Fatigue behaviour of aluminium composites subjected to surface mechanical treatments

This work aimed the evaluation the fatigue behaviour of aluminium matrix composites obtained by powder metallurgy, after a series of surface mechanical treatments. The material was obtained by hot extrusion of powder mixture consisting of aluminium AA 1100 reinforced with 5%, 10% and 15% volume fraction of SiC particles. The fatigue tests were performed in tension-tension mode. All specimens were cycled at a constant stress level. The stress ratio R was 0.1. Machining at different feed rates and shot peening attained the surface finishing. The surface finishing effect on the composite fatigue properties are discussed in terms of number of elapsed cycles versus maximum stress. The results showed great data dispersion. It is demonstrated that coarse machining tends to impair specimens fatigue life when compared to a finer finishing. The increase in the amount of reinforcement is detrimental to the fatigue life. For specimens machined and shot peened, the fatigue life does not show a significant improvement, when compared to other surface finishing.