Super Duplex Stainless Steel Ferralium 255 Round Bar
➡️ Alloy 255 | SD50 | UNS S32550 | EN/DIN 1.4507
➡️ ASTM, EN, JIS & International Standards
➡️ Supply Conditions
➡️ Multiple Diameters & Supply Lengths
➡️ Global Export & International Delivery
Country of Origin:
Europe, Japan, USA
Material Type:
Super Duplex Stainless Steel
UNS Number:
S32550
Wr. No.:
1.4507
MTC Available:
EN 10204 3.1
Product Description for Super Duplex Stainless Steel Ferralium 255 Round Bar
Ferralium 255 is a copper-bearing super duplex (austenitic-ferritic) stainless steel round bar covered by UNS S32550 and EN 1.4507 (X2CrNiMoCuN25-6-3). Ferralium is a registered trademark of Langley Alloys Limited (UK); the same UNS/EN grade is also produced and supplied by other mills and distributors under generic designations such as “Alloy 255.” Ferralium 255 was originally developed in the 1960s and is recognized as one of the earliest super duplex grades, notable for pioneering the deliberate addition of nitrogen as a strengthening and corrosion-resistance element in duplex stainless steel.
The alloy’s defining metallurgical feature relative to other 25Cr super duplex grades (such as 2507 or Zeron 100) is a significant copper addition (nominally 1.5–2.5%), which gives it improved resistance to reducing acids particularly sulfuric, phosphoric and nitric acid while still providing a Pitting Resistance Equivalent (PREN) that is typically above 40, though it can fall closer to 38 depending on heat chemistry, so certification should be checked against the specific application’s minimum PREN requirement.
Ferralium 255 round bar is supplied in the hot worked and solution-annealed condition, most commonly to ASTM A479 (bar for pressure vessels) or ASTM A276 (bars and shapes, Condition A), with EN 10088-3 as the corresponding European bar standard, and ASTM A182 Grade F61 covering the equivalent forged product form. It is listed under NACE MR0175 / ISO 15156 for sour service and has gained ASME approval for pressure vessel applications.
Typical uses include phosphoric and sulfuric acid production equipment, seawater and brine-handling components, pump and valve parts, and other chemical processing applications where resistance to reducing acids is a priority alongside chloride pitting resistance. Purchasers should confirm the governing product standard, required PREN/heat chemistry, delivery condition, and any NACE hardness limits before ordering.
Common Applications of Super Duplex Stainless Steel Ferralium 255 Round Bar
➡️ Machined shafts, spindles, valve stems, pump sleeves and pins for food, beverage, dairy and pharmaceutical equipment, where the passive chromium oxide film resists both product acids and caustic clean-in-place chemicals.
➡️ Fasteners, studs, bolts, threaded rod and anchor components produced from bar stock, chosen for corrosion resistance combined with the ductility needed for cold heading and thread rolling.
➡️ Chemical, water treatment and general process plant parts such as agitator shafts, flange blanks, nozzles and support components handling water, steam and mildly corrosive media free of significant chlorides.
➡️ Architectural and structural hardware including handrail stanchions, balustrade fittings, tension rods and bollards, where a bright ground or polished bar finish provides both appearance and low maintenance.
International Equivalent Grade for Alloy 255 Round Bar
UNS
USA
UNS S32550
ASTM / AISI / SAE
USA
ASTM A276, A479 / ASTM A182 Grade F61
EN
Europe
1.4507 / X2CrNiMoCuN25-6-3
BS
United Kingdom
BS EN 10088-3 / 1.4507
Technical Specification for Super Duplex Stainless Steel Ferralium 255 Round Bar
Specification
Value
Unit
Material
Copper-bearing super duplex stainless steel
-
Grade
UNS S32550 / EN 1.4507 (Ferralium 255 / Alloy 255)
-
Standard
ASTM A276 / A479; EN 10088-3
-
Product Form
Round bar (hot worked, solution annealed)
-
Diameter
Commercially available up to approximately 400 mm (16 in.) depending on producer; confirm current stock range
mm
Length
Random mill lengths; cut lengths available on request
m
Manufacturing Process
Hot worked (rolled or forged), then solution annealed and water quenched
-
Surface Finish
Hot worked/pickled, peeled, or machined bright
-
Heat Treatment
Solution annealed (typically ~1900°F / ~1040°C) and rapidly cooled
°C
Delivery Condition
Hot worked, annealed, and pickled (Condition A per ASTM A276)
-
Tolerance Standard
ASTM A484 / A480 or EN 10060 / EN 10278
-
Dimensional Tolerance
Per standard; confirm per diameter and finish
mm
Straightness
Per standard / producer specification
mm/m
Carbon Equivalent (CEV)
Not applicable
-
Density
7.81 (0.282)
g/cm³ (lb/in³)
Magnetic Properties
Moderately magnetic (ferromagnetic ferrite phase present in the duplex microstructure)
-
Corrosion Resistance
PREN typically 38–42 (heat-dependent); superior resistance to sulfuric, nitric, and phosphoric acid versus Cu-free super duplex grades, due to the copper addition
-
Thermal Conductivity
13–15 at room temperature
W/(m·K)
Electrical Resistivity / Conductivity
Approx. 0.80
µΩ·m
Specific Heat
~480–500 at room temperature
J/(kg·K)
Coefficient of Thermal Expansion
~13
×10⁻⁶/°C
Melting Range
1385–1443 (2525–2630)
°C (°F)
Technical Specifications
Get the key technical specifications for Super Duplex Stainless Steel Ferralium 255 Round Bar
Ferralium 255 round bar is normally ordered to ASTM A479 when intended for pressure-retaining applications, or ASTM A276 for general bar/shapes use; both reference the same nominal UNS S32550 chemistry but differ in supplementary certification and testing requirements. The alloy is supplied in the hot worked and annealed (and typically pickled) condition annealing dissolves intermetallic phases formed during hot working and restores the corrosion-resistant duplex microstructure, so material must never be placed in service in the as-hot-worked, non-annealed state. Because Ferralium 255’s PREN can range from roughly 38 to 42 depending on the specific heat’s chemistry within the allowed compositional envelope, buyers with a minimum PREN requirement (common in seawater or sour-service specifications) should request heat-specific chemistry confirmation rather than relying on the nominal composition alone. For sour-service (NACE MR0175 / ISO 15156) orders, hardness is typically restricted to a maximum of 28 HRC (approximately 270 HB), which is tighter than the base ASTM A276 hardness ceiling and must be called out explicitly on the purchase order. Surface condition, exact diameter range, and tolerance class vary by producer; Langley Alloys and other Ferralium 255 licensees/producers should be consulted for current stock dimensions and certification options (EN 10204 3.1 vs. 3.2).
Chemical Composition for Super Duplex Stainless Steel Ferralium 255 Round Bar
Element
Symbol
Min
Max
Unit
Carbon
C
-
0.04
%
Chromium
Cr
24.00
27.00
%
Nickel
Ni
4.50
6.50
%
Molybdenum
Mo
2.90
3.90
%
Manganese
Mn
-
1.50
%
Silicon
Si
-
1.00
%
Phosphorus
P
-
0.040
%
Sulfur
S
-
0.030
%
Nitrogen
N
0.10
0.25
%
Copper
Cu
1.50
2.50
%
Iron
Fe
1.50
Balance
%
Chemical Composition
View the chemical composition and applicable material limits for Alloy 255 Round Bar
The defining alloying feature of Ferralium 255 is its copper content of 1.5–2.5%, roughly two to four times that found in tungsten-bearing or plain super duplex grades. Copper does not significantly influence chloride pitting resistance (which is governed primarily by chromium, molybdenum and nitrogen, as captured in the PREN formula) but instead provides a marked improvement in resistance to reducing acids such as sulfuric, phosphoric, and nitric acid a property inherited from earlier copper-bearing austenitic alloys such as Alloy 20, but achieved here with the higher strength of a duplex microstructure.
Nitrogen, though present in a narrower and generally lower range (0.10–0.25%) than in molybdenum-heavy super duplex grades, still contributes meaningfully to both strength and ferrite/austenite phase balance. Molybdenum (2.9–3.9%) and chromium (24–27%) remain the principal chloride-pitting-resistance elements, though at levels that can allow calculated PREN to fall toward the lower end of the “super duplex” range (approximately 38) for some heats, which is why heat-specific verification matters for chloride-critical service.
Carbon is held to a low maximum (0.04%) to limit the risk of sensitizing chromium carbide precipitation during welding or improper heat treatment, and manganese/silicon function mainly as deoxidizers and residual elements rather than deliberate corrosion-resistance contributors.
Mechanical Properties for Super Duplex Stainless Steel Ferralium 255 Round Bar
Mechanical Property
Value
Unit
Tensile Strength
750
MPa
Yield Strength / 0.2% Proof Strength
550
MPa
Elongation
25
%
Reduction of Area
25
%
Hardness
270 - 290
HBW
Proof Stress / 0.2% Proof Strength
720
MPa
Ultimate Tensile Strength
860
MPa
Mechanical Properties
Check the key mechanical properties and performance requirements of Alloy 255 Round Bar
Ferralium 255’s 550 MPa minimum yield strength in the standard annealed condition provides roughly twice the load-bearing capacity per unit cross-section of annealed 316L stainless bar, supporting the use of lighter, smaller-section components in pumps, valves and structural parts exposed to corrosive service. The 25% minimum elongation and generally good ductility reflect a well-balanced austenite-ferrite microstructure, though as with all duplex grades toughness and ductility can degrade if the material is exposed to elevated temperatures (above roughly 300°C) for extended periods due to intermetallic phase formation, so service temperature limits should be checked against the application. The maximum hardness limits (290 HBW general service, tightened to 28 HRC for NACE-qualified sour service) exist primarily to control susceptibility to sulfide stress cracking in H₂S environments rather than to limit wear resistance, and hardness should be verified against whichever limit applies to the intended service. For machining, Ferralium 255 work-hardens readily and can be harder to machine than austenitic stainless of similar strength, so slow, steady feeds and rigid tooling are generally recommended, consistent with practice for other super duplex grades.
Dimension / Sizes for Super Duplex Stainless Steel Ferralium 255 Round Bar
Dimension / Size
Value
Unit
Diameter
upto approximately 400 mm
mm
Standard Length
Random mill lengths; typically several meters
m
Custom Length
Cut-to-length available on request
mm
Diameter Tolerance
Per standard; confirm with supplier
mm
Length Tolerance
Per standard / customer specification
mm
Straightness Tolerance
Per standard / producer specification
mm/m
End Condition
As-cut (saw cut); chamfered on request
-
Surface Finish
Hot worked and pickled, peeled, or machined bright
-
Out-of-Roundness
Per dimensional standard
mm
Ovality
Per dimensional standard
mm
Dimensions & Sizes
Explore available diameters, lengths, and dimensional requirements for Alloy 255 Round Bar
Pricing for Super Duplex Stainless Steel Ferralium 255 Round Bar
Round Bar Prices are generally quoted per kilograms or meters tonnes and can fluctuate with the global raw material and market prices. The final price will depend on a variety of factors, including the grade size, diameter, length, surface finish, the quantity and whether the bars are cut to length or in standard lengths.
For smaller quantities, we can also quote per metre or per piece basis once the required dimensions have been confirmed. Container-loads or orders that are larger in size are typically priced per tonne, based upon the specifications required and the supply conditions.
Please provide your desired dimensions, grades, length number, and end for a current quote including the lead time applicable and details for certification.
Pricing
Get current Super Duplex Stainless Steel Ferralium 255 Round Bar pricing based on size, quantity, grade, finish, and delivery requirements.
Why Choose Us
Euro Steel Bars is an international distributor, stockist and exporter of stainless round steel bars that cover carbon, stainless alloy, special grades. We stock a variety of sizes and grades. We guarantee every order with mill test certificates as well as full quality-assurance documentation. Our name speaks to our roots: European-sourced materials that is backed by the certificates and rigor that buyers from Asia as well as the Gulf and Africa are looking for.
Each bar we deliver is accompanied by EN 10204 3.1 mill test certificates as well as complete documentation of quality, so what you receive corresponds to what’s written in the documents. We carry a selection of sizes and grades ready for transport, and cut length upon the request of customers, which results in quicker lead times, whether you’re ordering just a one-off spec or a complete project tonnage.
We operate an actual wholesale business that is that is supported with an internationally-operated supply chain therefore we are able to serve fabricators sourcing one grade the same way in the same way as an EPC contractor who is placing a large order. Our clients include manufacturers, fabricators EPC construction companies, engineers oil and gas projects as well as construction companies. we design our inventory as well as documentation to show what buyers need to bring projects forward.
Our customers trust us across Qatar, Oman, Bahrain, Kuwait, Jordan, Malaysia, Singapore, Thailand, Taiwan, Turkey, Italy and South Africa. If you’re looking to source an Gulf energy project, or a construction project within Southeast Asia, you get the same quality of certified material, the exact documentation, and the exact delivery procedure.
Frequently Asked Questions
What is Ferralium 255?
What standard does Ferralium 255 round bar comply with?
What are Ferralium 255's international equivalent grades?
What heat treatment condition is Ferralium 255 round bar supplied in?
Is Ferralium 255 suitable for welding?
What is Ferralium 255's corrosion resistance?
Where is Ferralium 255 round bar commonly used?
Can custom sizes or lengths be supplied?
Request A Quote
Need a specific grade, size or quantity? Get pricing and availability for your requirement.