Open-die forged round and rectangular bar to ASTM A182 F61 / EN 10222-5 for heavy-section components
When the cross-section exceeds the practical limit of hot-rolling (typically 200 mm round bar) or the application demands the directional grain flow of a wrought structure, forged bar takes over. Heavy valve bonnets, downhole tool bodies, subsea wellhead spool stock, and large-diameter flange forgings begin life as forged bar billets. Open-die forging works the cast ingot to a 4:1 reduction ratio at minimum (NORSOK M-650 default for super duplex), breaks up the as-cast dendritic structure, and delivers the wrought ferrite-austenite microstructure required for sour-service qualification. Ferralium 255 (UNS S32550, EN 1.4507) forged bar to ASTM A182 grade F61 covers diameters from 60 mm up to 600 mm round and 100 × 100 mm to 500 × 500 mm rectangular sections. Per-heat EN 10204 type 3.2 MTC with full mechanical, hardness, ferrite, Charpy, and NACE MR0175 conformance. RFQ: info@torqbolt.com / WhatsApp +91-22-66157017.
| Form | Section size | Length | Process |
|---|---|---|---|
| Round forged bar | 60 mm to 600 mm dia | up to 4 m | Open-die round-pass forging |
| Square / rectangular forged | 100 to 500 mm side | up to 4 m | Open-die flat-die forging |
| Stepped or contoured forging | per drawing | per drawing | Open-die incremental reduction |
| Hollow forged shell (mandrel-forged) | OD 200 to 600 mm, wall 25 to 100 mm | up to 3 m | Mandrel forging on a horizontal press |
NORSOK M-650 specifies a minimum 4:1 forging reduction ratio for super duplex grades to break the cast structure and develop a wrought microstructure. The reduction ratio is the original ingot cross-section area divided by the final forged section area. A 600 mm ingot worked to a 300 mm forged round bar achieves a 4:1 ratio (since the area ratio is the square of the diameter ratio). Forging is performed in the 1050 to 1200 °C austenitisation range, with finish-forge temperature held above 950 °C to avoid sigma-phase precipitation in the inter-pass temperature window (see sigma phase). Final solution-anneal at 1080 °C and water quench restores the 35 to 55% ferrite content per ASTM E562.
