ASTM B381/B381M is the primary standard by ASTM International covering titanium and titanium alloy forgings in all commercially available grades. The specification defines forging-grade designations (F-prefix: F-1, F-2, F-5, F-7, F-12, etc.) with forged-specific mechanical property requirements including reduction of area (RA) — an additional ductility metric critical for forged components. These forgings cover flanges, fittings, valve bodies, and custom shapes for chemical processing, aerospace, marine, and medical industries. The companion specification ASME SB381 is adopted for ASME Code-stamped equipment.
Zhengzhou Huitong (HT Pipe) supplies ASTM B381 / ASME SB381 compliant forgings with full Mill Test Certificates (MTC) per EN 10204 3.1.
1. Standard Scope & Designation
ASTM B381/B381M is the comprehensive specification covering titanium and titanium alloy forgings in all commercially available grades, including commercially pure (CP) titanium forging grades F-1 through F-4, alloy grades F-5 (Ti-6Al-4V), F-7 (Ti-Pd), F-12 (Ti-0.3Mo-0.8Ni), and many specialized aerospace and medical grades.
| Form |
Manufacturing Process |
Size Range |
Typical Thickness/Tolerance |
| Forgings (Flanges, Fittings, Valve Bodies, Custom Shapes) |
Closed-die or open-die forged from billet/bar per standard |
ASTM B381 covers forgings in all standard and custom shapes: flanges (WN, blind, lap joint, socket weld), fittings (elbows, tees, reducers), valve bodies, pump casings, and custom-machined shapes. |
Per standard / purchaser agreement |
Scope Statement (ASTM B381/B381M): "This specification covers titanium and titanium alloy forgings for general corrosion-resistant service and for aerospace, chemical, marine, and medical applications where high strength-to-weight ratio and corrosion resistance are required."
| Designation |
Issuing Body |
Unit System |
Dimension Standard |
Latest Edition |
| ASTM B381 |
ASTM International |
Inch-Pound |
Per forging drawing |
B381/B381M-21 |
| ASTM B381M |
ASTM International |
SI (Metric) |
Per forging drawing |
B381/B381M-21 |
| ASME SB381 |
ASME (BPVC Sec. II Part B) |
Both |
Per forging drawing |
2023 Edition |
2. Grades Covered by ASTM B381
ASTM B381 covers the following grades. Each grade is defined by its UNS number and specific chemistry targeted at different service environments.
| Grade / UNS |
Key Chemistry Requirements |
Mechanical Properties (min) |
| F-1 (CP Ti) |
Grade 1 chemistry: C 0.10, Fe 0.20, O 0.18, N 0.03, H 0.015 |
Annealed: TS ≥ 240 MPa (35 ksi), YS ≥ 170 MPa (25 ksi), El ≥ 24%, RA ≥ 30% |
| F-2 (CP Ti) |
Grade 2 chemistry: C 0.10, Fe 0.30, O 0.25, N 0.03, H 0.015 |
Annealed: TS ≥ 344 MPa (50 ksi), YS ≥ 275 MPa (40 ksi), El ≥ 20%, RA ≥ 30% |
| F-5 (Ti-6Al-4V) |
Al 5.5–6.75, V 3.5–4.5, Fe 0.40, O 0.20, C 0.10 |
Annealed: TS ≥ 895 MPa (130 ksi), YS ≥ 828 MPa (120 ksi), El ≥ 10%, RA ≥ 25% |
| F-7 (CP Ti + Pd) |
Grade 7 chemistry: Pd 0.12–0.25, otherwise same as F-2 |
Annealed: TS ≥ 344 MPa (50 ksi), YS ≥ 275 MPa (40 ksi), El ≥ 20%, RA ≥ 30% |
| F-12 (Ti-0.3Mo-0.8Ni) |
Mo 0.2–0.4, Ni 0.6–0.9, O 0.25, C 0.08 |
Annealed: TS ≥ 483 MPa (70 ksi), YS ≥ 345 MPa (50 ksi), El ≥ 18%, RA ≥ 25% |
3. Chemical Composition
Values are weight percent maximum unless shown as a range. Heat analysis. Per ASTM B381 Table 1.
| Grade |
N (max) |
C (max) |
H (max) |
Fe (max) |
O (max) |
Alloy Additions |
Notes |
| F-1 |
0.03 |
0.10 |
0.015 |
0.20 |
0.18 |
— |
— |
| F-2 |
0.03 |
0.10 |
0.015 |
0.30 |
0.25 |
— |
— |
| F-3 |
0.05 |
0.10 |
0.015 |
0.30 |
0.35 |
— |
— |
| F-4 |
0.05 |
0.10 |
0.015 |
0.50 |
0.40 |
— |
— |
| F-5 |
0.05 |
0.10 |
0.015 |
0.40 |
0.20 |
Al 5.5–6.75, V 3.5–4.5 |
— |
| F-7 |
0.03 |
0.10 |
0.015 |
0.30 |
0.25 |
Pd 0.12–0.25 |
— |
| F-9 |
0.03 |
0.10 |
0.015 |
0.25 |
0.15 |
Al 2.5–3.5, V 2.0–3.0 |
— |
| F-12 |
0.03 |
0.08 |
0.015 |
0.30 |
0.25 |
Mo 0.2–0.4, Ni 0.6–0.9 |
— |
4. Mechanical Property Requirements
All values are minimum requirements. Tensile testing per ASTM E8/E8M.
| Grade / Condition |
Heat Treatment |
TS min MPa (ksi) |
YS min MPa (ksi) |
El min (%) |
RA min (%) |
| F-1 (Gr.1) |
Annealed |
240 (35) |
170 (25) |
24 |
30 |
| F-2 (Gr.2) |
Annealed |
344 (50) |
275 (40) |
20 |
30 |
| F-3 (Gr.3) |
Annealed |
450 (65) |
380 (55) |
18 |
30 |
| F-4 (Gr.4) |
Annealed |
550 (80) |
480 (70) |
15 |
25 |
| F-5 (Gr.5) |
Annealed |
895 (130) |
828 (120) |
10 |
25 |
| F-7 (Gr.7) |
Annealed |
344 (50) |
275 (40) |
20 |
30 |
| F-12 (Gr.12) |
Annealed |
483 (70) |
345 (50) |
18 |
25 |
5. Heat Treatment Requirements
| Grade |
Temperature Range |
Cooling Method |
Purpose |
| F-1, F-2, F-3, F-4 (CP Ti) |
600–760°C (1110–1400°F) |
Air cool or water quench |
Full anneal; dependent on section thickness |
| F-5 (Ti-6Al-4V) |
700–790°C (1300–1450°F) |
Air cool or furnace cool |
Mill anneal for general service; STA optional for max strength |
| F-7 (Ti-Pd) |
600–760°C (1110–1400°F) |
Air cool or water quench |
Same as CP grades; Pd does not affect HT requirements |
| F-12 (Ti-0.3Mo-0.8Ni) |
590–675°C (1100–1250°F) |
Air cool or water quench |
Annealed; higher annealing temperature for larger sections |
| Stress Relief (all) |
480–595°C (900–1100°F) |
Air cool |
1–4 hr soak; reduces residual stress from forging/machining |
6. Testing & Inspection Requirements
| Test |
Requirement |
Reference Standard |
| Chemical Analysis (Heat) |
One per heat; all elements per B381 Table 1 |
ASTM B381 Table 1 |
| Tensile Test |
One per lot; tensile from test forging or prolongation per ASTM E8/E8M |
ASTM E8 / E8M |
| R/A (Reduction of Area) |
All grades; additional ductility metric beyond elongation |
ASTM E8 / E8M |
| Hardness Test |
Optional per agreement; Brinell or Rockwell |
ASTM E10 / E18 |
| Ultrasonic Examination |
Per ASTM B594 or AMS 2631 for aerospace-critical forgings |
ASTM B594 / AMS 2631 |
| Macroetch / Microstructure |
Flow line pattern verification for critical forgings |
ASTM E340 / E407 |
| Visual & Dimensional |
Per forging drawing; tolerance per ASTM B381 or purchaser |
ASTM B381 |
7. Dimensions & Dimensional Tolerances
ASTM B381 covers forgings in all standard and custom shapes: flanges (WN, blind, lap joint, socket weld), fittings (elbows, tees, reducers), valve bodies, pump casings, and custom-machined shapes. Forging size limited only by press capacity — typical Ti forging capability up to ~5000 kg (11,000 lb) for closed-die forgings and larger for open-die. Minimum stock removal per standard unless specified.
8. Industries & Applications
| Industry |
Recommended Grade |
Typical Service Media / Application |
| Chemical Processing |
F-2 / F-7 |
Flanges, valve bodies, pump casings for corrosive media |
| Aerospace |
F-5 (Ti-6Al-4V) |
Engine mounts, structural forgings, landing gear components |
| Marine / Offshore |
F-2 / F-7 |
Subsea flanges, valve bodies, bolting for seawater service |
| Medical Implants |
F-23 (Ti-6Al-4V ELI) |
Orthopedic implant forgings, surgical instrument bodies |
| Desalination |
F-2 |
High-pressure flanges, pump impellers, evaporator components |
| Oil & Gas |
F-5 / F-12 |
Downhole tool bodies, subsea connector forgings, bolting |
9. ASTM B381 vs ASTM B348 (Titanium Bar and Billet — the mill product from which forgings are produced) — Comparison
| Standard |
ASTM B381 (Forgings) |
ASTM B348 (Bar & Billet) |
| Product Form |
Finished or near-net-shape forgings |
Wrought bar, billet, rod (mill product) |
| Grades |
F-1, F-2, F-5, F-7, F-12... (forging grades) |
Grade 1, 2, 5, 7, 12... (wrought mill grades) |
| Mechanical Property Basis |
Test coupon from forging or prolongation |
Test specimen from bar product |
| Additional Requirement |
Reduction of Area (RA) mandatory |
RA not required for all grades |
| Microstructure Control |
Flow line pattern for directional properties |
Not typically specified |
| Typical Application |
Flanges, fittings, valve bodies |
Machined components from bar stock |
Key Distinction: ASTM B381 specifies forgings with directional grain flow optimized for mechanical properties along specific axes — critical for pressure-containing components (flanges, fittings). ASTM B348 covers the wrought bar/billet mill product, which is subsequently forged or machined. Forged Ti components (B381) typically exhibit superior fatigue strength and fracture toughness in the longitudinal direction compared to equivalent machined-from-bar components.
10. Related Standards
| Standard |
Scope |
Relationship |
| ASTM B348 |
Titanium Bar and Billet |
Mill product from which forgings are produced |
| ASTM B861 |
Seamless Titanium Pipe |
Pipe stock; often specified with B381 forged flanges |
| ASTM B265 |
Titanium Plate, Sheet, and Strip |
Plate for fabricated components |
| ASME SB381 |
ASME BPVC Section II Part B |
Identical; code-stamped pressure equipment |
| ASME B16.5 |
Pipe Flanges and Flanged Fittings |
Flange dimension standard for Ti WN, blind, LJ flanges |
| AWS A5.16 |
Titanium Welding Consumables |
ERTi-2, ERTi-5, ERTi-7 filler wires for welding forged components |
| AMS 6931 |
Aerospace Ti-6Al-4V Forgings (Solution Treated & Aged) |
Aerospace supplement for aged F-5 forgings |
| ASTM E8/E8M |
Tensile Testing of Metallic Materials |
Governs tensile, yield, elongation, RA procedure |
11. How to Order — Required Information
| No. |
Item |
Requirement / Example |
| 1 |
Specification |
ASTM B381 / ASME SB381 |
| 2 |
Grade |
F-2 (CP Ti Gr.2), F-5 (Ti-6Al-4V), F-7 (Ti-Pd), F-12 (Ti-0.3Mo-0.8Ni), etc. |
| 3 |
Product Form / Drawing |
Forging type and drawing/pattern number |
| 4 |
Dimensions |
As per forging drawing or standard fitting/flange dimensions |
| 5 |
Condition |
Annealed (standard); STA for F-5 optional |
| 6 |
Test Coupon Location |
Prolongation or separate test forging per agreement |
| 7 |
NDE (optional) |
UT per ASTM B594, PT per ASTM E165, RT when specified |
| 8 |
Certification |
EN 10204 3.1 or 3.2 CMTR with tensile + chemistry |
| 9 |
Quantity |
Pieces and/or weight (kg / lb) |
Download ASTM B381 Standard (PDF)
The official ASTM B381 PDF is available from our HT Pipe Download Center. The document covers Titanium and Titanium Alloy Forgings, including full chemical composition tables, mechanical property requirements, dimensional tolerances, and testing provisions.
Go to Download Center | Request MTC / Quotation
12. Frequently Asked Questions
Q: What is the difference between ASTM B381 F-grade and standard Ti grades?
The F-prefix (F-1, F-2, F-5, F-7, etc.) specifically designates forging-grade material verified to meet mechanical properties in the forged condition. While the chemical composition is identical to their wrought counterparts (F-2 = Grade 2 chemistry, F-5 = Grade 5 chemistry), forgings include two critical additions: (1) Reduction of Area (RA) is mandatory — a key ductility metric for forged components (e.g., F-2 requires RA ≥ 30%), and (2) test specimens are extracted from the forging or a forging prolongation, representing actual forged grain flow properties rather than bar properties. This is essential for pressure-containing components where directional mechanical integrity matters.
Q: What are the most commonly ordered ASTM B381 forging grades?
F-2 (Grade 2 CP Ti) is the most common for chemical processing flanges, fittings, and valve bodies — it provides the optimal balance of strength (YS 275 MPa), ductility (El ≥ 20%), and corrosion resistance at the lowest cost. F-5 (Ti-6Al-4V) is the high-strength choice (YS 828 MPa) for aerospace, oil & gas downhole tools, and high-pressure subsea components. F-7 (Ti-Pd) is specified for chemical service where crevice corrosion resistance in chlorides/acids is required (same strength as F-2 but with Pd addition). F-12 (Ti-0.3Mo-0.8Ni) is the choice for moderately elevated temperature service with good corrosion resistance and lower cost than F-7.
Q: Can ASTM B381 titanium forgings be welded?
Yes. Titanium forgings are readily weldable provided oxygen contamination is strictly controlled. F-2 (CP Ti) forgings should be welded with ERTi-2 filler per AWS A5.16. F-5 (Ti-6Al-4V) forgings use ERTi-5 or ERTi-5ELI filler — note that the weld zone in annealed F-5 will have lower strength than the forged base metal due to partial annealing in the HAZ. For critical F-5 welds, post-weld stress relief (480–650°C / 900–1200°F for 2–4 hr) followed by air cool is recommended. F-7 forgings are welded with ERTi-7 filler. All welding requires full inert gas shielding (argon) on both root and cap sides until the weld cools below 320°C (600°F) to prevent oxygen embrittlement.
Q: What NDE is required for ASTM B381 forgings?
Standard ASTM B381 does not mandate NDE (nondestructive examination) — it is specified by the purchaser per application requirements. For pressure-containing components (ASME BPVC), ultrasonic examination per ASTM B594 or equivalent is standard practice. For aerospace forgings, UT per AMS 2631 and penetrant testing per ASTM E165 are commonly specified. For subsea and critical chemical service, 100% UT of the finished forging is recommended to detect any internal laps, bursts, or hydrogen-induced discontinuities. Surface condition: the forging supplier typically provides a descaled and grit-blasted finish; the purchaser specifies final machined condition, NDE, and acceptance criteria.
Q: What are the size limitations for ASTM B381 titanium forgings?
Titanium forgings are limited by press capacity rather than the specification. Closed-die (impression die) forgings: up to approximately 5000 kg (11,000 lb) from a 50,000-ton hydraulic press; typical Ti closed-die forging weights are 5–500 kg for flanges and fittings. Open-die (free forging): up to approximately 20,000 kg (44,000 lb) for turbine discs and large pressure vessel forgings. Ring-rolled forgings: up to 4 m (13 ft) diameter for large-diameter flanges and pressure vessel shell courses. The upper size limit is also governed by the available billet diameter — Ti billets are typically available up to 900 mm (36 in) diameter for standard grades (F-2, F-5).
Request a Quote — ASTM B381 Titanium Forgings (F-1, F-2, F-5, F-7, F-12 — All Grades)
Zhengzhou Huitong (HT Pipe) supplies ASTM B381 / SB381 titanium forgings in all standard grades — F-2 (CP Ti), F-5 (Ti-6Al-4V), F-7 (Ti-Pd), and F-12 (Ti-0.3Mo-0.8Ni) for flanges, fittings, and custom shapes. Full EN 10204 3.1 CMTRs with tensile, chemistry, and RA certification. NDE per ASTM B594 when specified.
