Titanium’s reputation as a “wonder metal” stems from its unique combination of strength, lightness, and corrosion resistance. However, not all titanium is created equal. Titanium Grade 2 (pure titanium) and Grade 5 (Ti-6Al-4V alloy) are two of the most widely used titanium grades, yet their properties and applications vary drastically. This article provides a comprehensive, technical comparison of these grades, empowering engineers, manufacturers, and designers to make informed material choices.
1. Overview of Titanium Grades - Titanium Grade 2 vs Grade 5
1.1 Titanium Grade 2 (UNS R50400)
Type: Commercially pure (CP) titanium (α-phase structure). Composition: ≥99.2% titanium, with oxygen (≤0.25%), iron (≤0.30%), and carbon (≤0.08%) as primary impurities. Standards: ASTM B265 (sheet/plate), ASTM B338 (tubes).
1.2 Titanium Grade 5 (UNS R56400)
Type: Alpha-beta titanium alloy (Ti-6Al-4V). Composition: 90% titanium, 6% aluminum, 4% vanadium. Standards: ASTM B348 (bars/billets), AMS 4928 (aerospace).
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2. Key Differences: Titanium Grade 2 vs Grade 5
2.1 Chemical Composition
| Element | Grade 2 | Grade 5 |
|---|---|---|
| Titanium (Ti) | ≥99.2% | 90% |
| Aluminum (Al) | – | 6% |
| Vanadium (V) | – | 4% |
| Oxygen (O) | ≤0.25% | ≤0.20% |
| Iron (Fe) | ≤0.30% | ≤0.40% |
2.2 Mechanical Properties
| Property | Grade 2 | Grade 5 |
|---|---|---|
| Tensile Strength | 345–550 MPa (50–80 ksi) | 895–930 MPa (130–135 ksi) |
| Yield Strength | 275–483 MPa (40–70 ksi) | 828–869 MPa (120–126 ksi) |
| Elongation at Break | 20–30% | 10–15% |
| Fatigue Strength | 300 MPa (43.5 ksi) | 500 MPa (72.5 ksi) |
| Hardness | 80–90 HRB | 36–41 HRC |
| Fracture Toughness | 70 MPa√m | 55 MPa√m |
Note: Grade 5’s lower elongation and fracture toughness are offset by its superior strength.
2.3 Corrosion Resistance
Grade 2: Exceptional resistance to chlorides, acids (e.g., nitric, acetic), and seawater. Ideal for chemical processing and marine environments. Grade 5: Slightly reduced corrosion resistance due to alloying elements but still outperforms stainless steel. Avoid in reducing acids (e.g., HCl).
2.4 Temperature Performance
Grade 2: Loses strength above 300°C (572°F). Max service temperature: 400°C (752°F). Grade 5: Retains 80% of room-temperature strength at 450°C (842°F). Used in jet engines and high-temperature exhaust systems.
2.5 Machinability & Weldability
| Process | Grade 2 | Grade 5 |
|---|---|---|
| Machinability | Easy (similar to 304 stainless steel) | Difficult (requires carbide tools, coolants) |
| Weldability | Excellent (TIG, plasma, laser) | Good (post-weld heat treatment needed) |
| Formability | High (ductile) | Limited (prone to springback) |
2.6 Cost Comparison
Grade 2: 40 per kg (lower raw material and processing costs). Grade 5: 150 per kg (costly alloying, thermal treatments, and machining).
3. Industrial Applications - Titanium Grade 2 vs Grade 5
3.1 Titanium Grade 2 Use Cases
Chemical Processing: Reactor vessels, heat exchangers (resistant to sulfuric and nitric acids). Marine Engineering: Ship hulls, offshore rig components, desalination plants. Architecture: Roofing, façades (lightweight and corrosion-proof). Medical: Non-load-bearing implants (e.g., cranial plates, dental abutments).
3.2 Titanium Grade 5 Use Cases
Aerospace: Jet engine fan blades (Boeing 787), airframe fasteners, landing gear. Biomedical: Load-bearing implants (hip stems, spinal rods) using Grade 5 ELI (Extra Low Interstitial). Automotive: Connecting rods (Porsche 911 GT3), high-performance exhaust systems. Energy: Turbine blades for geothermal and nuclear power plants.
4. How to Choose Between Grade 2 and Grade 5
4.1 Decision Matrix
| Requirement | Choose Grade 2 If… | Choose Grade 5 If… |
|---|---|---|
| High Strength | – | ✓ (Critical for structural loads) |
| Corrosion Resistance | ✓ (Aggressive chemical environments) | ✓ (Moderate environments) |
| Budget | ✓ (Cost-sensitive projects) | – |
| High-Temperature Service | – | ✓ (>300°C applications) |
| Biocompatibility | ✓ (Non-load-bearing implants) | ✓ (Load-bearing ELI variants) |
4.2 Hybrid Solutions
Cladding: Grade 2 cladding over Grade 5 substrates for marine hardware (corrosion resistance + strength). Additive Manufacturing: 3D-printed Grade 5 components with Grade 2 coatings for chemical reactors.
5. Limitations and Challenges
5.1 Grade 2 Drawbacks
Low Strength: Unsuitable for load-bearing aerospace or automotive parts. Wear Resistance: Poor compared to hardened steels or ceramics.
5.2 Grade 5 Challenges
Cost: High material and machining expenses limit large-scale adoption. Biological Risks: Vanadium in standard Grade 5 may cause cytotoxicity (solved by Grade 5 ELI).
6. Future Innovations
6.1 Sustainable Production
Grade 2 Recycling: Upcycling scrap from chemical plants into architectural components. Green Grade 5: Hydrogen-assisted direct reduction (HADT) to replace the Kroll process.
6.2 Advanced Alloy Development
Grade 5 + Carbon Nanotubes: Enhanced wear resistance for automotive gears. Grade 2-5 Composites: Additive-manufactured parts combining both grades’ strengths.
Titanium Alloy Strip / Precision Strip
Huaxiao-Alloy supplies medical & aerospace-grade Titanium Alloy Strips (0.05–5.0 mm) with ±0.005 mm tolerance. AS9100D & ISO 13485 certified. Custom slitting, annealing, global delivery. Request samples!
Huaxiao-Alloy manufactures high-performance Titanium Alloy Profiles (ASTM B381/ASME SB381) for aerospace, medical, and energy sectors. AS9100D & ISO 13485 certified. Custom sizes, global delivery, competitive MOQ. Request samples now!
No. Grade 2’s strength can only be improved via cold working (e.g., rolling, forging).
No. Both grades are non-magnetic.
Grade 2, due to its superior corrosion resistance in chloride-rich environments.
Grade 5 ELI (Extra Low Interstitial) minimizes alloying element risks while providing the strength needed for load-bearing implants.
Yes, but it requires specialized techniques like electron beam welding to avoid brittle intermetallic phases.
Titanium Grade 2 vs Grade 5: Full Comparison, Uses, and How to Choose
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