1. Chemical Composition & Purity
The primary distinction lies in the maximum allowable content of interstitial elements (oxygen, nitrogen, hydrogen, carbon, iron).
Grade 1: Has the lowest impurity levels among CP titanium grades. It is the purest, with tighter controls on oxygen and iron.
Grade 2: Contains slightly higher levels of oxygen and iron compared to Grade 1. This small increase in impurities is responsible for its higher strength.
2.Mechanical Properties
Regarding mechanical properties, Grade 1 has lower tensile and yield strength, with a minimum tensile strength of typically 240 MPa (35 ksi) and a minimum yield strength of about 170 MPa (25 ksi). However, it has the highest ductility and formability among all CP titanium grades, making it extremely suitable for severe cold forming processes. Grade 2, on the other hand, has significantly higher strength, with a minimum tensile strength of 345 MPa (50 ksi) and a minimum yield strength of 275 MPa (40 ksi), while still maintaining good ductility, though its formability is slightly lower than that of Grade 1, and its hardness is also higher than Grade 1.
3. Corrosion Resistance
Both grades offer excellent and comparable corrosion resistance in most environments, including seawater, oxidizing acids, and chlorides. Since they are both unalloyed titanium, their passive oxide layer provides superior protection, and the minor difference in purity does not create a meaningful gap in corrosion performance for standard applications.
4. Weldability
Both grades are readily weldable using standard techniques (GTAW/TIG, etc.) with proper inert gas shielding.
Grade 1 is often preferred as a filler metal for welding Grade 2 or other titanium alloys due to its extremely high ductility, which helps mitigate the risk of weld cracking.
Grade 2 is also weldable and is often welded to itself using Grade 1 or Grade 2 filler.
5. Typical Applications
The choice between the two is driven by the required strength and formability:
Grade 1: Used for applications requiring maximum formability and ductility where strength requirements are minimal. Examples include deep-drawn parts, heat exchangers, condenser tubes, and architectural panels.
Grade 2: The "workhorse" of CP titanium. It offers an optimal balance of formability, strength, and cost. It is the most widely used grade for general-purpose applications such as piping, valves, marine hardware, chemical processing equipment, and aerospace components.
In summary, Grade 1 is the purest, softest, and most formable, while Grade 2 is stronger and more commonly used for general industrial applications.
