ASTM B348 Grade 3 Titanium Bar
- Standard: ASTM B348
- Grade: Grade 3 (Commercially Pure Titanium)
- UNS: R50550
- Condition: Annealed
- Dia: φ7 ~ φ300 mm
- Typical Industrial Bar Length: 200–3000 mm
Customizable sizes are available, while specific product parameters should be confirmed per the applicable standard edition and order.
Product Overview
ASTM B348 Grade 3 titanium bar is an unalloyed, commercially pure titanium bar produced and tested to ASTM B348/B348M. Its UNS designation is R50550. Material performance is developed by controlling oxygen, iron, nitrogen, carbon and hydrogen, together with hot working, annealing and grain condition.
Grade 3 is a medium-high-strength commercially pure titanium grade. It is stronger than Grades 1 and 2 while retaining better ductility, formability and processing adaptability than Grade 4. This balance makes Grade 3 suitable for engineering parts requiring increased load capacity together with good weldability and corrosion resistance.
Grade 3 bar is used for corrosion-resistant fasteners, shafts, valve stems, flanges, connectors, electrode components and heat-exchanger parts in chemical processing, desalination, marine, chlor-alkali, electroplating, energy and general industrial equipment.
| Specification | Details |
| Industrial Standard | ASTM B348 |
| Industrial Grades | Gr3 |
| Diameter Range | Ø7 – Ø300 mm |
| Typical Diameters | Ø7, 8, 10, 12, 14, 16, 18, 20, 25, 30, 35, 40, 45, 50, 60, 70, 80, 90, 100, 120, 150, 200 mm |
| Typical Industrial Bar Length | 200–3000 mm; cut-to-length available |
| Surface / Supply Condition | Hot-rolled black surface / Turned / Ground |
| Precision Tolerance | h6 / h7 / h8 available subject to diameter, finishing process and order confirmation |
Main Characteristics
- Balanced strength and ductility: The room-temperature minimum tensile strength is 450 MPa and minimum specified elongation is 18%, supporting moderate-strength applications with useful plasticity.
- Excellent corrosion resistance: A continuous, adherent titanium-oxide passive film forms naturally and can repassivate when oxygen or moisture is present.
- High strength-to-weight potential: Density is approximately 4.51 g/cm³, substantially below that of ordinary steel.
- Good hot and cold workability: Grade 3 may be forged, rolled, extruded, drawn, bent, stamped, spun and machined.
- Good weldability: TIG, MIG, plasma, laser and electron-beam processes may be used with complete inert-gas protection of all hot metal.
- Good low-temperature behavior: CP titanium retains useful ductility and toughness at low temperatures.
- Essentially non-magnetic: This can be useful in equipment sensitive to magnetic response.
- Not significantly strengthened by conventional heat treatment: Annealing is used mainly for stress relief, ductility recovery and microstructural stabilization.
Chemical Composition
ASTM B348 Grade 3 chemistry is controlled to the following mass-percent limits:
| Element | ASTM B348 Grade 3 requirement |
| Nitrogen, N | ≤0.050% |
| Carbon, C | ≤0.080% |
| Hydrogen, H | ≤0.015% |
| Oxygen, O | ≤0.350% |
| Iron, Fe | ≤0.300% |
| Residual elements, each | ≤0.100% |
| Residual elements, total | ≤0.400% |
| Titanium, Ti | Balance |
- Technical references: ASTM B348/B348M and TIMETAL 65A, a material corresponding to ASTM Grade 3.
- Oxygen and iron: Important strength-controlling elements in CP titanium; higher levels generally increase strength and hardness but may reduce ductility and formability.
- Hydrogen: Must be controlled because excessive pickup can form brittle hydrides and increase embrittlement risk.
- Titanium content: ASTM states Titanium: Balance. Grade 3 should not be simplified to a fixed claim such as “Ti ≥99.5%.”
- Lot acceptance: Final chemistry shall be confirmed by the original mill test report for the applicable heat.
Mechanical Requirements
The following room-temperature tensile requirements apply to annealed ASTM B348 Grade 3 bar. The specified edition, dimensions, specimen form and test orientation must also be considered for formal acceptance.
| Property | Requirement | Status |
| Ultimate tensile strength, Rm | ≥450 MPa | ASTM minimum |
| 0.2% offset yield strength, Rp0.2 | ≥380 MPa | ASTM minimum |
| Elongation in the specified gauge length | ≥18% | ASTM minimum |
| Reduction of area | ≥30% | ASTM minimum |
Typical Room-Temperature Properties (Not Guaranteed)
| Property | Reference Value |
| Ultimate tensile strength | Approx. 585 MPa |
| 0.2% offset yield strength | Approx. 450 MPa |
| Elongation | Approx. 25% |
| Reduction of area | Approx. 48% |
| Elastic modulus | Approx. 105–120 GPa |
| Typical bend radius | Approx. 2.5T, dependent on condition and thickness |
Important: Typical data are not ASTM acceptance values and are not automatically guaranteed for every lot. Hardness is not a universal core acceptance criterion for ASTM B348 Grade 3. If hardness, fatigue or bend performance is required, it should be stated separately in the purchase order.
HTN Supply and Quality Services
ASTM B348 Grade 3 titanium bar is produced by evaluated, qualified mill resources. HTN confirms technical requirements from customer drawings and purchase specifications, selects a mill with the appropriate capability, reviews the original MTR and heat/lot records, and verifies the relationship among the material standard, dimensions, quantity, condition and inspection documents.
When agreed in the contract, HTN can coordinate independent retesting, ultrasonic examination, PMI, cut-to-length service, turning or grinding, EN 10204 3.1 documentation and third-party inspection, together with export packing, shipping documents and international delivery.
Typical Applications
- Shafts, valve stems, flanges, fasteners and connectors for chemical equipment;
- Components for heat exchangers, condensers, evaporators and reactors;
- Desalination, shipboard and marine-engineering equipment;
- Pump shafts, supports and corrosion-resistant machined parts;
- Chlor-alkali, electroplating and electrochemical equipment;
- Petrochemical, energy and general industrial equipment;
- Non-high-strength aircraft brackets, duct accessories and secondary structures;
- Engineering parts requiring a balance of light weight, corrosion resistance and moderate strength.
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Fabrication and Processing Characteristics
Machining
Grade 3 can be turned, milled, drilled, ground and threaded. Because titanium has low thermal conductivity, noticeable elastic recovery and a tendency to gall, sharp rigid tools, low cutting speed, stable feed and abundant non-chlorinated cutting fluid are recommended. Dwell and rubbing should be avoided.
Cold forming
Grade 3 can be bent, stamped, drawn and spun, but its higher strength and work hardening reduce cold-forming latitude compared with Grade 2. Greater bend radii, staged forming, intermediate annealing or hot sizing may be required for complex parts.
Hot working
Hot forging, rolling, extrusion and pressing may be used. Temperature, soak time, reduction and atmosphere should follow a qualified procedure to limit abnormal grain growth, surface oxidation and alpha-case formation.
Welding
Grade 3 has good weldability. The weld pool, face, root and hot heat-affected zone must be fully protected by high-purity inert gas to prevent oxygen, nitrogen and hydrogen contamination.
Wear resistance
Unalloyed titanium tends to gall and smear and is not recommended for high-friction sliding pairs without an appropriate coating, surface treatment, bushing or mating-material design.
Machining safety: Fine titanium chips and powders are combustible. They must be collected, stored and handled away from ignition sources in accordance with applicable fire and occupational-safety requirements.
Typical Physical Properties
The following are typical reference values near room temperature and are not mandatory lot-acceptance requirements of ASTM B348:
| Physical property | Typical value |
| Density | Approx. 4.51 g/cm³ |
| Elastic modulus | Approx. 105–120 GPa |
| Specific heat at room temperature | Approx. 0.52 J/(g·K) |
| Thermal conductivity | Approx. 21.8 W/(m·K) |
| Electrical resistivity | Approx. 0.54 μΩ·m |
| Mean CTE, 20–100°C | Approx. 8.6×10⁻⁶/K |
| Mean CTE, 20–300°C | Approx. 9.5×10⁻⁶/K |
| Beta transus | Approx. 920°C |
| Melting range | Approx. 1650–1670°C |
| Poisson’s ratio | Approx. 0.34 |
| Magnetism | Generally regarded as non-magnetic |
Physical-property references: TIMETAL 65A and Carpenter Technology CP Titanium data. Values vary with temperature, heat, orientation and processing condition.
Corrosion Resistance
The corrosion resistance of Grade 3 titanium bar is based on a continuous, tightly adherent passive titanium-oxide film. If the film is slightly damaged, it generally reforms when oxygen or moisture is available.
Environments in Which Grade 3 Generally Performs Well
- Natural seawater, marine atmospheres, salt spray and flowing seawater;
- Neutral chlorides, brines and many chloride-bearing aqueous solutions;
- Nitric acid and many oxidizing acid environments;
- Wet chlorine and hydrated halogen environments where sufficient moisture is present;
- Many alkaline solutions, organic compounds and aqueous salt solutions;
- Desalination, heat-exchange, chlor-alkali and electroplating service.
Environments Requiring Careful Evaluation
- Hot, concentrated or oxygen-starved strongly reducing acids;
- Tight crevices and deposits in hot concentrated chloride or sulfate solutions;
- Fluoride-bearing media or hydrofluoric acid;
- Anhydrous methanol or halide-contaminated methanol;
- Red fuming nitric acid and molten chloride salts;
- Liquid mercury, cadmium and related special environments;
- Completely dry chlorine service;
- Pickling, cathodic protection or electrochemical conditions that may promote hydrogen pickup.
Engineering caution: Corrosion behavior depends on concentration, temperature, pH, aeration, velocity, impurities, crevices, deposits, residual stress, surface condition and dissimilar-metal contact. Product literature supports preliminary material selection but cannot replace corrosion testing and engineering review under the actual service conditions.
Typical Industry Manufacturing Route for Grade 3 Titanium Bar
- Raw-material preparation: Select qualified titanium sponge and approved clean revert, controlling oxygen, iron, nitrogen, carbon, hydrogen and foreign contamination.
- Electrode preparation: Compact the charge into electrode blocks and assemble a melting electrode while excluding oil, moisture and iron-bearing foreign matter.
- Vacuum melting and ingot production: Use VAR, electron-beam cold-hearth melting or another approved titanium melting route. The route and number of melts follow the qualified mill process and purchase requirements.
- Ingot conditioning and chemistry: Crop, peel or grind the ingot as necessary, complete the required chemical analysis and retain clear heat identification.
- Breakdown forging: Upset, draw or multi-directionally forge the ingot to break down the cast structure, improve internal uniformity and produce billet for further working.
- Bar formation: Forge, hot roll, extrude, draw or combine processes to produce the required section. Precision small bars may be turned or centerless ground.
- Heat treatment: Anneal to reduce residual stress, improve uniformity and obtain the required strength-ductility balance. The actual temperature and hold time follow the qualified procedure.
- Surface conditioning: Turn, grind, blast, pickle or combine processes to remove scale and alpha case. Pickling must be controlled to limit hydrogen pickup.
- Straightening and finishing: Straighten, cut, chamfer, turn, grind or polish to achieve the specified diameter, length, straightness and surface quality.
- Final inspection: Verify chemistry, room-temperature tensile properties, dimensions, tolerances, straightness, surface condition and product identification.
- Documentation and traceability: Maintain the relationship among the physical material, labels, heat number, lot, dimensions and original mill test report.
- Packing and delivery: Protect the finished surface and use suitable export packing and transport markings to prevent impact, scratching, moisture and dissimilar-metal contamination.
Melting and inspection note: ASTM B348 does not prescribe a fixed double- or triple-VAR route for every Grade 3 bar. UT, PT, PMI, microstructure, hardness, EN 10204 3.1 and third-party inspection must be ordered when required.
