Duplex Round Bar Supplier
MTS supplies duplex round bar in 2205 and super duplex 2507, and 904L for acid service. Bar comes cold drawn, ground or forged black, from small diameters up to Φ300 mm.
UNS S31803 / S32205 and S32750 to ASTM A276 and A479
Solution annealed; cold drawn to h9–h11 or ground to h7/h8
Ferrite, ASTM A923 and impact tests on request
Part of our 4,500 tons of stainless bar stock (out of 80,000 tons in total) in Wuxi
Why Order Duplex Steel Round Bar From Us
01
Tests for the Problems Duplex Can Hide
Duplex can pass chemistry and tensile tests but still contain harmful phases. On request, we supply bar with ASTM A923 results, so those phases are ruled out before shipping.
02
Ferrite Balance on Request
Ferrite content, usually 35–55%, can be reported per heat when your specification calls for it.
03
Full Size Range in One Grade
Cold drawn and ground bar for fasteners and valve stems, forged bar up to Φ300 mm for shafts and flanges. You do not need a second source for large sizes.
04
Paperwork for Oil, Gas and Marine Projects
EN 10204 3.1 certificates as standard. Third-party inspection by BV, DNV, SGS or your inspector on request.
Twice the Strength of 316L, With Better Chloride Resistance
Duplex steel has a mixed structure, about half austenite and half ferrite. That gives it roughly twice the yield strength of 316L. It also resists pitting and stress corrosion cracking far better.
For shafts, bolts and valve stems, this means a smaller diameter or a longer life. For parts in seawater or brine, it means fewer replacements. In many designs, 2205 costs less over the part’s life than 316L.
Duplex and Super Duplex Round Bar Grades
2205 Duplex Round Bar
UNS S31803 / S32205, EN 1.4462. The standard duplex grade for pumps, valves, shafts and fasteners in chloride service.
Super Duplex Round Bar 2507
UNS S32750, EN 1.4410. Higher chromium, molybdenum and nitrogen for seawater and offshore parts.
Super Duplex S32760
EN 1.4501, with added copper and tungsten. Often specified for firewater, seawater and subsea systems. Supplied by mill order.
Lean Duplex Rod
UNS S32101 (LDX 2101), EN 1.4162. Lower cost duplex rod for structural and storage uses where 304 or 316 are not strong enough. Supplied by mill order.
904L Round Bar
Not a duplex grade, but often compared. 904L stainless steel round bar is austenitic, with high nickel and copper. It suits sulfuric acid and warm seawater.
Specifications
| Item | Range |
|---|---|
| Grades | 2205 (S31803 / S32205), 2507 (S32750), 904L (N08904); S32760 and S32101 by mill order |
| Cold drawn bright bar | Up to Φ100 mm; h9–h11 |
| Ground bar | h7/h8; Ra 0.2–0.8 µm |
| Forged black bar | Φ200–300 mm; peeled on request |
| Length | 2 m, 3 m, 6 m; 9 m and 12 m on request |
| Condition | Solution annealed and water quenched |
| Standards | ASTM A276, ASTM A479, EN 10088-3 |
| Testing on request | Ferrite (ASTM E562), ASTM A923, Charpy impact, UT |
How to Specify Duplex Round Bar
Duplex bar is a step up from 316L in strength and chloride resistance. It is also less forgiving. The same chemistry can give good or poor bar, depending on how it was annealed and cooled. Here is what to check.
2205, Super Duplex or Lean Duplex?
2205 is the workhorse. It handles seawater spray, brackish water and most process chlorides. It is the default for pump shafts, valve stems and fasteners.
Super duplex (2507 or S32760) adds more chromium, molybdenum and nitrogen. Its PREN is above 40. Use it for full seawater immersion, warm brine and subsea parts.
Lean duplex (2101) has less nickel and molybdenum. Its corrosion resistance is close to 304 or 316, but with double the strength. It suits structural and tank uses, not seawater.
Our view: do not jump to super duplex by default. If 2205 handles your temperature and chloride level, it is easier to buy and machine.
Why Duplex Needs Extra Tests
Duplex depends on a balance of ferrite and austenite. Too much ferrite lowers toughness. Slow cooling can form sigma and other intermetallic phases. These make the steel brittle and weaken its corrosion resistance.
Standard chemistry and tensile tests do not catch this. For critical parts, specify:
- Ferrite count to ASTM E562, usually 35–55%
- ASTM A923 Method A, B or C, to detect harmful phases
- Charpy impact at a low temperature, often −46°C, for offshore parts
Large diameters cool slowly, so they carry more risk. For bar above about 150 mm, include these tests in your order.
Duplex Versus 904L
Both are upgrades from 316L. They solve different problems.
Duplex gives high strength and good chloride resistance at moderate cost. 904L has lower strength but excellent resistance to sulfuric and phosphoric acid. It also stays non-magnetic.
Choose duplex for loaded parts in seawater and chlorides. Choose 904l round bar for acid plants and parts that must not be magnetic. For a full comparison with the 316 family, see SS 316 Rod.
Temperature Limits
Duplex grades should not run long-term above about 250–300°C. Above that, they can become brittle. Below about −50°C, toughness also drops.
If your part runs hotter, an austenitic grade is safer. If it runs colder, check impact values at your design temperature.
Machining Duplex Rod
Duplex is harder to machine than 316L because of its strength. Expect lower cutting speeds and more tool wear. Use rigid setups and sharp carbide tools.
Plan for this in your part cost. The bar price is only part of the difference.
Frequently Asked Questions
What is the difference between S31803 and S32205?
Both are 2205 duplex. S32205 has tighter, higher limits on chromium, molybdenum and nitrogen. That gives slightly better corrosion resistance. Much of today’s 2205 bar is dual certified to both numbers.
Is duplex round bar magnetic?
Yes. Its ferrite phase makes duplex magnetic, though less than carbon steel. If your part must be non-magnetic, choose an austenitic grade such as 316L or 904L.
Can duplex replace 316L in my design?
Often, yes. Duplex 2205 is stronger and resists chlorides better. You may be able to use a smaller diameter. Check welding procedures, operating temperature and magnetism first.
Do you supply super duplex bar for offshore projects?
Yes. We supply 2507 round bar, with ferrite, A923 and impact tests on request. Send your project specification, and we will confirm which requirements the bar can meet before quoting.
How is duplex rod packed for export?
Bars are bundled, capped at both ends and wrapped against moisture. Each bundle is tagged with grade and size. Duplex is kept apart from carbon steel to avoid iron contamination.
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