Stainless Steel S31200
UNS S31200
S31200 (UNS S31200, 44LN) is a first-generation duplex ferritic-austenitic stainless steel whose strength and corrosion performance are close to 2205.
Reference datasheet — S31200 is not in the instant-quote catalog. Upload your part and an engineer will quote it in this grade or suggest the closest stocked equivalent.
Values for the SA condition
S31200 tempers and conditions
S31200 is supplied in 4 conditions, soft to hard. SA is the default FabDigit quotes; the values on this page are for it.
Compare all 4 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Forged, Solution Annealed (ASTM A182 F-type duplex forging) | For flanges, valve bodies and heavy sections; requires post-forge solution anneal and rapid quench to dissolve sigma phase. | 510 | 750 | 30 | 23 HRC | 2.2 % IACS |
SADefault Solution Annealed | Standard supply condition for plate, pipe and bar — best balance of strength, ductility and corrosion resistance. | 530 | 770 | 32 | 24 HRC | 2.2 % IACS |
As-welded deposit | Reference condition for fabricated joints — properties of weld metal/HAZ when no post-weld solution anneal is performed. | 540 | 750 | 25 | 25 HRC | 2.2 % IACS |
Cold drawn | Choose for shafts, fasteners and machined fittings needing tighter tolerance and ~15–25 % higher yield than annealed. | 680 | 880 | 20 | 29 HRC | 2.2 % IACS |
Supply forms, finishes and certifications
Ways S31200 is supplied — form, process route, surface or paperwork — without a datasheet of their own. The property values above apply.
| Option | What it is | Type |
|---|---|---|
CR-SA-SHEET | Cold Rolled, Solution Annealed Sheet/Strip | Supply form |
HR-SA-PLATE | Hot Rolled, Solution Annealed and Pickled Plate | Supply form |
SMLS-SA-TUBE | Seamless Tube/Pipe, Solution Annealed | Supply form |
What is S31200?
S31200 (UNS S31200, 44LN) is a first-generation duplex ferritic-austenitic stainless steel whose strength and corrosion performance are close to 2205. It is chosen for chloride stress-corrosion cracking resistance in pressure equipment, with 530 MPa yield, 770 MPa tensile, 32 % elongation and 240 HB (24 HRC) in the solution-annealed condition, supplied as hot-rolled plate, cold-rolled sheet, seamless tube, cold-drawn and forged bar. Service is capped near 300 °C, thermal exposure between 300 and 1000 °C embrittles the structure, and mill availability is narrower than for S31803/S32205, which is the usual alternative. S31200 has a density of 7.8 g/cm³ (0.282 lb/in³), heavier than 50% of stainless steel grades. It melts at 1,385°C (2,525 °F). S31200 has a yield strength of 530 MPa (76.9 ksi) and a tensile strength of 770 MPa (112 ksi) — stronger than 81% of stainless steel grades. Elongation at break is 32% and the elastic modulus is 200 GPa (29 Msi).
What is S31200 used for?
- chemical process piping
- pressure vessels
- heat exchangers
Advantages
- Good corrosion resistance — 78/100, better than 84% of stainless steel grades
- High strength — 530 MPa (76.9 ksi), better than 81% of stainless steel grades
Limitations
- Limited service temperature — 300°C (572 °F), worse than 90% of stainless steel grades
S31200 properties
Typical room-temperature values for S31200-SA; bars are the position among stainless steel grades.
Physical3
S31200 has a density of 7.8 g/cm³ (0.282 lb/in³), heavier than 50% of stainless steel grades. It melts at 1,385°C (2,525 °F).
Mechanical17
S31200 has a yield strength of 530 MPa (76.9 ksi) and a tensile strength of 770 MPa (112 ksi) — stronger than 81% of stainless steel grades. Elongation at break is 32% and the elastic modulus is 200 GPa (29 Msi).
Thermal6
S31200 is rated for continuous service to 300°C (572 °F). It conducts heat at 15.5 W/m·K (8.96 BTU/hr·ft·°F), better than 53% of stainless steel grades. Thermal expansion is 13 µm/m·K (7.22 µin/in·°F).
Electrical3
S31200 conducts electricity at 2.2 % IACS, worse than 61% of stainless steel grades.
Chemical & Environmental3
Corrosion resistance is very good (78/100), better than 84% of stainless steel grades.
Sustainability4
Producing a kilogram of S31200 takes about 55 MJ of energy and emits 4.5 kg of CO₂ — more than 50% of stainless steel grades. Typical recycled content is 65%.
Manufacturability8
S31200's machinability is fair (35/100, better than 51% of stainless steel grades); weldability very good (70/100); formability fair (50/100).
Common Calculations5
Values are nominal handbook figures for design screening. Certified mill or lot data ships with every FabDigit order on request.
Strength versus weight in the stainless steel family
Yield strength against density for every stainless steel grade FabDigit runs. S31200 is highlighted; hover a dot for its name, or open the interactive family chart.
Working with S31200
Is S31200 easy to machine?
Machine like 2205: rigid setup, positive-rake carbide, ~25 % of 1212 speeds, heavy constant feed and flood coolant to avoid work hardening and glazing.
Can S31200 be welded?
Weldable by GTAW/GMAW/SMAW with 25Cr over-alloyed filler (e.g. ER2209/25.10.4L); keep heat input ~0.5–2.5 kJ/mm, interpass <150 °C, no preheat, back-purge with Ar (+N₂) and avoid PWHT unless full re-solution anneal is possible.
Can S31200 be formed, bent or molded?
Cold form with ~2× the force of 304 and allow for high springback; hot form 950–1150 °C followed by full solution anneal and water quench — never finish forming in the 300–1000 °C embrittlement range.
S31200 chemical composition (wt %)
Limits by weight percent from the governing specification, written the way the spec states them — a single maximum for impurities, a range for alloying elements, and the base element as balance. Nominal is the typical mid-range value.
| Element | Spec limit (wt %) | Nominal |
|---|---|---|
| Clow-carbon duplex | ≤ 0.03 | 0.02 |
| Mn | ≤ 2 | 1.2 |
| Si | ≤ 1 | 0.5 |
| P | ≤ 0.05 | |
| S | ≤ 0.03 | |
| Cr | 24 – 26 | 25 |
| Ni | 5.5 – 6.5 | 6 |
| Mo | 1.2 – 2 | 1.7 |
| Naustenite stabiliser, boosts pitting resistance | 0.14 – 0.2 | 0.17 |
| Fe | balance |
What surface finishes work on S31200?
Pickle and passivate after welding or hot work (HNO₃/HF paste, per ASTM A380/A967); electropolishing gives the best chloride-service surface — anodizing does not apply.
Surface treatments FabDigit runs on stainless steel parts — pick them in the quote configurator or call them out on the drawing. Each links to its datasheet in the surface-finish library (thickness, specs, call-out, material verdicts).
Passivation
Organic Coating
Thermal Spray
Equivalent designations
Standards and trade names that resolve to Stainless Steel S31200 in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- Trade names
- 44LN
- Other
- 312
How much does S31200 cost?
S31200 is a premium-cost stainless steel ($$$), cheaper than about 51% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
S31200 — frequently asked
What is S31200 used for?
S31200 is typically used for chemical process piping, pressure vessels and heat exchangers. In short: 2205-equivalent duplex performance; high chloride SCC resistance; limited mill availability.
What is the yield strength of S31200?
S31200 has a typical yield strength of 530 MPa (76.9 ksi) and a tensile strength of 770 MPa (112 ksi) — stronger than 81% of stainless steel grades. Strength varies by condition: see the 4 listed tempers.
Is S31200 easy to machine?
Not especially — machinability is rated fair (35/100, better than 51% of stainless steel grades). Machine like 2205: rigid setup, positive-rake carbide, ~25 % of 1212 speeds, heavy constant feed and flood coolant to avoid work hardening and glazing.
Can S31200 be welded?
Yes — weldability is rated very good (70/100). Weldable by GTAW/GMAW/SMAW with 25Cr over-alloyed filler (e.g. ER2209/25.10.4L); keep heat input ~0.5–2.5 kJ/mm, interpass <150 °C, no preheat, back-purge with Ar (+N₂) and avoid PWHT unless full re-solution anneal is possible.
What surface finishes work on S31200?
Pickle and passivate after welding or hot work (HNO₃/HF paste, per ASTM A380/A967); electropolishing gives the best chloride-service surface — anodizing does not apply.
Can S31200 be formed, bent or molded?
Cold form with ~2× the force of 304 and allow for high springback; hot form 950–1150 °C followed by full solution anneal and water quench — never finish forming in the 300–1000 °C embrittlement range.
What is the maximum service temperature of S31200?
S31200 is rated for continuous use to about 300°C (572 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between S31200-SA and S31200-CD?
SA is the default condition — standard supply condition for plate, pipe and bar — best balance of strength, ductility and corrosion resistance. CD: choose for shafts, fasteners and machined fittings needing tighter tolerance and ~15–25 % higher yield than annealed. Yield strength is 530 MPa in SA versus 680 MPa in CD.
How much does S31200 cost?
S31200 is a premium-cost stainless steel ($$$), cheaper than about 51% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
Sources
- ASTM A240/A240M Standard Specification for Chromium and Chromium-Nickel Stainless Steel Plate, Sheet, and Strip — ASTM International (2023)
- ASTM A789/A790 Seamless and Welded Ferritic/Austenitic Stainless Steel Tubing and Pipe — ASTM International (2023)
- ASTM A182/A182M Forged or Rolled Pipe Flanges, Fittings, Valves and Parts — ASTM International (2022)
- ASM Handbook Vol.1 — Properties and Selection: Irons, Steels, and High-Performance Alloys (duplex stainless section) — ASM International (1990)
- Practical Guidelines for the Fabrication of Duplex Stainless Steels — IMOA / International Molybdenum Association (2014)
- 44LN / duplex 25Cr-6Ni-Mo-N alloy datasheet — Sandvik / Outokumpu (Avesta) (2020)
Property data is compiled from published supplier and standards handbooks and normalised for comparison; hardness values on non-Brinell scales are converted approximately for charting only. Manufacturability limits are FabDigit quote-engine defaults and may be relaxed by engineering review. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.