Corrosion -fatigue behaviour of aluminum alloys

Aluminium has an industrial importance due to its characteristics whichmake it suitable for many applications, especially its low specific weight and highability to form alloys with other elements.In this thesis, we have studied some characteristics of (AI Si 12 Cu Ni alloy[Din 1275]) which is used in the manufacture of some types of pistons in internalcombustion engines which are working (operating) under the simultaneous effectof fatigue and corrosion.The study covered the following aspectsStudy of material behaviour under fatigue stresses in normalenvironmental conditions showed that the fatigue strength is improved bythe precision of casting conditions of the material, and that the fatiguestrength is not affected by understressing.2- The study of crack propagation due to fatigue loading showed that the rateof crack growth is increased by increasing the crack size and that theageing (heat-treatment) process makes the material more tough. Thethreshold stress-intensity factor range for the material, in the agedcondition at zero stress ratio, R, is about 3.0 MPa.m1l2•3- The rate of corrosion attack was measured, and its effect on the statictensile strength showed that it is decreased by small value. However, thehardness, has been reduced greatly, with increasing the time of corrosion.4- By studying the effect of prior-corrosion on the fatigue strength of thematerial, it was found that, the fatigue strength of the material has beendecreased by increasing the time of corrosion.