ASTM A276/A276M is the ASTM International specification for stainless steel bars and shapes intended for general engineering applications where corrosion resistance is required. It covers hot-rolled, hot-rolled and descaled, and cold-finished bars in austenitic, ferritic, martensitic, and precipitation-hardening grades. HT PIPE stocks and supplies A276 bars in all standard grades with Mill Test Certificates per EN 10204 3.1.

1. Standard Scope & Designation

ASTM A276 covers stainless steel bars and shapes in the following product forms and finishes:

2. Stainless Steel Grades Covered

2.1 Austenitic Grades

2.2 Ferritic & Martensitic Grades

2.3 Precipitation-Hardening Grades

Note: A276 does not include duplex or super-duplex grades. Duplex bars (2205, 2507) for pressure vessels use ASTM A479.

3. Chemical Composition — Key Grades (ASTM A276 Table 1)

Values are maximum unless shown as a range. Product analysis tolerances per ASTM A480/A480M.

Note: Precipitation-hardening grades (630/17-4PH, 631/17-7PH) have complex compositions including Cu, Al, Ti. Full tables in ASTM A276-17. Free-machining grades 303/416/430F have elevated S (0.15–0.35%) for improved machinability.

4. Mechanical Property Requirements (ASTM A276 Table 2)

Note: For cold-drawn bars, tensile and yield strengths are typically higher than annealed values. Precipitation-hardening grades (17-4PH, 17-7PH) achieve much higher strengths after aging heat treatment. Values shown are for hot-finished or annealed condition.

5. Heat Treatment Requirements

6. Testing & Inspection Requirements

7. Dimensions & Tolerances

Hot-rolled round bar: ±0.5 mm for 25–50 mm dia.; ±1.0 mm for 50–100 mm dia. Cold-drawn: h9–h11 tolerances (much tighter). Full tables in ASTM A484/A484M.

8. Industries & Applications

9. ASTM A276 vs ASTM A479 — Key Differences

10. Related Standards

11. How to Order — Required Information

12. Frequently Asked Questions

Q: What is ASTM A276 used for?

ASTM A276 covers stainless steel bars for general engineering: machined components (shafts, fittings, adapters), fasteners (bolts, screws), springs (302, 17-7PH), medical instruments (304L, 316L, 420, 440C), and structural parts in the food, pharmaceutical, chemical, and marine industries.

Q: What is the difference between ASTM A276 and A479?

A276 is a general-purpose bar specification for machined parts and mechanical components. A479 is written specifically for boilers and pressure vessels with mandatory end hardness testing on every bar, mandatory documented solution annealing, and ASME BPVC adoption (SA-479). A276 is more economical for non-Code applications.

Q: Can ASTM A276 303 bar be used for pressure vessels?

No. Type 303 (free-machining, S 0.15% min) is specifically excluded from ASTM A479 (pressure vessel bars) and ASME SA-479. For pressure vessel use, use Type 304 or 316 bars to A479/SA-479 with proper annealing and traceability documentation.

Q: What is 17-4PH stainless steel bar used for?

17-4PH (ASTM A564 Type 630, also covered by A276) is a precipitation-hardening stainless steel achieving tensile strengths up to 1310 MPa (190 ksi) after aging. Used in aerospace landing gear, nuclear reactor components, valve stems, pump shafts, and high-strength corrosion-resistant mechanical parts.

Q: What surface finish should I specify for machining?

Cold-drawn (CD) bars offer the best combination of machinability and cost: bright smooth surface, tight tolerances (h9–h11), and minimal material allowance. For high-precision or final-dimension parts, specify turned and polished (T&P) or ground bars. Hot-rolled bars (black oxide) are most economical but require more machining allowance.

Q: What are the mechanical properties of ASTM A276 Type 316L?

ASTM A276 Type 316L (UNS S31603): minimum tensile strength 485 MPa (70 ksi), minimum yield strength 0.2% offset 170 MPa (25 ksi), elongation min. 40% in 2 in., hardness max. 217 HB / 95 HRB, in the annealed condition. Note: cold-drawn 316L bars typically achieve ~620 MPa tensile / ~310 MPa yield in the as-drawn condition.