Duplex Steel ASTM A276 F51 Round Bar

Duplex Steel ASTM A276 F51 Round Bar Supplier in Mumbai, India

Nicorex Alloys is an ISO 9001 and ISO 14001 certified supplier and stockist based in Mumbai, India. We supply S31803 round bar / F51 round bar with EN 10204 3.1 mill test certificates on every shipment and NACE MR0175/ISO 15156 compliant inventory across popular diameters.

The duplex stainless steel S31803 (UNS S31803 / ASTM A182 F51 / W.Nr. 1.4462) delivers high yield strength, with reliable resistance to corrosion in environments containing chlorides and sour-gas. Its dual-phase microstructure balances approximately 50% austenite and 50% ferrite, combining ferritic strength and austenitic toughness. Mechanical properties per ASTM A276 include a minimum tensile strength of 620 MPa (90 ksi), yield strength of 450 MPa (65 ksi), 25% elongation, and a hardness of 293 HBW or less. PREN typically falls between 31–33, based on the typical S31803 composition.

S31803 is the original 22% Cr duplex designation. S32205 is its tighter-chemistry refinement with guaranteed higher Cr, Mo, and N minimums. Much S31803 produced today also meets S32205, but they are not identical specifications. Diameters range from 6 mm to 350 mm, hot rolled and cold drawn, with an operating range of -50°C to +300°C. Above 300°C, intermetallic precipitation degrades toughness. Specifications include ASTM A276, A479, ASME SA276/SA479, and ASTM A182 F51 for forgings. Industries served include oil and gas, chemical processing, marine, desalination, pulp and paper, and power generation. Also known as Duplex 2205, SAF 2205, and X2CrNiMoN22-5-3.

Duplex UNS S31803 Round Bar Specifications

Duplex S31803 (F51) round bars are in accordance with the following standards, dimensions, parameters, finishes and requirements.

Specification	ASTM A276, A479, ASME SA276, SA479, A182 F51
Forms	Round, Hex, Flat, Square Bar
Diameter	6 mm – 350 mm
Length	1000 – 6000 mm, custom cut
Condition	Solution Annealed (1020–1100°C, water quench)
Finish	Black, Bright, Rough Turned, Centreless Ground

S31803 vs S32205 – Specification Differences for Procurement

S31803 was the original UNS designation for 22% Cr duplex. S32205 is the refined version with tighter chemistry floors. The comparison below highlights procurement-critical differences.

Parameter	S31803 (F51)	S32205 (F60)
Cr range	21.0–23.0%	22.0–23.0%
Mo range	2.5–3.5%	3.0–3.5%
N range	0.08–0.20%	0.14–0.20%
PREN (typical)	~30.5	~35
ASTM Forging	A182 F51	A182 F60
Tensile (min)	620 MPa	655 MPa

S32205 can be dual-certified to S31803, but S31803 cannot automatically qualify as S32205. For critical chloride or sour service, specify S32205 (F60). For general structural applications, S31803 (F51) offers broader mill availability.

Chemical Composition of F51 Round Bar

The S31803 chemical composition per ASTM A276 balances chromium, molybdenum, nickel, and nitrogen for a stable 50/50 austenite-ferrite microstructure.

Element	Chromium (Cr)	Nickel (Ni)	Molybdenum (Mo)	Nitrogen (N)	Carbon (C)	Manganese (Mn)	Silicon (Si)	Phosphorus (P)	Sulphur (S)	Iron (Fe)
Composition	21.0 – 23.0	4.5 – 6.5	2.5 – 3.5	0.08 – 0.20	0.030 max	2.0 max	1.0 max	0.030 max	0.020 max	Balance

S31803 permits a wider nitrogen range (0.08–0.20) compared to S32205 (0.14–0.20). This means S31803 may have lower guaranteed PREN than S32205 on borderline heats.

Mechanical Properties of ASTM A276 S31803 Bar

The mechanical properties of S31803 round bars in a solution-annealed condition, following the standard specification criteria:

Property	Tensile Strength (min)	Yield Strength 0.2% Offset (min)	Elongation in 2 in. (min)	Hardness (max)	Impact Energy (min, -40°C)
Value	620 MPa (90 ksi)	450 MPa (65 ksi)	25%	293 HBW / 31 HRC	45 J (Charpy V-notch)

Yield strength is approximately twice that of 316L (≈205 MPa), enabling thinner cross-sections and material savings in pressure-rated equipment.

Physical Properties of Duplex UNS S31803 Bar

For industrial applications, physical features of S31803 bars have a direct effect on thermal design and calculations for high-precision machining.

Property	Density	Melting Range	Elastic Modulus	Thermal Expansion (20–100°C)	Thermal Conductivity	Electrical Resistivity	Magnetic Permeability
Value	7.8	1350–1400	200	13.0 × 10⁻⁶	15	80	Magnetic (ferrite phase)
Unit	g/cm³	°C	GPa	/°C	W/m·K	µΩ·cm	–

Lower thermal expansion than austenitic grades reduces residual stress in welded fabrications.

Equivalent Grades of F51 Duplex Round Bar

S31803 equivalent designations: A comprehensive guide to global standards, including UNS S32205, EN 1.4462, and Grade F51 specifications.

Property	UNS	Standard Forging	Werkstoff Nr.	EN	AFNOR	ASTM Bar	ASME
Specification	S31803	A182 F51	1.4462	X2CrNiMoN22-5-3	Z2CND22.05Az	A276, A479	SA276, SA479, SA182

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Available Forms of Duplex Steel UNS S31803 Bar

Duplex S31803 bar stock is available in multiple forms for structural, fastener, and rotating-equipment fabrication.

Duplex Steel S31803 Round Bar

ASTM A276 S31803 Hex Bar

Duplex F51 Square Bar

17-4PH Flat Bar

S31803 Forged Bar

Hot Forming, Welding & Machining of Duplex S31803 Bar

Solution anneal at 1020-1100°C (same as hot form) with rapid water quench after all hot work to restore phase balance. Stress relieving is not recommended due to sigma phase risk at 600-900°C. Weld with ER2209 filler (AWS A5.9). No preheating needed. Interpass max 150°C. PWHT is not required for most applications. Machining of this alloy requires rigid setups and lower speeds compared to 316L stainless steel due to its higher yield strength.

Industries of Duplex Steel UNS S31803 Round Bar

Duplex S31803 / F51 bar stock is specified where chloride stress corrosion cracking, high mechanical loads, and sour-gas environments require performance beyond standard austenitics. 17-4PH round bars are used in the following 6 key industries and applications:

Subsea valve stems, manifold components, downhole tool shafts, NACE MR0175-compliant fasteners, and Christmas tree hardware.
In chloride-bearing process streams, the following bolts are of interest: those used with heat exchanger baffle assemblies, reactor vessel studs, pump shafts, and agitator shafts.
Propeller shafts, rudder pins, seawater pump shafts, and desalination plant hardware.
Digester hardware, bleach washer shaft fasteners, and chip pre-steaming vessel fasteners.
Fasteners for FGD scrubber shafts, cooling water pump components, and flue gas ductwork are of interest.
Structural fasteners for coastal bridges, reinforcement dowels in chloride-exposed concrete, and anchor bolts for marine structures.

How to Order Duplex Steel UNS S31803 Round Bar from Nicorex Alloys

To place an order for Duplex UNS S31803 round bars, the following 8 details must be specified:

Product form (round, hex, flat, square, forged bar)
Specification ASTM A276/A479 or A182 F51
Diameter, tolerance (H9–H12), and length
Condition solution annealed
Surface finish and quantity
Testing ASTM A923, Charpy impact, NACE compliance
Documentation EN 10204 3.1 MTC, ferrite count (40–60%)
Confirm if S32205 dual certification is required

Frequently Asked Questions

What is the Difference Between S31803 (F51) and S32205 (F60)?

S32205 is a tighter-chemistry version of S31803 with higher minimum Cr (22.0%), Mo (3.0%), and N (0.14%), resulting in a guaranteed PREN ≈ 35 versus ~30.5 for S31803. S32205 can be dual-certified to S31803, but not vice versa.

Can S31803 Bar be Used above 300°C?

Longer exposure above 300°C makes material susceptible to the formation of sigma phases and intermetallics, which can reduce both the robustness and the corrosion resistance of the material. For service above 300°C, using austenitic or nickel alloy alternatives.

Is Duplex S31803 Bar Magnetic?

Yes. The ferrite phase (approximately 50%) makes S31803 partially magnetic, distinguishing it from fully austenitic grades like 316L and 904L.

What Filler Metal is Recommended for Welding S31803 Bar?

ER2209 (AWS A5.9) or E2209 (AWS A5.4) matching duplex fillers are standard. These over-alloyed fillers provide sufficient austenite formation in the weld metal.

Can S31803 Round Bar be Cold Drawn for Tighter Tolerances?

Duplex S31803 round bar ranges from ₹450 to ₹900 per kg depending on diameter, finish, and mill origin. Forged F51 bar carries a 20–30% premium.

What is the Price of Duplex S31803 / F51 Round Bar per kg in India?

Yes. Cold-drawn S31803 bar is available in H9, H10, and H11 tolerances with bright or centreless-ground finish. Cold drawing increases yield above the annealed minimum but must stay within 293 HBW max.