Effect of Shot Peening on Fatigue Limit Stress Concentration Sensitivity of 3 Kinds of Typical Materials for Aeroengine

Abstract

Fatigue curves of C250 steel, TA29 titanium alloy and FGH96 powder metallurgy (PM) superalloy with stress concentration coefficients Kt=1 and Kt=1.7were investigated, and the effect of shot peening on the fatigue curve under the stress concentration condition was also studied. The results show that the 107 conditional fatigue limits of C250 steel, TA29 titanium alloy and FGH96 PM superalloy decrease from 757 MPa, 366 MPa and 566 MPa to 526 MPa, 240 MPa and 465 MPa respectively while the stress concentration coefficients increase from Kt=1 to Kt=1.7, indicating that the three kinds of high-strength materials have the stress concentration sensitivity of fatigue limit obviously. Moreover, after shot peening, fatigue limits rise to 597 MPa, 297 MPa and 530 MPa respectively when the Kt is 1.7, which indicates that shot peening can mitigate fatigue limit stress concentration sensitivity of high-strength alloys from a technological point of view. On the other hand, the 105-cycle and 107-cycle strength difference of titanium alloy and PM superalloy is reduced with the increase of stress concentration coefficient, showing that shot peening can reduce the dispersion of fatigue test data.

Keywords

• typical materials for aeroengine
• fatigue limit
• stress concentration sensitivity
• shot peening