Quick Facts/or Benefits*

Titanium (Ti) has long had appeal to metal designers; there exists, after all, nearly 40 years of modern industrial practice to support its use.  The following is a brief listing of some significant facts and/or important benefits offered by titanium allows:

• Ti's density is about 60% of that of steel.

• Ti's cost is about 1.3 times that of stainless steel.e very helpful when intricate shapes are involved.)

• Ti's modulus is 55% that of steel.

• Ti is exceptionally corrosion resistant; this feature often exceeds that of stainless steel in most environments, including the human body.

• Ti may be forged by means of standard techniques.

• Ti is castable, although the investment casting method is preferred. 

• Ti may be processed by means of powder metal technology, including metal injection molding.

• Ti is joinable. (This may be achieved by means of fusion welding, brazing, adhesives, diffusion bonding, and fasteners.)

• Ti is formable and readily machinable, assuming reasonable care is taken.

• Ti is available in a wide variety of types and forms, and so no real development is required in most cases.

Ti and Ti Alloy Characteristics

The commercially pure (CP) titanium, along with the alpha and near-alpha titanium alloys, generally demonstrate the best corrosion-resistance qualities.  They are the most weldable of the titanium/titaniuim alloy family.

Pure titanium usually has some amount of oxygen alloyed with it.  The strength of CP is affected by the interstitial (oxygen and nitrogen) element content.

Alpha alloys usually have high amounts of aluminum which contribute to oxidation resistance at high temperatures.  (Alpha-beta alloys also contain, as the principal element, high amounts of aluminum, but the primary reason is to stabilize the alpha phase.)

Alpha alloys cannot be heat treated to develop higher mechanical properties, because they are single-phase alloys.  The addition of certain alloying elements to titanium permits the alloys to be heat treated or processed in the temperature range where the alloy is two-phase (alpha and beta).  The two-phase condition permits the structure to be refined and, by permitting some beta to be retained temporarily at lower temperature, enables optimum control of the microstructure during subsequent transformation when the alloys are "aged" alfter cooling from the forging or solution heat-treatment temperature.

The alpha-beta alloys, when properly treated, have an excellent combination of strength and ductility.  They are stronger than the alpha or the beta alloys.

The beta alloys are mastable; that is, they tend to transform to an equilibrium, or balance of structures.  The beta alloys generate their strength from the intrinsic strength of the beta structure and the precipitation of alpha and other phases from the alloy through heat treatment after processing.

The most significant benefit provided by a beta structure is the increased formability of such alloys relative to the hexagonal crystal structure types (alpha and alpha-beta)

*Reference:  Titanium - A Technical Guide - edited by Matthew J. Donachie, Jr. - ASM Intl