Fatigue Cracking of AA2519-Ti6Al4V Laminate Bonded by Explosion Welding

This paper presents test results of AA2519/TI6AL4V composite laminate structure and mechanical properties. The composite laminate was merged by explosive welding using a transition AA1050 alloy layer. The tested composite after formation was annealed, quenched in water and then aged to strengthen it. The heat treatment process was carried out in order to improve the physical and strength properties of the laminate. Weld endurance properties were determined through fatigue testing performed in constant total deformation amplitude (eac) conditions. The paper also describes the influence of test conditions on hysteresis loop shape, process of cyclic material strengthening and weakening, and fatigue life. Low cycle test results were approximated using a straight line with the following formula: σa = K'(eap)n which enables the K' fatigue strength coefficient, and the n' cyclic strengthening index to be determined. Test results also include fatigue fracture surface analysis. Distinctive fatigue fissure characteristics were investigated through studying fatigue fracture surface microstructure using a scanning electron microscope.