Some studies on fatigue crack growth rate of aluminum alloy 6061

Aluminum alloy 6061 (AA 6061) finds various usage as structural material. Nowaday, metal matrix composites based on AA 6061 are being used in several applications. The alloy shows a great promise for more applications. According to empirical observations, majority of failures in practice can be attributed to fatigue. Scientist and researches have found that a torn fracture in the AA 6061 and MMCs matrix material takes place due to fatigue only. Hence, it is necessary to study this in the case of the AA 6061 in detail. The fracture takes place through a crack and most of the cracks are developed due to fatigue loading only in the AA 6061 material components. Once we understand the fatigue behavior of the material AA 6061, it is very easy to predict the life of the component through fatigue crack growth rate graph. Past literature reveals that hardly anyone has carried out fatigue testing and fractographic study for AA 6061. In this report, tensile properties of AA 6061 are determined as basic information for conducting fatigue test. By using BiSS 50 kN, servo-hydraulic testing machine, fatigue testing on compact tension (CT) specimens was done, which was not tried earlier. Fatigue tests were performed according to ASTM standards. DAQ 2350 hardware options for graphic interface and auto calibration are used to obtain the fatigue crack growth rate graph. Through fractographic analysis, during fatigue fracture of AA 6061 ductile striation with dimpled rupture and ridges, cracks, grooves are observed due to voids present in material. Hence AA 6061 is considered as potential candidate material for automobile and aerospace sectors where high strength with reduced weight and high crack arrest capabilities will contribute to crash worthy design of automobiles/aircraft structures and proved most suitable matrix for MMCs. (C) 2007 Elsevier B.V. All rights reserved