Surface Treatments
Certifications
- ISO 9001 - 2015 Certified
- PED 2014/68/EC
- NACE MR0175 / ISO 15156-2
- NORSOK M-650 Qualified
- API 6A Certified
- DFAR
- MERKBLATT AD 2000 W2/W7/W10
Super Duplex 2507 Cold Finished Bar, UNS S32750
Super Duplex 2507 cold finished bar in UNS S32750 (EN 1.4410) is hot-rolled bar that has been further processed by drawing, peeling or centreless grinding to deliver a tighter diameter tolerance and a bright surface. Cold-finished stock is the workhorse for CNC bar-feed turning and for fastener cold-heading where the OD must be held to h9 / h10 / h11 ISO tolerance and the surface must be free of mill scale. TorqBolt holds 2507 cold finished bar from 6 mm through 80 mm at the Mumbai warehouse, with EN 10204 Type 3.1 certificates and Type 3.2 third-party-witnessed on request.
The bar is supplied to ASTM A479 for stainless steel bar in pressure-vessel service and ASTM A484 for general dimensional tolerance. Sour-service certification per NACE MR0175 / ISO 15156-3 is available with controlled hardness and ferrite content.
Super Duplex 2507 Cold Finished Bar Size and Process
| Process | Diameter | Tolerance |
|---|---|---|
| Cold-drawn (CDS) | 6 mm to 50 mm | h9 / h10 / h11 (ISO 286) |
| Peeled and ground (PG) | 20 mm to 80 mm | h9 / h10 |
| Centreless ground (CG) | 6 mm to 60 mm | h9 typical |
| Length | 3.0 to 6.0 m random, cut-to-length on request | |
| Surface roughness | Ra 0.8 to 1.6 micron drawn, Ra 0.4 to 0.8 ground | |
Super Duplex 2507 Cold Finished Bar Chemistry
Per ASTM A479 designation S32750: 25Cr-7Ni-3.5Mo-0.3N. Copper is restricted to 0.50 max as residual, not intentional. PREN of 41 or higher.
| Element | Min % | Max % |
|---|---|---|
| Carbon | (no min) | 0.030 |
| Chromium | 24.0 | 26.0 |
| Nickel | 6.0 | 8.0 |
| Molybdenum | 3.0 | 5.0 |
| Nitrogen | 0.24 | 0.32 |
| Copper | (no min) | 0.50 max, residual, not intentional |
Super Duplex 2507 Cold Finished Bar Mechanical Properties
| Property | Minimum (Annealed) | Test Standard |
|---|---|---|
| Tensile strength | 800 MPa (116 ksi) | ASTM A370 |
| Yield strength | 550 MPa (80 ksi) | ASTM A370 |
| Elongation in 50 mm | 15 percent | ASTM A370 |
| Hardness | 32 HRC max, 28 HRC max NACE | NACE MR0175 |
| Charpy V-notch at minus 46 C | 45 J min | NORSOK M-630 |
Cold Drawing, Peeling and Grinding
Cold-drawn bar (CDS) is pulled through a die after solution annealing to size the OD and produce a bright finish. Peeling removes the as-rolled scale layer with a single-pass turning cut, leaving Ra 0.8 to 1.6 micron. Centreless grinding finishes diameter and roundness to h9 and a Ra 0.4 to 0.8 micron surface, suitable for hydraulic shafts and seal mating surfaces.
- All cold-finished 2507 is solution annealed and water quenched before the cold-finishing step. Cold work after annealing increases hardness and lowers ductility.
- For high-cold-work service (cold-headed fasteners), the final part is re-annealed to recover ferrite balance and toughness.
- Straightness is held to 1 mm per metre on cold-drawn bar; tighter on peeled-and-ground stock.
Super Duplex 2507 Cold Finished Bar Applications
- CNC bar-feed turning of fittings, valve trim and instrument parts
- Cold-heading blanks for stud bolts, hex bolts and cap screws
- Hydraulic cylinder rods and shafts where surface finish drives seal life
- Pump shafts and motor extensions in chloride and sour service
- Rolled-thread fastener stock per ASTM A276 and A479
Related Products and Standards
- Super Duplex 2507 round bar hot-rolled stock
- Super Duplex 2507 hex bar
- Super Duplex 2507 bar overview
- Super Duplex 2507 fasteners
- Super Duplex 2507 stud bolts
- ASTM A479 reference
Super Duplex 2507 Cold Finished Bar FAQ
What is the diameter tolerance on cold-drawn 2507?
h9 (about 0 to minus 0.043 mm at 25 mm) is the standard. h10 and h11 (looser) are available where downstream machining will resize the OD. Tighter tolerances by negotiation, typically with peel-and-grind processing.
Why cold-finish 2507 instead of using hot-rolled bar?
CNC bar feeders need diameter consistency and a bright surface to grip without slip. Hot-rolled bar with mill scale wears feeder collets and creates dimensional variation that ruins automatic part programs. Cold-finished bar drops directly into the bar feeder and runs without re-sizing.
Does cold work change 2507 properties?
Light cold work (drawing for sizing) raises hardness slightly but stays inside the A479 envelope. Heavy cold work (cold-heading for fasteners) work-hardens the surface and must be relieved by solution anneal and water quench to recover the 35 to 55 percent ferrite balance. TorqBolt cold-headed 2507 fasteners are always re-annealed.
Is cold-finished 2507 NACE-compliant?
Yes, after solution anneal the bar meets NACE MR0175 / ISO 15156-3 with 28 HRC max hardness and ferrite within the 35 to 65 percent band. Heavily cold-worked sections must be re-annealed to qualify.
Does 2507 cold finished bar contain copper?
No, copper is not an intentional alloying element in UNS S32750. ASTM A479 permits 0.50 max as residual, not intentional. Copper-bearing super duplex grades (Zeron 100 S32760, Ferralium 255 S32550) are different alloys.
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