ASTM B348 Titanium Bar, Rod and Billet: Complete Specification Guide | Grade 1-5, 7, 12

Published by Engineering Team, Shaanxi Qianyi Tuoda Technology Co., Ltd on 2026-10-27

ASTM B348 Titanium Bar, Rod and Billet: Complete Specification Guide

Reviewed by the Engineering Team, Shaanxi Qianyi Tuoda Technology Co., Ltd.

1. Scope and Coverage

ASTM B348 covers titanium and titanium alloy bar, rod, and billet for general industrial applications including machining, forging, fastener manufacture, and structural components. This is the foundational material standard for titanium bar stock — the feedstock from which flanges, fittings, shafts, fasteners, and custom-machined parts are produced.

The standard applies to commercially pure titanium (Grades 1, 2, 3, 4) and alloy grades (Grades 5, 6, 7, 9, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38). For industrial procurement, Grades 1, 2, 3, 4, 5, 7, 9, 12, and 23 represent over 95% of orders.

B348 defines chemical composition, tensile properties, straightness, dimensional tolerances, and certification requirements. It does not cover:

• Forgings (ASTM B381 — requires forging reduction ratio and grain flow control)
• Fasteners (ASTM F467/F468 — additional requirements for thread form and tensile per diameter)
• Medical implants (ASTM F67/F136 — tighter chemistry, lower interstitial limits)
• Welding wire (ASTM B863 — different surface and cleanliness requirements)

Critical distinction: B348 is for bar and billet as feedstock. A bar ordered to B348 is raw material, not a finished component. For flanges and pressure-bearing parts, the bar must be forged per B381 — buying a B348 bar and machining it into a flange shape does not make it a forged flange. This distinction is the single most common procurement failure in titanium bar purchasing.

2. Grade Selection by Application

Cost index relative to Gr2 bar; actual pricing varies with alloy surcharges (Pd, Mo, V, Al) and order volume.

3. Chemical Composition

ASTM B348 Table 1 lists composition limits. For the dominant industrial grades:

Procurement note: For Grade 5, the Al and V ranges are tightly controlled — a bar outside 5.5–6.75% Al or 3.5–4.5% V cannot be certified to B348 even if all other elements are within spec. For Grade 7, the Pd content is the only difference from Grade 2; always request PMI verification on Gr7 bar, especially for fastener and shaft applications where corrosion failure is costly.

4. Mechanical Properties

Values per ASTM B348-21. Yield strength measured at 0.2% offset; elongation and reduction of area on 50mm gauge length.

Key observation for bar buyers: Grade 5 is in an entirely different strength class — 895 MPa tensile vs 345 MPa for Gr2/Gr7. The trade-off is machinability (Gr5 is significantly harder to machine, requires lower speeds, rigid tooling, and flood coolant) and cost (2x Gr2). For fastener applications where Gr2 is too weak but Gr5 is over-specified, Grade 12 (483 MPa) is the intermediate option.

5. Dimensional Tolerances

B348 defines tolerances for round, square, rectangular, and hex bar. For procurement, round bar tolerances are the most frequently specified:

Straightness: 0.5mm per 300mm of length, or 1.5mm total deviation over any 3m length, whichever is more restrictive.

Length tolerance: +6mm / −0 for cut lengths up to 3m; +12mm / −0 for lengths 3–6m; +25mm / −0 for lengths over 6m.

Critical procurement note: B348 tolerances are the minimum. For precision machining (CNC), buyers commonly specify h9 or h11 tolerance bands which are tighter than B348 standard. [FILL: your shop's actual diameter control per tolerance class, e.g. "h9 on Ø10-50mm, h11 on Ø50-125mm"]

6. Bar vs Rod vs Billet vs Forging Stock

B348 covers three product forms that are often confused in procurement:

Why this matters: A buyer who orders "B348 Grade 2 bar" expecting to machine it into a pressure-flange hub gets a non-code part if the bar is not subsequently forged per B381. The procurement document must distinguish between "bar for machining" (B348, final part) and "bar for forging" (B348 feedstock → B381 finished forging). [FILL: your available billet sizes and forging reduction ratios]

7. Procurement Checklist: How to Write a B348 PO

A complete purchase order citing ASTM B348 should include all eight fields:

1. Standard + grade: "ASTM B348 Grade 2 (UNS R50400)" or "ASTM B348 Grade 5 (UNS R56400)"
2. Form: Bar (round/square/hex), rod (coil or straight), or billet
3. Dimensions: Diameter × length (for bar/rod) or cross-section × length (for billet)
4. Condition: Annealed (standard), stress-relieved, or hot-rolled as-forged
5. Tolerance class: Standard B348 or tighter (h9, h11, or specified ± value)
6. Surface finish: Black (as-rolled), pickled, ground, or machined
7. Testing: Tensile per heat, PMI for Gr7/Gr12, UT for billet, macro-etch for forging stock
8. Certification: EN 10204 3.1 MTR minimum; 3.2 if required. Heat number traceability mandatory.

Common failure: Specifying "B348 titanium bar" without grade, diameter, length, or condition. The supplier can legally deliver any grade in any condition. Always complete all eight fields.

Additional fields for critical service:

• Ultrasonic examination (per ASTM A388 or AMS 2630 for billet/large bar)
• Macro-etch grain flow verification (for forging stock)
• Hardness testing (Brinell or Rockwell, per application requirement)
• Cut-to-length tolerance (tighter than standard B348 if required for CNC nesting)

8. Frequently Asked Questions

This guide is maintained by the Engineering Team at Shaanxi Qianyi Tuoda Technology Co., Ltd. Data sourced from ASTM B348-21. For procurement support, contact sales@sxqytd.com.