Titanium Grade 2 (Commercially Pure)
UNS R50400 – Comprehensive technical specification for Canadian aerospace, chemical, marine & medical fabrication. Covers stock sizes, mechanical properties, machinability guidelines, common defects, and storage protocols.
Material Overview & Common Uses
Titanium Grade 2 (UNS R50400) is a commercially pure (CP) alpha-phase titanium alloy with a minimum titanium content of 99.2% by weight. It offers an excellent balance of corrosion resistance, moderate strength, and high ductility, making it the most widely used CP titanium grade.
In Canadian industrial applications, Grade 2 is specified for environments requiring resistance to seawater, chlorides, and oxidizing acids. Common uses include: chemical processing equipment (heat exchangers, vessels, piping), marine components (propeller shafts, hull fittings), aerospace non-structural parts (ducting, fairings), medical implants, surgical instruments, architectural cladding, and heat exchanger tubing.
Its weldability and formability are superior to higher-strength titanium alloys like Grade 5 (Ti-6Al-4V). Typical supply forms include sheet, plate, bar, rod, tube, and wire per ASTM B265 and ASTM B348.
Core Technical Properties & Sizing
| Property | Specification / Value |
|---|---|
| Chemical Composition | Ti ≥99.2%, Fe ≤0.30%, O ≤0.25%, C ≤0.08%, N ≤0.03%, H ≤0.015% |
| Mechanical Properties (Annealed) | Tensile 345–450 MPa, Yield 275–410 MPa, Elongation ≥20% |
| Physical Properties | Density 4.51 g/cm³, Melting 1660–1670°C, Thermal Conductivity 16.4 W/m·K |
| Standard Sheet/Plate Sizes | 48″×120″, 48″×144″. Thickness: 0.020″ to 0.250″ (Sheet), up to 2″ (Plate) |
| Standard Bar/Rod Sizes | Diameters 0.125″ to 12″ in 12′ random lengths. Hex and square bar available. |
| Tolerances (ASTM B265) | Thickness: ±0.005″ (<0.125″), Width: +0.125″/-0″, Flatness: 0.5% of length |
| Surface Finish | Mill finish (2B/2D), pickled, or brushed. Medical/Aerospace per AMS 4901 or ASTM F67. |
Machinability, Tooling & Feeds
| Machining Parameter | Recommendation / Value |
|---|---|
| Machinability Rating | ~30% of free-machining steel |
| Tooling (HSS) | Sharp, positive rake (M42, T15). Speeds: 30–60 SFM (9–18 m/min) |
| Tooling (Carbide) | C2 or C3 grade. Speeds: 80–150 SFM (24–46 m/min) |
| Feeds (Turning) | 0.002–0.008 in/rev (0.05–0.20 mm/rev) |
| Feeds (Milling) | 0.001–0.004 in/tooth (0.025–0.10 mm/tooth) |
| Depth of Cut | Roughing: 0.020–0.100 in (0.5–2.5 mm). Finishing: 0.005–0.020 in (0.13–0.50 mm) |
| Coolant | High-pressure flood (≥100 psi), water-soluble oil or synthetic coolant |
| Drilling | Split-point or parabolic flute, 118°–135° point angle, peck cycle (0.020–0.050 in/peck) |
| Tapping | Spiral-point or roll-form taps; thread-mill for threads >0.5″ |
| Sawing | Bi-metal blades, 4–6 TPI, 80–120 SFM, heavy feed |
| Grinding | Silicon carbide wheels (C-46-H-V), light passes, copious coolant |
| Welding (GTAW) | Argon shielding, ERTi-2 filler wire, no preheat required |
| Forming (Bend Radius) | Minimum 2T (sheet <0.063″), 3T (thicker). Moderate springback. |
Common Defects & Quality Control
| Defect | Description | Detection Method |
|---|---|---|
| Alpha Case | Oxygen-enriched brittle layer from hot working; blue-white discoloration | Microhardness testing, visual inspection |
| Surface Contamination | Embedded iron or carbon steel particles causing localized corrosion | Ferroxyl test, magnetic particle inspection |
| Laminations | Internal separations in sheet/plate from rolling | Ultrasonic testing (UT) per ASTM E2375 |
| Porosity | Gas pockets in welds or castings | Radiography (RT), Dye penetrant (PT) |
| Cracking | Stress corrosion cracking (SCC) in chloride environments | PT, Eddy current (ET) |
| Dimensional Non-conformance | Thickness, width, or length out of tolerance | Calipers, micrometers, tape measure |
| Surface Scratches / Dents | Depth must not exceed 10% of thickness for critical applications | Visual inspection, depth gauge |
| Work Hardening | Improper machining leads to chatter, poor finish, and tool wear | Portable hardness tester |
QC Protocol: Incoming inspection per ASTM B265 or B348 – verify mill certificate, perform visual and dimensional checks, conduct PT on critical surfaces, and UT for thickness >0.125″ if required.
Storage, Handling & Racking Guidelines
| Aspect | Guideline |
|---|---|
| Environment | Indoors, clean, dry (10–30°C, humidity <60% RH). Away from welding or grinding areas. |
| Contamination Prevention | Keep away from carbon steel, iron, and copper. Use dedicated titanium racks or plastic-lined bins. |
| Sheet/Plate Racking | Store flat on wooden pallets or steel racks with rubber pads. Max stack: 24″ (<0.125″), 36″ (thicker). |
| Bar/Rod Racking | Horizontal in V-racks or on wooden dunnage. Support every 3 ft (1 m) to prevent sagging. |
| Handling | Use clean cotton or nitrile gloves. Lift sheets with suction cups or padded clamps. Never drag or slide. |
| Long-term Storage (>6 months) | Apply light oil or protective film (e.g., LPS 3) to machined surfaces. |
| Inspection Frequency | Quarterly for corrosion, contamination, or mechanical damage. FIFO rotation strictly implemented. |