Effect of surface texture on the initiation and propagation of small fatigue cracks in a forged 6082 aluminium alloy

Abstract

The influence of surface texture on initiation and propagation of small fatigue cracks has been studied in a forged AlMgSi alloy. It has been found that the surface character had little effect on the growth rate although there was about 20% reduction in fatigue life for the as-forged surfaces. Examination of crack initiation mechanisms revealed that the impairment in fatigue life was a result of the presence of coarse particles in the as-forged surfaces rather than surface roughness. These coarse particles, which were inadvertently introduced during the forging process, were 20–80 μm in diameter and considerably shorten the crack initiation period.