Role of extruded texture on fatigue crack growth in a high strength aluminum alloy thick-walled cylinder

In present study, as a basic step for modeling the fatigue behavior of an extruded Al alloy cylinder, the fatigue crack growth data of the alloy was collected in two orientations. Microstructural analysis revealed that the material had recrystallized grains and clusters of constituent particles aligned in the direction of extrusion. Fatigue life of the samples revealed a shorter fatigue life representing a higher fatigue crack growth rate in transverse direction. The Paris constants C and m were found to be 4 × 10⁻¹¹ and 3.4 for the transverse orientation. The same constants were found to be 2 × 10⁻¹⁰ and 2.6 for the longitudinal direction. Post fracture analysis revealed that the topographical appearance of the fractured surfaces in two orientations was different. The mechanism of crack growth was the formation of striations. The present study revealed that the texture of the constituent particles created during extrusion process has a pronounced effect on the crack growth rate in two orientations. This paper was recommended for publication in revised form by Associate Editor Chongdu Cho Dr. M. A. Malik is a Professor in Department of Mechanical Engineering, College of Electrical and Mechanical Engineering, National University of Sciences and Technology, Rawalpindi, Pakistan. He graduated from Georgia Tech, USA with MS and PhD degrees in nuclear engineering. He has considerable working experience in nuclear research industry. He specializes in impurity transport and modeling and simulation techniques. His current research interests include structural analysis, reliability of materials and modeling and simulation of dynamic engineering systems. He has over 85 publications to his credit.