Introduction to Selection of Titanium Alloys

TITANIUM is a low-density element (approximately 60% of the density of steel and superalloys) that can be strengthened greatly by alloying and deformation processing. (Characteristic properties of elemental titanium are given in Table 2.1.) Titanium is nonmagnetic and has good heat-transfer properties. Its coefficient of thermal expansion is somewhat lower than that of steel and less than half that of aluminum. Titanium and its alloys have melting points higher than those of steels, but maximum useful temperatures for structural applications generally range from as low as 427 °C (800 °F) to the region of approximately 538 °C to 595 °C (1000 °F to 1100 °F), dependent on composition. Titanium aluminide alloys show promise for applications at temperatures up to 760 °C (1400 °F). Titanium and titanium alloys are produced in a wide variety of product forms, with some examples shown in Fig. 2.1. Titanium can be wrought, cast, or made by P/M techniques. It may be joined by means of fusion welding, brazing, adhesives, diffusion bonding, or fasteners. Titanium and its alloys are formable and readily machinable, assuming reasonable care is taken. Some specific examples of product forms are: