Ti 6Al-4V STA (Solution Treated and Aged) is a modified version of Ti 6Al-4V. It may be heat treated for high strength in sections under 4" thick. Ti-6Al-4V has excellent hardenability in sections up to 1" thick with strengths as high as 165 ksi.

For maximum strength: solution-treated and aged (STA) condition is: For sheet, 1675-1725°F 5 to 25 minutes, water quench. Age 975°F 4 to 6 hours, air cool. For bars and forgings, 1650-1775°F 1 hour, water quench. Age 900-1150°F 4 to 8 hours, air cool.

Ti 6Al-4V is resistant to general corrosion but may be quickly attacked by environments that cause breakdown of the protective oxide. These include hydrofluoric (HF), hydrochloric (HCl), sulfuric and phosphoric acids. Inhibitors may help for the last three but not for HF. Ti 6Al-4V resists attack by pure hydrocarbons, and most chlorinated and fluorinated hydrocarbons (provided water has not caused formation of small amounts of HCl and HF).

Ti 6Al-4V is susceptible to chloride stress corrosion cracking (SCC), although being among the better of the titanium alloys in this regard. For marine environments silver plated bolts are not used, as silver bonds easily with chlorine in this environment. Ti 6Al-4V is also susceptible to SCC in environments such as methyl alcohol, red fuming HNO3, and N2O4. In the case of red fuming nitric acid, the problem is limited to environments containing less than 1.5% water, or more than 6% NO2. Failure in N2O4 has occurred when oxygen and chlorides were present as impurities.