Commercially Pure Grade 1
Titanium Grade 1 is the softest titanium with the highest ductility and the best cold formability. Its maximum oxygen content of 0.18 percent gives it the lowest strength of the pure grades, and its excellent formability gives it outstanding resistance to mild-to-high oxidation environments. Grade 1 is selected for chemical processing equipment, heat exchangers and applications where forming is the dominant requirement and the service loads are moderate. Its weldability matches the other pure grades, and its corrosion resistance is the baseline of the pure titanium family.
Commercially Pure Grade 2
Titanium Grade 2 has moderate strength with excellent cold formability and weldability, and it has the same excellent resistance to high-oxidation environments as Grade 1. It is the workhorse grade of the titanium industry, balancing strength, formability and corrosion resistance at an attractive cost, and it accounts for a large share of the tubing used in chemical processing, desalination, power plant condensers and marine service. For most general-purpose titanium tube applications, Grade 2 is the default selection.
Titanium Alloy Grade 5 (Ti-6Al-4V)
Titanium Grade 5 has very high strength but relatively low ductility, and its main application is in aircraft and spacecraft, with offshore use growing. The alloy is weldable and can be precipitation hardened, and it offers the highest strength-to-weight ratio of the common grades. Grade 5 tubes are used in high-pressure hydraulic systems, aerospace fluid lines and structural applications where the higher cost is justified by the strength saving. Its reduced formability requires special handling in bending and flaring.
Titanium Grades 7, 11 and 16: The Palladium Grades
Grade 7 is the most corrosion-resistant titanium alloy, offering outstanding resistance to general and localized crevice corrosion in oxidizing and reducing acid environments including chlorides, with physical and mechanical properties equivalent to Grade 2. Grade 11 is the same as Grade 1 but with palladium added for better corrosion resistance, providing optimum ductility and cold formability with useful strength and excellent weldability. Grade 16 is a corrosion-resistant material with a smaller palladium addition of 0.04 to 0.08 percent, offering a good balance of moderate strength, reasonable ductility and excellent weldability. These grades are selected where crevice corrosion and reducing acids are the design drivers.
Titanium Alloys Grade 9 and Grade 12
Titanium Grade 9, sometimes called half 6-4, offers 20 to 50 percent higher strength than the pure grades but is more formable and weldable than Ti-6Al-4V, combining strength, weldability and formability with excellent corrosion resistance. Grade 12 is highly weldable, exhibits improved strength at elevated temperatures, and offers superior crevice corrosion resistance with excellent resistance under oxidizing to mildly reducing conditions, especially chlorides, thanks to its 0.3 percent molybdenum and 0.8 percent nickel additions. Grade 9 suits aerospace tubing and heat exchangers, and Grade 12 suits chemical processing and marine service at elevated temperature.
Selection Method
Select the tube grade from the service requirements in order: the corrosive medium and temperature define the corrosion-resistance class, the pressure and loading define the strength class, and the forming and welding requirements define the formability class. Where corrosion is the only driver, a pure grade is usually sufficient; where strength is also needed, Grade 9 or Grade 12 is the next step; and where maximum strength is required, Grade 5 is the choice. Confirm the final grade against the applicable standard, such as ASTM B338 for heat exchanger tubes, and request the material certificate.
Frequently Asked Questions
Which titanium grade is the softest and most formable? Grade 1, with the highest ductility and best cold formability.
What is the most common general-purpose titanium tube grade? Grade 2, balancing strength, formability and corrosion resistance at attractive cost.
Why are palladium grades used? Palladium additions improve resistance to crevice corrosion and reducing acids.
What is Grade 9 titanium? Ti-3Al-2.5V, offering 20 to 50 percent higher strength than pure grades with better formability than Grade 5.
Which grade suits elevated-temperature chloride service? Grade 12, with molybdenum and nickel additions giving improved strength and crevice resistance.
