Austenitic 317LMN (UNS S31726) Stainless Steel Plate/Coil
Austenitic 317LMN (UNS S31726) Stainless Steel Plate/Coil: Properties, Equivalents & Applications
Detailed technical data for 317LMN (UNS S31726) stainless steel plate/coil per ASTM A240, including chemical composition, mechanical and physical properties, international equivalents, and typical applications in aggressive chemical and marine environments.
Hot rolling, cold rolling, solution annealing, pickling, skin passing
- Phone : +8618037372205
- Email : [email protected]
- WhatsApp: Contact via Whtsapp
- WeChat: +8618037372205
Austenitic 317LMN Stainless Steel Plate/Coil Introduction
Austenitic 317LMN (UNS S31726) is a low‑carbon, high‑molybdenum, nitrogen‑enhanced austenitic stainless steel primarily supplied as plate, sheet and coil. The deliberate addition of nitrogen provides higher strength and substantially improved resistance to pitting and crevice corrosion in chloride‑containing media compared to standard 317L.
- Excellent resistance to sulphuric, phosphoric, and acetic acids
- Superior chloride pitting resistance (PREN ≥ 33)
- High proof strength combined with good ductility and weldability
- Non‑magnetic in the solution‑annealed condition
- Used where 316L or 317L are insufficient
Typical delivery condition is solution annealed and pickled or bright annealed. The steel is produced in accordance with ASTM A240/A240M and widely used in chemical tanks, flue gas desulphurisation scrubbers, heat exchangers, and marine equipment.
Austenitic 317LMN Stainless Steel Plate/Coil Chemical Composition
Chemical composition per ASTM A240/A240M for UNS S31726. The low carbon content minimises sensitisation during welding, while molybdenum and nitrogen enhance pitting and crevice corrosion resistance. All values are ladle analysis.
| Element | Content (wt %) | Notes |
|---|---|---|
| Carbon (C) | ≤ 0.030 | |
| Manganese (Mn) | ≤ 2.00 | |
| Phosphorus (P) | ≤ 0.045 | |
| Sulfur (S) | ≤ 0.030 | |
| Silicon (Si) | ≤ 0.75 | |
| Chromium (Cr) | 17.0 – 20.0 | Key to passivity and oxidation resistance |
| Nickel (Ni) | 13.5 – 17.5 | Stabilises austenite and enhances formability |
| Molybdenum (Mo) | 4.0 – 5.0 | Crucial for chloride pitting resistance |
| Nitrogen (N) | 0.10 – 0.20 | Strengthens matrix and improves pitting resistance |
| Iron (Fe) | Balance |
Austenitic 317LMN Stainless Steel Plate/Coil Thermal and Electrical Physical Properties
Typical physical property data for grade 1.4439 (EN 10088‑1:2014), which is technically equivalent to UNS S31726. These values are representative for solution‑annealed material and may vary slightly depending on exact composition and processing.
| Property | Typical Value | Unit | Test Condition / Temperature |
|---|---|---|---|
| Density (ρ) | 8.0 | g/cm³ | 20 °C |
| Modulus of Elasticity (E) | 200 | GPa | 20 °C |
| Shear Modulus (G) | 77 | GPa | 20 °C |
| Poisson's Ratio (ν) | 0.30 | — | 20 °C |
| Thermal Expansion Coefficient (α) | 16.0 | 10⁻⁶/K | 20 – 100 °C |
| Thermal Expansion Coefficient (α) | 16.5 | 10⁻⁶/K | 20 – 200 °C |
| Thermal Expansion Coefficient (α) | 17.0 | 10⁻⁶/K | 20 – 300 °C |
| Thermal Expansion Coefficient (α) | 17.5 | 10⁻⁶/K | 20 – 400 °C |
| Thermal Expansion Coefficient (α) | 18.0 | 10⁻⁶/K | 20 – 500 °C |
| Thermal Conductivity (λ) | 15 | W/(m·K) | 20 °C |
| Specific Heat Capacity (cp) | 500 | J/(kg·K) | 20 °C |
| Electrical Resistivity (ρe) | 0.85 | µΩ·m | 20 °C |
Austenitic 317LMN Stainless Steel Plate/Coil Mechanical Properties
Room‑temperature tensile properties according to ASTM A240/A240M for plate/coil in the solution‑annealed condition. Actual values are typically higher due to the nitrogen addition; for design, use the certified mill test report values.
| Property | Minimum Required Value | Unit | Test Condition |
|---|---|---|---|
| Tensile Strength (Rm) | 515 | MPa | Solution annealed, transverse |
| Yield Strength (Rp0.2) | 205 | MPa | Solution annealed, transverse |
| Elongation (A) | 40 | % | Gauge length 50 mm (2 in.), solution annealed |
| Hardness | 95 HRBW / 217 HBW | (max) | Solution annealed |
Austenitic 317LMN Stainless Steel Plate/Coil Fully Equivalent Material Standards and Replaceable Grades
| Country / Region | Standard | Grade | Remarks |
|---|---|---|---|
| USA | ASTM A240/A240M | UNS S31726 | Base specification for plate/coil |
| European Union | EN 10088-2 | 1.4439 (X2CrNiMoN17-13-5) | Identical chemistry, widely used |
| International | ISO 15510 | X2CrNiMoN17-13-5 | Unified grade designation |
| China | GB/T 24511 / GB/T 20878 | S31726 (022Cr19Ni16Mo5N) | Domestic pressure vessel and general use |
Austenitic 317LMN Stainless Steel Plate/Coil Application Introduction
317LMN is selected when standard 316L or 317L do not provide sufficient resistance to pitting, crevice corrosion, or acid attack. Its nitrogen‑enhanced strength often allows lighter wall thicknesses compared to 317L. It is fully weldable with matching or over‑alloyed fillers and generally requires no post‑weld heat treatment for thin sections, though solution annealing optimises corrosion performance.
Product Applications: Welded and seamless heat exchanger tubes, Storage tanks and process vessels, Piping systems for corrosive chemicals, FGD absorber internals and outlet ducts, Condenser and evaporator shells, Desalination plant components
Processed into products: Tube sheets and baffles, Flanges and spectacle blinds, Pump impellers and casings, Valve bodies and trim, Agitator blades and shafts, Scrubber spray nozzles
Application industries: Chemical processing (sulphuric, phosphoric, acetic acid plants), Flue gas desulphurisation (FGD) scrubbers, Pulp and paper bleach plants, Marine and offshore equipment, Pharmaceutical and bioprocessing, Food and beverage processing, Heat exchanger and condenser manufacturing
Austenitic 317LMN Stainless Steel Plate/Coil Similar / Alternative Material Recommendations
| Country / Region | Standard | Grade | Remarks |
|---|---|---|---|
| USA | ASTM A240 | 317L (UNS S31703) | Lower strength, similar corrosion resistance but less PREN; no intentional N addition |
| USA | ASTM A240 | 316L (UNS S31603) | Lower Mo (2‑3%), inferior chloride resistance; general purpose |
| EU | EN 10088-2 | 1.4404 / 1.4432 | 316L / 316L‑mod., less alloyed, for less aggressive media |
| Global | ASTM / EN | S31254 / 1.4547 (254 SMO) | Super‑austenitic, >6% Mo, N, higher PREN, more expensive |
| Global | ASTM / EN | S32205 / 1.4462 (2205) | Duplex, strength + chloride SCC resistance, not interchangeable in all services |
Notes:
Welding: Use filler metals AWS ER317L or EN ISO 14343 19 13 4 N L. Low heat input and interpass temperature <150 °C recommended. Corrosion: PREN = %Cr + 3.3×%Mo + 16×%N ≈ 33‑35 under the formula per ASTM A240; provides excellent resistance in near‑neutral and acidic chloride solutions. Post‑fabrication: Light cold working raises strength; full solution annealing at 1080‑1150 °C followed by rapid water quenching restores optimum corrosion resistance. The grade is non‑magnetic in the annealed condition but may become slightly magnetic after extensive cold working.
- Share
