ASTM A479/A479M is the ASTM International specification for stainless steel bars and shapes intended for use in boilers and other pressure vessels, and for general applications requiring corrosion resistance. The companion ASME SA-479 adopts identical requirements for ASME BPVC compliance. HT PIPE stocks A479 bars in all major grades with full traceability and Mill Test Certificates per EN 10204 3.1.
1. Standard Scope & Designation
ASTM A479 covers hot-rolled or cold-finished stainless steel bars and shapes in straight lengths:
| Form |
Typical Sizes |
Finish |
| Round Bar |
6–330 mm diameter |
Hot-rolled, T&P, cold-drawn |
| Square Bar |
6–200 mm |
Hot-rolled, cold-finished |
| Hexagon Bar |
8–100 mm AF |
Cold-drawn, cold-finished |
| Flat Bar |
Width 10–200 mm; t 3–50 mm |
Hot-rolled, cold-rolled |
Scope Statement (ASTM A479-23): "This specification covers stainless steel bars and shapes for use in boilers and other pressure vessels and for general application purposes."
| Designation |
Issuing Body |
Unit System |
Latest Edition |
| ASTM A479 |
ASTM International |
Inch-Pound |
A479-23 |
| ASTM A479M |
ASTM International |
SI (Metric) |
A479M-23 |
| ASME SA-479 |
ASME (BPVC Sec. II Part A) |
Both |
2023 Edition |
2. Stainless Steel Grades Covered
2.1 Austenitic Grades
| Grade |
UNS No. |
Key Feature |
Typical Applications |
| 304 / 304L |
S30400 / S30403 |
18Cr-8Ni / Low C |
Pressure vessels, tanks, piping |
| 316 / 316L |
S31600 / S31603 |
16Cr-10Ni-2Mo |
Marine, chemical, pharma |
| 321 / 321H |
S32100 / S32109 |
Ti-stabilized; high-temp |
Exhaust, turbine, aerospace |
| 347 / 347H |
S34700 / S34709 |
Nb-stabilized; high-temp |
Pressure vessels, high-temp piping |
| 310S / 309S |
S31008 / S30908 |
25Cr-20Ni / 22Cr-12Ni heat resisting |
Furnace parts, heat exchangers |
2.2 Ferritic & Martensitic Grades
| Grade |
UNS No. |
Type |
Typical Applications |
| 410 |
S41000 |
Martensitic |
Turbine blades, valve parts, shafts |
| 416 / 416Se |
S41600 / S41623 |
Martensitic (free-machining) |
Automatic screw machine parts |
| 420 |
S42000 |
Martensitic |
Surgical instruments, cutlery |
| 440A / 440C |
S44002 / S44004 |
Martensitic (high-C) |
Bearings, valves, surgical tools |
| 430 / 430F |
S43000 / S43020 |
Ferritic / Ferritic (free-mach.) |
Decorative, nitric acid service |
2.3 Duplex Grades
| Grade |
UNS No. |
PREN |
Typical Applications |
| 2205 |
S31803 / S32205 |
~35 |
Oil & gas, chemical process |
| F53 / F55 |
S32750 / S32760 |
40–43 |
Offshore, seawater, subsea |
Full grade listing per ASTM A479-23 Tables 1–6. Free-machining grades 303 (S30300), 416 (S41600), 430F (S43020), 440F (S44020) are also listed.
3. Chemical Composition — Key Grades (ASTM A479 Table 1)
Values are maximum unless shown as a range. Product analysis tolerances per ASTM A480/A480M.
| Grade |
C % |
Mn % |
Si % |
P % |
S % |
Cr % |
Ni % |
Mo % |
N % |
Other |
| 304 |
0.07 |
2.00 |
0.75 |
0.045 |
0.030 |
17.5–19.0 |
8.0–10.5 |
— |
0.10 |
— |
| 304L |
0.030 |
2.00 |
0.75 |
0.045 |
0.030 |
17.5–19.0 |
8.0–12.0 |
— |
0.10 |
— |
| 316 |
0.07 |
2.00 |
0.75 |
0.045 |
0.030 |
16.0–18.0 |
10.0–14.0 |
2.0–3.0 |
0.10 |
— |
| 316L |
0.030 |
2.00 |
0.75 |
0.045 |
0.030 |
16.0–18.0 |
10.0–14.0 |
2.0–3.0 |
0.10 |
— |
| 321 |
0.08 |
2.00 |
0.75 |
0.045 |
0.030 |
17.0–19.0 |
9.0–12.0 |
— |
0.10 |
Ti: 5×C–0.70 |
| 347 |
0.08 |
2.00 |
0.75 |
0.045 |
0.030 |
17.0–19.0 |
9.0–13.0 |
— |
— |
Nb+Ta: 10×C–1.00 |
| 410 |
0.15 |
1.00 |
1.00 |
0.040 |
0.030 |
11.5–13.5 |
0.75 |
— |
— |
— |
| 430 |
0.12 |
1.00 |
1.00 |
0.040 |
0.030 |
16.0–18.0 |
0.75 |
— |
— |
— |
| 2205 |
0.030 |
2.00 |
1.00 |
0.030 |
0.020 |
22.0–23.0 |
4.5–6.5 |
3.0–3.5 |
0.14–0.20 |
— |
Note: Free-machining grades (303, 416, 430F) have S up to 0.15–0.35%. Martensitic 440A/440C have C up to 0.60–1.20%. Full tables in ASTM A479-23.
4. Mechanical Property Requirements (ASTM A479 Table 2)
Minimum requirements in the required heat-treated condition. Elongation gauge: 4D for round bar specimens.
| Grade |
UNS |
Tensile Strength min
MPa (ksi) |
Yield Strength 0.2%
min MPa (ksi) |
Elongation
min % |
Hardness max |
| 304 |
S30400 |
515 (75) |
205 (30) |
30 |
201 HB / 92 HRB |
| 304L |
S30403 |
485 (70) |
170 (25) |
30 |
201 HB / 92 HRB |
| 316 |
S31600 |
515 (75) |
205 (30) |
30 |
217 HB / 95 HRB |
| 316L |
S31603 |
485 (70) |
170 (25) |
30 |
217 HB / 95 HRB |
| 321 |
S32100 |
515 (75) |
205 (30) |
30 |
217 HB / 95 HRB |
| 347 |
S34700 |
515 (75) |
205 (30) |
30 |
217 HB / 95 HRB |
| 310S |
S31008 |
515 (75) |
205 (30) |
30 |
217 HB / 95 HRB |
| 410 |
S41000 |
450 (65) |
205 (30) |
20 |
217 HB / 96 HRB |
| 430 |
S43000 |
450 (65) |
205 (30) |
22 |
183 HB / 89 HRB |
| 2205 |
S32205 |
620 (90) |
450 (65) |
25 |
293 HB / 31 HRC |
Martensitic grades in hardened & tempered condition have different requirements. Hardness for martensitic 410: max 217 HB in annealed condition; up to 40 HRC in hardened & tempered condition.
5. Heat Treatment Requirements
| Grade Family |
Required Condition |
Heat Treatment |
Cooling |
| Austenitic (304, 316, 321, 347…) |
Solution Annealed |
1010–1120°C (1850–2050°F) |
Rapid quench — water or air |
| Ferritic (430…) |
Annealed |
760–900°C (1400–1650°F) |
Air cool or water quench |
| Martensitic (410, 420…) |
Annealed or H&T |
Anneal: 750–900°C; Harden: 925–1010°C; Temper: per type |
Air/oil quench; subsequent temper |
| Duplex (2205…) |
Solution Annealed |
1020–1100°C (1870–2010°F) |
Rapid water quench |
6. Testing & Inspection Requirements
| Test |
Requirement |
Reference |
| Chemical Analysis (Heat) |
One per heat; all elements per grade table |
ASTM A479 Tables 1–6 |
| Tensile Test |
One per lot; longitudinal bar specimen (4D gauge) |
ASTM A370 |
| Hardness Test |
Mandatory on each end of each bar |
ASTM E10 / E18 |
| Intergranular Corrosion |
Supplementary — "L" grades and stabilized grades |
ASTM A262 Practice A or E |
| Intermetallic Phase (Duplex) |
Supplementary — duplex grades |
ASTM A923 Method A, B, or C |
7. Dimensions & Tolerances
| Product |
Size Range |
Tolerance Standard |
Typical Length |
| Hot-Rolled Round Bar |
13–330 mm dia. |
ASTM A484/A484M |
3–6 m random |
| Cold-Finished Round Bar |
6–100 mm dia. |
ASTM A484/A484M (CF) |
3–6 m / exact length |
| Square & Hexagon Bar |
6–200 mm |
ASTM A484/A484M |
3–6 m random |
| Flat Bar |
Width 10–200 mm; t 3–50 mm |
ASTM A484/A484M |
3–6 m random |
Hot-rolled round bar: ±0.5 mm for 25–50 mm dia.; ±1.0 mm for 50–100 mm dia. Cold-finished bars: h9–h11 tolerances (much tighter). Full tables in ASTM A484/A484M.
8. Industries & Applications
| Industry |
Recommended Grades |
Typical Components |
| Boilers & Pressure Vessels |
304, 304L, 316L, 321, 347 |
Flanges, staybolts, nozzle internals |
| Oil & Gas |
316L, 2205, 410 |
Valve stems, pump shafts, wellhead parts |
| Chemical Processing |
316L, 904L, 2205, 2507 |
Mixer shafts, agitator parts |
| Food & Beverage |
304L, 316L |
Shafts, pump impellers, mixers |
| Fasteners & Hardware |
303, 416, 410, 430F |
Bolts, nuts, screws (free-machining) |
| Medical & Surgical |
420, 440C, 304 |
Surgical instruments, implants |
9. ASTM A479 vs ASTM A276 — Key Differences
| Criteria |
ASTM A479 |
ASTM A276 |
| Primary Application |
Boilers and pressure vessels |
General engineering |
| Heat Treatment |
Solution annealing mandatory; documented |
Annealed, hot-finished, or cold-drawn |
| Hardness Verification |
Mandatory on each end of each bar |
Per lot only |
| Marking |
Heat no., grade, ASTM A479, HT lot |
Heat no., grade, ASTM A276 |
| ASME BPVC |
Adopted as ASME SA-479 (Sec. II Part A) |
Not adopted by ASME |
Selection Tip: For ASME Code-stamped pressure vessels, use ASME SA-479. For general mechanical engineering (shafts, fasteners, hardware), ASTM A276 is more economical. Always consult the governing code for your specific application.
10. Related Standards
| Standard |
Scope |
Relationship |
| ASTM A276 |
Stainless Steel Bars and Shapes (general) |
General-purpose alternative to A479 |
| ASTM A484/A484M |
General Requirements for Stainless Steel Bars |
Dimensional & tolerance standard |
| ASTM A370 |
Mechanical Testing of Steel Products |
Tensile, hardness test methods |
| ASTM A262 |
Sensitization / IGC Testing |
Supplementary requirement for A479 |
| ASME SA-479 |
ASME BPVC Section II Part A |
ASME adoption for Code work |
11. How to Order — Required Information
| No. |
Item |
Requirement / Example |
| 1 |
Specification |
ASTM A479 or ASME SA-479 |
| 2 |
Grade / Type |
e.g., Type 304 (UNS S30400) |
| 3 |
Product Form |
Round, square, hexagon, flat bar |
| 4 |
Size / Dimensions |
e.g., Round 50 mm dia. × 3 m |
| 5 |
Finish / Condition |
Hot-rolled; T&P; cold-drawn; solution annealed |
| 6 |
Supplementary Tests |
A262 IGC, A923 intermetallic, UT |
| 7 |
Certification |
EN 10204 3.1 CMTR |
| 8 |
Quantity |
Weight (kg / metric ton) |
12. Frequently Asked Questions
Q: What is ASTM A479 stainless steel bar used for?
ASTM A479 bars are used inside boilers and pressure vessels (staybolts, flange ring segments, nozzle internals, baffles), for general corrosion-resistant mechanical applications (shafts, pump parts, valve stems), and for machined components in the food, pharmaceutical, chemical, oil & gas, and medical industries.
Q: What is the difference between ASTM A479 and ASTM A276?
ASTM A479 is written for pressure vessel bars with mandatory end hardness testing on each bar, mandatory documented solution annealing, and mandatory lot traceability. ASTM A276 is a general-purpose bar specification without these requirements. A479 is adopted by ASME as SA-479; A276 is not part of ASME BPVC.
Q: What are the mechanical properties of ASTM A479 Type 316L?
Type 316L (UNS S31603): minimum tensile strength 485 MPa (70 ksi), yield strength 0.2% offset min. 170 MPa (25 ksi), elongation min. 30% in 4D gauge length, hardness max. 217 HB / 95 HRB, in solution-annealed condition.
Q: Is ASTM A479 Type 316L bar suitable for marine applications?
Yes — Type 316L provides substantially better chloride corrosion resistance than 304L due to its 2–3% molybdenum addition, making it suitable for marine atmospheres, coastal environments, and light seawater exposure. For highly aggressive seawater or subsea applications, duplex 2205 (PREN ~35) or super-duplex 2507/255 (PREN 40+) are recommended.
Q: What diameter ranges are available for ASTM A479 bars?
Hot-rolled rounds: 13–330 mm diameter. Cold-finished rounds (tighter tolerances, better surface finish): 6–100 mm diameter. Squares: 6–200 mm. Hexagons: 8–100 mm AF (across flats). Length: typically 3–6 m random; exact cut lengths available on request.
Q: Can ASTM A479 bars be used in ASME Code stamped equipment?
Yes — when ordered to ASME SA-479 (the ASME BPVC Section II Part A adoption of ASTM A479). The material must be accompanied by Certified Material Test Reports (CMTR) documenting chemical composition, heat treatment, and mechanical properties, and is subject to authorized inspector review for Code-stamped assemblies.
Request a Quote — ASTM A479 Stainless Steel Bars & Shapes
HT PIPE stocks and supplies ASTM A479 / ASME SA-479 stainless steel bars in all major grades (304, 316, 321, 347, 410, 2205 and more), in rounds, squares, hexagons, and flat bars. EN 10204 3.1 CMTRs included.
