ASTM B348 — Titanium Bars and Billets Standard
Complete guide to ASTM B348 specification for titanium and titanium alloy bars and billets. Grades covered, chemical composition, mechanical properties, and certification requirements for round, square, and hexagonal bar stock.
Quick Answer
What is ASTM B348?
ASTM B348 is the international specification for titanium and titanium alloy bars and billets. It covers the chemical composition, mechanical properties, dimensional tolerances, and testing requirements for round, square, hexagonal, and octagonal bar stock as well as billet forms. ASTM B348 is the most commonly referenced standard for titanium bar used in CNC machining, forging, and medical implant manufacturing.
Scope
ASTM B348 covers titanium and titanium alloy bars and billets in the following conditions: annealed, cold-worked, and heat-treated. The standard applies to diameters and cross-sections from 4.8 mm (0.188 in) up to 254 mm (10.000 in) for bars, and larger for billets.
Key parameters covered:
- Diameter/Cross-section: 4.8 mm to 254 mm (bars); larger for billets
- Forms: Round bars, square bars, hexagonal bars, octagonal bars, billets
- Length: Random mill lengths or specified cut lengths
- Condition: Hot-rolled, forged, cold-finished, centreless ground
Key Requirements
Chemical Composition
The standard defines precise limits for interstitial elements (Fe, O, C, N, H) and alloying elements for grades 1 through 38. Composition is verified through mill test reports (MTR) per ASTM E120 or equivalent.
Mechanical Properties
| Property | Requirement |
|---|---|
| Tensile Strength | Grade-dependent (345–1170 MPa) |
| Yield Strength (0.2% offset) | Grade-dependent (275–1100 MPa) |
| Elongation | Grade-dependent (10–24%) |
| Reduction of Area | Grade-dependent (15–35%) |
Dimensional Tolerances
| Diameter Range | Tolerance (Cold-Finished) |
|---|---|
| Up to 12.7 mm | ± 0.05 mm |
| 12.7 – 25.4 mm | ± 0.08 mm |
| 25.4 – 50.8 mm | ± 0.13 mm |
| 50.8 – 101.6 mm | ± 0.20 mm |
Testing Requirements
- Tensile testing — Per ASTM E8/E8M at room temperature
- Flattening test — For hollow bars per ASTM B348
- Ultrasonic inspection — Optional, per ASTM E2375 for critical applications
- Dimensional inspection — Diameter, length, straightness, surface condition
- Surface quality — Free from cracks, seams, laps, and pipe defects
Typical Applications
- Aerospace: Fastener stock, landing gear pins, actuator shafts, engine mounting brackets, hydraulic fittings
- Medical: Orthopaedic implant stems, trauma screws, spinal rods, dental implant abutments, surgical instrument blanks
- Chemical Processing: Valve stems, pump shafts, flanges, pipe fittings, thermowell tubes
- Energy: Downhole tooling components, geothermal probe bodies, subsea connector pins
- Industrial: Bolt stock, threaded fasteners, custom machined components from bar
Related Materials
- Grade 5 Titanium (Ti-6Al-4V) — Most common bar alloy for aerospace and medical applications
- Grade 23 Titanium (Ti-6Al-4V ELI) — Medical implant bar per ASTM F136
- Grade 2 Titanium — CP bar for corrosion-resistant shafts and fittings
- Grade 9 Titanium (Ti-3Al-2.5V) — Weldable bar for hydraulic and structural applications
Related Services
- CNC Machining — Precision milling and turning from bar stock for complex components
- Titanium Turning — High-volume production of cylindrical parts from bar
- 5-Axis Machining — Complex geometry components machined from bar or billet
- Wire EDM — Precision cutting of bar blanks for medical and prototype applications