Overview: The essential difference between GR2 and GR5 titanium tubes
In the field of industrial titanium tubes, GR2 (Grade 2) and GR5 (Grade 5, i.e.， Ti-6Al-4V) are the two most commonly used materials. Their core differences lie in composition and mechanical properties. GR2 is pure titanium (α type), while the GR5 titanium tube is a titanium alloy (α+β type) containing 6% aluminum and 4% vanadium. This difference in composition directly leads to their different performances in corrosion resistance, strength, machinability, etc.
1. Mechanical properties comparison
1. Strength characteristics
GR2 titanium tube:
Tensile strength: ≥345 MPa
Yield strength: ≥275 MPa
Elongation: ≥20%
GR5 titanium tube:
Tensile strength: ≥895 MPa (2.6 times that of GR2)
Yield strength: ≥828 MPa (3 times that of GR2)
Elongation: ≥10%
Engineering significance: GR5's significantly higher strength makes it the first choice for aerospace, military, and other fields with demanding weight-to-strength ratios, while GR2 is more suitable for general industrial applications.
2. Hardness and wear resistance
GR5's hardness (HV≈340) is significantly higher than GR2's (HV≈160), and it has better wear resistance, but the processing difficulty is correspondingly greater.
2. Corrosion resistance analysis
1. Common advantages
Both have typical corrosion resistance characteristics of titanium:
Excellent seawater corrosion resistance
Good chloride stress corrosion resistance
Strong resistance to oxidizing media such as nitric acid and chromic acid
2. Key differences
GR2: Slightly better performance in reducing environments (such as dilute hydrochloric acid and sulfuric acid)
GR5: Better stability in high temperature (>300℃) corrosive environments
Special note: GR5 may be more sensitive to the presence of aluminum in fluorine-containing environments
3. Process performance comparison
1. Formability
GR2:
Excellent cold forming ability
Complex bending and forming can be performed
Excellent welding performance (ERTi-2 welding wire is recommended)
GR5:
Good hot forming performance (optimal processing temperature 700-850℃)
Limited cold forming performance, prone to springback
Welding requires strict control (ERTi-5 welding wire is recommended)
2. Machinability
GR5 is significantly more difficult to machine than GR2, requiring:
Lower cutting speed (about 30-50% of GR2)
Specialized tool geometry
Sufficient cooling and lubrication
4. Differences in temperature adaptability
Working temperature range:
GR2: Recommended long-term working temperature ≤300℃
GR5: Can be used in a 400℃ environment for a long time (up to 600℃ in the short term)
In a low temperature environment (such as -196℃), both show good toughness, but GR5 has a more obvious strength advantage.
5. Cost and economic analysis
- Material cost: GR5 is usually 1.5-2 times more expensive than GR2
- Processing cost: GR5 has higher machining and hot forming costs
- Life cycle cost: GR5 may be more economical in high temperature and high stress environments
Conclusion:
There is no best, only the most suitable
GR2 and GR5 titanium tubes each have their irreplaceable advantages:
Choose GR2: When excellent formability, weldability, and economy are required
Choose GR5: When facing high strength, high temperature, or special working conditions
