Strength of Torsional Pre-Strained Specimen of Aluminum and Observation of Fatigue Fractured Surface

Abstract

The strength of torsional pre-strained specimen of aluminum was investigated. After torsion, the hardness of the specimen varied from surface layer to center section in cross sectional area. The tensile strength and fatigue limit were improved after application of the pre-strain, and these were related to the surface hardness. The fracture surfaces of fatigued specimens were different depending on the pre-strained level. Also, the application of the pre-strain affected on the crack growth direction and the detailed crack growth modes.