Effect of Tensile Prestrain on Fatigue Strength of Aluminum Alloy in High Cycle Fatigue

Abstract

The effect of tensile prestrain on rotating bending fatigue strength of B51-S aluminum alloy in the solution treated and precipitation hardened condition, has been studied at fatigue life in the range of 5 × 104 to 106 cycles. The fatigue strength decreases when the tensile prestrain is 1.5 percent. At a higher prestrain of 3 to 4 percent, fatigue strength is close to that of virgin material. The cyclic stress-strain curves for virgin and prestrained materials are linear. There is no perceptible strain hardening/strain softening of the material under fatigue loading. The cyclic Young’s modulus is about 4 percent lower than the static modulus irrespective of the material condition. The relative disposition of static bending stress-strain curves in the inelastic region for virgin and prestrained materials shows qualitatively the relative disposition of the corresponding S-N curves.