Related Specifications
Surface Treatments
Certifications
- ISO 9001 - 2015 Certified
- PED 2014/68/EC
- NACE MR0175/ISO 15156-2
- NORSOK M-650
- DFAR
- MERKBLATT AD 2000 W2/W7/W10
ASTM A1082/A1082M Grade S31803 | Duplex 2205 Stainless Steel
Superior corrosion resistance and high mechanical strength for demanding environments
Grade S31803 (UNS S31803) is the most widely used duplex stainless steel grade, commonly known as Duplex 2205, featuring a dual-phase microstructure of austenite and ferrite in roughly equal proportions. Designated as ASTM A1082/A1082M F51, this grade provides exceptional resistance to chloride stress corrosion cracking (SCC), pitting, and crevice corrosion, significantly outperforming standard austenitic grades like 316L. With 22% chromium, 3% molybdenum, and 5-6% nickel, S31803 offers high yield strength—nearly double that of austenitic stainless steels—making it ideal for oil and gas production, marine environments, chemical processing, and desalination plants. Its unique combination of corrosion resistance and high strength allows for reduced wall thickness and lighter-weight designs in pressure vessels, piping, and structural components.
ASTM A1082/A1082M Grade S31803 Chemical RequirementsA
| Grades | UNS Designation | Type | C | Mn | P | S | Si | Cr | Ni | Mo | N | Other ElementsB |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| ASTM A1082/A1082M Duplex (Ferritic-Austenitic) Grades | S31803 | . . . | 0.030 | 2.00 | 0.030 | 0.020 | 1.00 | 21.0-23.0 | 4.5-6.5 | 2.5-3.5 | 0.08-0.20 | . . . |
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ASTM A1082/A1082M Grade S31803 Mechanical Properties
| UNS Designation | Solution Temperature, °F [°C] (B, C) | Tensile Strength, min, ksi [MPa] | Yield Strength, 0.2% offset, min, ksi [MPa] | Elongation in 2" [50 mm] or 4D, min, % | Rockwell HRC, max | Brinell max (D) |
|---|---|---|---|---|---|---|
| S31803 | 1900 [1040] | 90 [620] | 65 [450] | 25 | 30 | 290 |
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ASTM A1082/A1082M Markings
| UNS Designation | Grade Symbol |
|---|---|
| S31803 | TB 31803 |
Frequently Asked Questions
What is Duplex 2205 (S31803)?
Duplex 2205 (S31803) is a stainless steel grade covered under ASTM A1082/A1082M for high-strength bolting in special-purpose applications such as pressure vessels. UNS designation S31803. Available as bolts, studs, screws and nuts manufactured by TorqBolt for global oil/gas/nuclear/power/marine sectors.
What are the mechanical properties of Duplex 2205 (S31803) per ASTM A1082?
Mechanical property requirements for S31803 are defined in ASTM A1082 Table 2 (PH grade solution treatment) or Table 4 (duplex annealed condition). Properties vary by treatment condition - refer to the bolting specification for the H-condition (PH) or annealed yield/tensile/elongation/hardness requirements applicable to your order.
Is Duplex 2205 (S31803) suitable for sour service (NACE MR0175)?
Refer to NACE MR0175 / ISO 15156 Tables A.16-A.19. Most A1082 duplex grades are permitted at ≤28 HRC; PH grades require condition-specific qualification (typically H1150 for 17-4 PH at 28 HRC). TorqBolt supplies sour-service certified product on request with full PMI + hardness traceability.
What ASME / ISO dimensional standards can Duplex 2205 (S31803) be supplied to?
This grade is available across the full ASME and ISO bolting dimensional standards covered on this site - ASME B18.2.1 (hex bolts, hex cap screws, lag screws), B18.2.2 (hex nuts, square nuts, lock nuts), B18.3 (socket head cap screws), B18.31.2 (clamping studs), B16.5 (flange stud bolts), ISO 4032 / 4033 / 4035 (metric nuts), and metric B18.2.3.xM / B18.2.4.xM series.
References & Standards
- ASTM A1082 / A1082M - Standard Specification for High-Strength Precipitation-Hardening and Duplex Stainless Steel Bolting for Special-Purpose Applications (current edition 2016, active)
- ASTM A962 / A962M - General Requirements for Special-Purpose Bolting Materials
- ASTM A370 - Mechanical Testing of Steel Products
- NACE MR0175 / ISO 15156 - Sour-service hardness limits for petroleum & natural gas industries
- ASME B18 series - Dimensional standards for bolts, screws, nuts, studs
- ISO 4032 / 4033 / 4035 - Metric hexagon nut dimensional standards
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