Titanium Grade 3 · UNS R50550 · W. Nr. 3.7055
Titanium Grade 3 (R50550): composition, properties, fittings and flanges
Titanium Grade 3 (R50550, W. Nr. 3.7055) is Commercially pure titanium, medium-high strength grade. Titanium Grade 3 is specified at Titanium Balance. Grade 3 sits between Grade 2 and Grade 4: higher oxygen lifts strength to 450 MPa while keeping the corrosion resistance, formability and weldability of unalloyed titanium.…
- UNS
- R50550
- W. Nr.
- 3.7055
- Density
- 4.51 g/cm³ (0.163 lb/in³)
- Key strength
- 450 MPa / 65 ksi
Identification and standards
| Short form | Titanium Grade 3 · UNS R50550 · W. Nr. 3.7055 |
|---|---|
| Classification | Commercially pure titanium, medium-high strength grade |
| UNS | R50550 |
| Werkstoff number | 3.7055 |
| Material family | Titanium Alloys |
Chemical composition
| Element | Composition (wt %) | Why it is there |
|---|---|---|
| Titanium (Ti) | Balance | Matrix |
| Oxygen (O) | 0.35 max | Interstitial strengthening |
| Iron (Fe) | 0.30 max | Controlled for corrosion resistance |
| Carbon (C) | 0.08 max | - |
| Nitrogen (N) | 0.05 max | - |
| Hydrogen (H) | 0.015 max | Hydride control |
| Other elements, each | 0.10 max | - |
| Residual balance | Remainder | - |
Note Single figures are maximum limits unless shown as a range. Always confirm against the heat-specific EN 10204 3.1 certificate supplied with your order.
Mechanical properties
| Tensile strength, min (annealed) | 450 MPa / 65 ksi |
|---|---|
| 0.2 % yield strength, min | 380 MPa / 55 ksi |
| Elongation in 2 in, min | 18 % |
| Typical hardness, annealed | 150 - 200 HB |
| Pressure vessel design allowable | Higher than Grade 2 at the same temperature |
Warning Values depend on product form, section thickness and heat treatment. Larger sections generally achieve lower strength than thin product; always design against the applicable code allowable stress rather than these figures.
Physical properties
| Density | 4.51 g/cm³ (0.163 lb/in³) |
|---|---|
| Melting range | 1668 °C (3034 °F) |
| Modulus of elasticity | 103 GPa (15.0 x 10⁶ psi) |
| Thermal conductivity at 20 °C | 16.4 W/m·K |
| Mean coefficient of thermal expansion, 20-100 °C | 8.6 µm/m·°C |
| Specific heat capacity | 523 J/kg·K |
Specifications by product form
| Forgings & flanges | ASTM B381 Grade F-3 · ASME SB-381 |
|---|---|
| Butt weld fittings | ASTM B363 WPT-3 · ASME SB-363 |
| Seamless pipe & tube | ASTM B861 / B338 Grade 3 |
| Plate / sheet / strip | ASTM B265 Grade 3 · ASME SB-265 |
| Bar / rod | ASTM B348 Grade 3 |
| Welding consumables | ERTi-3 with full inert gas shielding |
| UNS / EN / China | UNS R50550 · W. Nr. 3.7055 · GB TA3 |
Product forms available
Hangbo supplies this grade in the following forms. Sizes outside the listed range can often be produced to order.
- Forged flanges blanks and finished flanges to ASME B16.5, B16.47 Series A/B and B16.36
- Butt weld elbows, tees, reducers, caps and stub ends to ASME B16.9 and MSS SP-43
- Seamless pipe and tube to the applicable ASTM / ASME pipe specification
- Forged rings, discs and hubs machined to your drawing
Typical applications
- Pressure vessels and heat exchangers needing higher allowable stress
- Chemical process columns, reactors and piping
- Airframe and marine hardware with weight targets
- Chlor-alkali and chlorine dioxide plant components
Welding, forming and machining
- Welding
- Weld with ERTi-3 filler under full argon shielding including back purge. Avoid iron contamination from tooling, which creates local corrosion cells.
- Heat treatment
- Anneal at 650 - 760 °C and cool in still air; stress relieve at 480 - 595 °C.
- Hot and cold forming
- Hot work in the range stated by the mill for this grade, then re-solution or re-age before final machining so that the delivered condition matches the certificate.
- Machining
- Machine with sharp carbide or high-speed steel tooling, positive rake, constant feed and ample coolant. Never dwell - the surface work-hardens quickly.
Buy Titanium Grade 3 from Hangbo
Material is supplied with full heat-number traceability, solution annealing or ageing performed under calibrated furnace control, and an EN 10204 3.1 certificate covering chemical analysis, mechanical properties, heat treatment records and the agreed NDT scope. Positive material identification and third party inspection and test reports from SGS are available for critical service.