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    Ferralium 255 Round Bar (UNS S32550), ASTM A479

    Ferralium 255 round bar (UNS S32550 / EN 1.4507 / X2CrNiMoCuN25-6-3) is the most-specified product form for super duplex bolting, machined components, and downstream forging stock. Manufactured by TorqBolt at Mumbai & Rajkot, India to ASTM A479 (primary) or ASTM A276 (alternative), supplied solution-annealed at 1100 °C with water quench. Per-heat Mill Test Certificate to EN 10204 type 3.2 with chemistry, mechanical properties, ferrite content per ASTM E562, and PREN calculation.

    Size Range & Tolerances

    Diameter rangeLengthForm / finishTolerance
    6 mm – 50 mmup to 6 mCold-finished / peeled / centreless-groundh9 / h10 (ISO 286)
    50 mm – 200 mmup to 6 mHot-rolled / cold-finishedh11 / k12
    200 mm – 400 mmup to 4 mHot-rolled / forgedk12 / k13
    400 mm – 600 mmcut to lengthForged bar (ASTM A182)k13 / k14

    Chemistry & Properties

    Per ASTM A479 / UNS S32550: Cr 24.0–27.0%, Ni 4.5–6.5%, Mo 2.9–3.9%, Cu 1.5–2.5%, N 0.10–0.25%, balance Fe. Yield ≥ 550 MPa, tensile ≥ 760 MPa, elongation ≥ 15%, hardness ≤ 32 HRC (NACE MR0175 limit), Charpy at −46 °C ≥ 45 J (NORSOK M-630), PREN ≥ 40, CPT ≥ 35 °C per ASTM G48 method A. Full chemistry / mechanical reference on the Ferralium 255 grade page.

    Typical End-Use Applications

    • Machined component blanks, Ferralium 255 hex bolts, stud bolts, hex nuts (B16.5 flange bolting)
    • Pump shafts and impellers for seawater service
    • Downhole tool components for oil & gas (NACE MR0175 sour service)
    • Subsea X-mas tree and wellhead internals (NORSOK M-650 qualified)
    • Heat exchanger tube sheets and end caps
    • Forging stock for flanges and fittings (ASTM A182)

    Specification Compliance

    • ASTM A479, primary bar specification
    • ASTM A276, bars and shapes (alternative)
    • EN 10088-3 (1.4507), European long products
    • EN 10272, bar for pressure purposes
    • NORSOK M-650 QTR, manufacturer qualification per MDS D55
    • NACE MR0175 / ISO 15156-3, sour-service compliance per heat
    • EN 10204 type 3.2, per-heat Mill Test Certificate

    Ordering Information

    Specify: diameter (mm or inch); length (mm or m); finish (hot-rolled / cold-finished / peeled / centreless-ground / forged); spec (ASTM A479 / A276 or EN 10088-3); supplementary requirements (NORSOK M-650 QTR, NACE MR0175 compliance, intergranular corrosion test per ASTM A923, ferrite-content range, CPT ≥ 35 °C per ASTM G48). Contact info@torqbolt.com or +91-22-66157017 for quotation and lead time.