d) in the new method (stress reflection double shot peening), very high compressive r esidual stresses (sigma (max) is approximately equal to - 1760 MPa and sigm a (s) is approximately equal to - 1460 MPa) were successfully introduced in to a hard steel (HV is approximately equal to 700).