Fatigue crack growth behavior in a welded α-β Ti-Al-Mn alloy in relation to micro structural features

Although the fatigue behavior of titanium alloys in various heat-treated conditions has been studied in detail, welded joints in these alloys have not received similar attention. In the current work, fatigue crack growth studies have been conducted in weld fusion zones of a dilute structural α-β Ti-Al-Mn alloy, with particular reference to their microstructural features. Crack growth rates were measured in various welded and post-weld annealed conditions. It has been shown that in all these conditions the weld fusion zones exhibit crack growth rates lower than that in the parent material. Heat treatment after welding decreases crack growth resistance in relation to the as-welded condition. The results are explained in terms of the lamellar microstructures of the weld metals, structural coarsening during annealing and the residual stresses that arise during welding.