All titanium grades are not created equal…And with over 40 grades of titanium alloys available, it may be a bit overwhelming to choose the best titanium grade for your unique and challenging application.
But don’t worry, we are here to help…The good news is, there are only few varieties of titanium typically used in the fastener industry and we will do our best to help you understand the differences.
Grade 2 Titanium: This is the workhorse for titanium fasteners and one of the most common grades. This is also known as CP (Commercially Pure) Titanium, which is: 99%+ pure titanium. This grade of titanium is ideal for applications requiring:
- Excellent corrosion resistance to saltwater and brines
- Excellent corrosion resistance to chlorides, including wet chlorine and Cl2
- Excellent corrosion resistance to hot, highly oxidizing acid solutions (For example, FeCl3 and nitric acid)
- Limited corrosion resistance to strong, highly reducing acids (HCl, H2SO4, H3PO4 and HF)
- Moderate strength (50 ksi Yield Strength) at almost ½ the weight of steels and stainless steels
- Light weight and low density metal
Grade 5 Titanium: This is a high strength titanium grade. This alloy of titanium is comprised of approximately 6% Aluminum and 4% Vanadium.
- High strength (128 ksi Yield Strength) material being over 2x the strength of Grade 2 while almost ½ the weight of most steels
- Very similar corrosion resistance as Grade 2 Titanium
- Light weight and low density metal
Less utilized, yet still industrially important are titanium Grades 7 and Grade 23.
Grade 7 Titanium: This grade is known for its excellent corrosion resistance. This alloy of titanium is comprised of approximately 0.15% Palladium. The palladium acts to “supercharge” the chemical resistance of the titanium alloy creating a material with improved corrosion resistance to hot chlorides (and other halides).
Grade 23 Titanium: This is tough stuff. A titanium alloy similar to Grade 5 Titanium, but with lower levels of interstitial elements, such as iron, carbon, and oxygen. This creates and alloy with improved fracture toughness, fatigue crack growth, and mechanical properties at cryogenic temperatures.
So to put it simply, Grade 5 Titanium offers nearly all the corrosion resistance of Grade 2 titanium but with far superior mechanical properties. The trade off, of course, is cost. Grade 5 Titanium is generally a 30-50% premium over Grade 2 Titanium. Typically, when corrosion resistance is needed and strength is not a primary concern, Grade 2 is the most affordable choice. When high strength is required, Titanium Grade 5 is typically selected. Grades 7 will further improve the corrosion resistance of Grade 2 and Grade 23 will further improve the mechanical properties of Grade 5.
Hopefully this technical tidbit you found informative and we would love to hear your comments. Of course if you would like more details please visit our titanium fasteners pages or feel free to contact our materials experts.