Ti 6Al-4V is the most widely used titanium alloys and account for more than half of all the titanium sponge used worldwide. Aerospace applications account for 80% of that usage. The remainder is found in defense, marine, medical, chemical, and other industries.
Neither grade of Ti 6Al-4V has corrosion properties quite as good as CP titanium, but both are corrosion resistant in seawater, oxidizing acids, aqueous chlorides, wet chlorine gas, and sodium hypochlorite.
Altering the interstitial levels tends to enhance certain properties; Ti 6Al-4V ELI (Extra Low Interstitials) is a popular alloy where medium strength and good toughness are required. The strength and ductility are similar, but the fracture toughness of the ELI grade is about 25% higher than the standard grade. The ELI grade is usually specified for seawater applications (MIL-T-9047) and for medical use (ASTM F136). A medical grade of Ti 6Al-4V (ASTM F1472) also exists.