Optimising mechanical properties in alpha+beta titanium alloys

The alpha/beta titanium alloys have played a major role in the development of gas turbine technology but it is doubtful that the growth in mechanical properties that contributed to their current dominance can be maintained into the next century. Future applications will require a more efficient utilisation of their strength and fatigue capability through a clearer understanding of deformation and crack development and by matching their inherent anisotropy with principal load direction. As a contribution to this process, the paper explores the factors involved in the formation of the quasi-cleavage facets that play such an important role in cyclic and time dependent fracture modes and examines influencing parameters such as stress redistribution, microstructure and notch geometry.