New Alloys, New Processes Advance Titanium Forging Application

TITANIUM, in common with the other industrial structural metals, can be alloyed to improve property levels to match the design requirements of a variety of chosen applications. Unlike copper and iron and other traditional metals however the alloys of titanium are less the discoveries of chance than products of deliberate development based on alloy theory. Commercially pure titanium, 99% plus Ti, at room temperature has a hexagonal (CPH) crystal lattice alpha phase. This transforms to beta phase centred cubic (BCC) lattice at approx 900°C. Titanium alloys are based on stabilisation of one or other of the two phases or the precipitation of compounds within either lattice. Alloys built around the CPH phase are denoted alpha alloys those around the BCC as beta alloys and those which feature both phases in equilibrium at room temperature are alpha‐beta alloys. Interestingly, relatively few of the formulations first developed have survived the test of time. Alloys which in the laboratory looked extremely promising proved too difficult to melt or process in volume, intractable in forging or machining and fell short of their expectations in final application. The one alloy which has so far withstood all challenges to its supremacy in the widest range of applications within the aerospace industry is the alpha‐beta formulation Ti‐6A1–4V. This alloy frequently described as the “work horse” of the titanium industry is available in all semi finished forms and has carried for some 30 years the burden of introducing titanium as a light strong reliable competitive structural metal in aerospace applications.