Most of the higher strength titanium alloys exhibit excellent resistance to general corrosion and pitting corrosion in near-neutral environments which are neither highly oxidizing nor highly reducing.

The metallurgical condition of the alloy plays a relatively minor role in corrosion performance, since oxide film stability is assured in these situations.

When severe crevices exist in hot aqueous chloride media, most high strength titanium alloys will exhibit slightly reduced crevice corrosion resistance compared to unalloyed titanium. The titanium alloys rich in molybdenum, however, exhibit excellent resistance to this form of attack. It is for this reason, along with its favorable strength and low density, the high molybdenum 3AI-8V 6Cr-4Zr-4Mo alloy is a prime candidate for high temperature sour oil well and geothermal brine well production tubulars and other downhole components.

General corrosion resistance of high strength titanium alloys in strongly oxidizing or strongly reducing environments may diminish as aluminum and/or vanadium alloy content increases. Improvements in resistance to hot reducing acids can be achieved by increased alloy molybdenum content. The effects of various alloying elements on titanium alloy corrosion have been studied which indicate that suitable high strength alloys can be selected for a wide range of aggressive environments.

Another major consideration is resistance to stress corrosion cracking. Although the common industrial grades of titanium are generally immune to chloride stress corrosion cracking, certain high strength alloys may exhibit reduced toughness (Klc) values and/or accelerated crack growth rates in halide environments. Most of these alloys will not exhibit any susceptibilities to stress corrosion cracking (SCC) in smooth or notched conditions. However, above 250°C, resistance to hot salt SCC should be considered if chlorinated solvents, chloride salts, or other chlorine-containing compounds contact component surfaces.

High strength titanium alloys can successfully avoid stress corrosion cracking related effects by consideration of alloy chemistry and/or preferred alloy heat treatments and microstructures. Selection of extra low interstitial grades or alloys with transformed beta microstructures may offer significantly improved alloy toughness and resistance to stress corrosion cracking.

In summary, although high strength titanium alloys possess corrosion resistance which is generally superior to that of most common engineering alloys, consideration should be given to selecting a titanium alloy with full compatibility to a given environment. With the wide family of titanium alloys commercially available today, optimum high strength titanium alloy selection is almost always possible for a given environment. Technical consultation is available to assist the designer/user in achieving this end.