Surface Treatments
Certifications
- ISO 9001:2015
- NORSOK M-650
- NACE MR0175
- ISO 15156-3
- PED 2014/68/EC
- EN 10204 type 3.2
- AD 2000 W2/W7/W10
ASTM A479 Ferralium 255 Bar (UNS S32550), Specification & Compliance
ASTM A479 / A479M, "Standard Specification for Stainless Steel Bars and Shapes for Use in Boilers and Other Pressure Vessels", is the primary specification for Ferralium 255 (UNS S32550) bar and billet supplied for pressure-boundary service. The spec covers chemistry, mechanical properties, heat treatment, marking, dimensional tolerance, and the inspection / test report requirements that the bar must meet to be classified as A479 grade S32550.
Scope
ASTM A479 covers hot-finished and cold-finished bar (rounds, hexagons, squares, flats), forged bar, and shapes in the chemical compositions listed in Table 1 of the spec. UNS S32550 (Ferralium 255) is included in the ferritic / austenitic (duplex) section. The spec applies to bar intended for boilers, pressure vessels, heat exchangers, and high-pressure piping components.
Chemistry per ASTM A479 (UNS S32550)
| Element | Min % | Max % |
|---|---|---|
| Carbon (C) | none | 0.04 |
| Manganese (Mn) | none | 1.50 |
| Phosphorus (P) | none | 0.04 |
| Sulphur (S) | none | 0.030 |
| Silicon (Si) | none | 1.00 |
| Chromium (Cr) | 24.0 | 27.0 |
| Nickel (Ni) | 4.50 | 6.50 |
| Molybdenum (Mo) | 2.90 | 3.90 |
| Copper (Cu) | 1.50 | 2.50 |
| Nitrogen (N) | 0.10 | 0.25 |
Mechanical Property Requirements
| Property | Minimum (UNS S32550) |
|---|---|
| Yield strength, 0.2% offset (Rp0.2) | 550 MPa (80 ksi) |
| Ultimate tensile strength (Rm) | 760 MPa (110 ksi) |
| Elongation in 50 mm (A5) | 15% |
| Hardness, max (Brinell) | 302 HBW |
| Hardness, max (Rockwell C) | 32 HRC |
Heat Treatment Requirement
Per ASTM A479: bar shall be solution-annealed at 1040 °C minimum (1900 °F) followed by water quench or rapid cooling to prevent precipitation of intermetallic phases. TorqBolt practice for Ferralium 255 is 1100 °C solution anneal + water quench, which gives more conservative ferrite-balance margin (45–50% ferrite typical) and lower risk of sigma-phase.
Inspection & Testing per A479
- Chemical analysis (heat analysis + product analysis verification)
- Tensile test per ASTM A370 / E8
- Hardness test (Brinell HBW or Rockwell HRC)
- Intergranular corrosion test per ASTM A923 method A or C (when specified)
- Ferrite content per ASTM E562 or ASTM A923 (when specified)
- Mill Test Certificate per EN 10204 type 3.1 or 3.2
TorqBolt Compliance & Documentation
TorqBolt supplies Ferralium 255 (UNS S32550) bar to ASTM A479 with per-heat EN 10204 type 3.2 MTC documenting full chemistry, mechanical properties, heat-treatment certificate, ferrite content per ASTM E562, and PREN calculation. Available diameters: 6 mm to 600 mm round bar; hex / square / flat / cold-finished / forged variants. NORSOK M-650 QTR + NACE MR0175 / ISO 15156-3 sour-service compliance documentation available on request. See Ferralium 255 round bar product page.
Need Ferralium 255 bar per ASTM A479? Email info@torqbolt.com or WhatsApp +91-22-66157017 with form, dimensions, quantity, ASTM/EN spec, MTC level (3.1 / 3.2). NACE MR0175 sour-service stamp on every heat. NORSOK M-650 QTR on request. Per-heat EN 10204 type 3.2 MTC included with every consignment.
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