1. Classification & Core Identity
Grade 3 Titanium: Belongs to the commercial pure titanium (CP Ti) family (ASTM Grade 1–4). It contains >99% titanium, with only trace amounts of impurities (e.g., oxygen, iron) to adjust basic properties. Its performance is primarily determined by the purity of titanium and minor impurity content.
Grade 5 Titanium: Classified as a α+β titanium alloy, with the industry-standard designation Ti-6Al-4V (meaning it contains ~6% aluminum and ~4% vanadium, with the remainder being titanium). The addition of aluminum (strengthens the α phase) and vanadium (stabilizes the β phase) fundamentally alters its microstructure and mechanical properties, making it far stronger than pure titanium grades.
2. Chemical Composition
3. Mechanical Properties
4. Corrosion Resistance
Grade 3 Titanium: Offers superior general corrosion resistance in mild to moderate environments (e.g., seawater, dilute acids, atmospheric conditions). Its pure titanium matrix forms a dense, stable oxide layer (TiO₂) that prevents further oxidation, making it ideal for chemical processing or marine components where "pure" corrosion protection is critical.
Grade 5 Titanium: Has good corrosion resistance in most environments (e.g., aerospace fuels, physiological fluids), but is slightly less resistant than Grade 3 in highly aggressive media (e.g., concentrated acids like sulfuric acid). Its corrosion performance is a trade-off for enhanced strength-still sufficient for most industrial/aerospace needs, but not the first choice for extreme chemical exposure.
5. Processing & Fabrication
Grade 3 Titanium: Easier to fabricate. Its high ductility allows for cold working (e.g., rolling, bending, drawing) and welding (with minimal risk of cracking) without complex pre/post-heat treatments. It also machines more smoothly than Grade 5, reducing tool wear.
Grade 5 Titanium: Harder to process. Its high strength and lower ductility require hot working (processing at elevated temperatures, ~800–900°C) for forming, as cold working may cause cracking. Welding demands precise control (e.g., argon shielding, post-weld heat treatment) to avoid brittleness. Machining is also more challenging (high cutting forces, rapid tool wear) and requires specialized tools (e.g., carbide inserts).
6. Application Scenarios
Chemical processing equipment (e.g., tanks, pipes, valves for dilute acids).
Marine components (e.g., hull fasteners, heat exchangers).
Medical devices (e.g., surgical instruments, non-load-bearing implants).
Architectural cladding (for durability in harsh weather).
Aerospace/aviation (e.g., aircraft landing gear, engine components, structural frames).
Automotive (e.g., high-performance engine parts, racing vehicle components).
Medical implants (e.g., hip/knee replacements, dental implants-combines strength with biocompatibility).
Sports equipment (e.g., bicycle frames, golf club heads).
