Stainless Steel 317L
Stainless Steel 317L (UNS S31703 / EN 1.4438) – Specifications, Properties and Applications
Stainless Steel 317L (UNS S31703 / EN 1.4438) is a low-carbon, molybdenum-bearing austenitic stainless steel developed for applications requiring superior corrosion resistance in aggressive chemical and industrial environments.
Compared with Stainless Steel 316L, Grade 317L contains higher levels of chromium and molybdenum, providing improved resistance to pitting, crevice corrosion, and chemical attack in many demanding service conditions. Its low carbon content also reduces the risk of chromium carbide precipitation during welding, making it suitable for welded equipment.
Stainless Steel 317L is widely used in chemical processing, petrochemical plants, pharmaceutical manufacturing, pulp and paper production, water treatment, power generation, and industrial process equipment.
Emirerri Steel supplies Stainless Steel 317L in sheets, plates, coils, pipes, tubes, round bars, flanges, and pipe fittings for projects across Tunisia, Algeria, Morocco, Libya, and international markets.
Key Features
- Excellent corrosion resistance
- Higher molybdenum content than 316L
- Improved resistance to pitting corrosion
- Good resistance to crevice corrosion
- Excellent resistance in many chloride-containing environments
- Good resistance to aggressive chemicals
- Low carbon content
- Good resistance to intergranular corrosion after welding
- Excellent weldability
- Good formability
- High durability
- Long service life
Specifications
| Specification | Details |
|---|---|
| Grade | Stainless Steel 317L |
| UNS Number | S31703 |
| Werkstoff Number | 1.4438 |
| EN Designation | X2CrNiMo18-15-4 |
| Stainless Steel Family | Austenitic Stainless Steel |
| Common Standards | ASTM A240, ASTM A276, ASTM A312, ASTM A182, EN 10088 |
| Supply Condition | Solution Annealed |
| Surface Finishes | No.1, 2B, BA, No.4, Mirror |
| Product Forms | Sheet, Plate, Coil, Pipe, Tube, Round Bar, Flanges, Pipe Fittings |
Equivalent Grades
| Standard | Equivalent Grade |
|---|---|
| ASTM | 317L |
| UNS | S31703 |
| EN | 1.4438 |
| DIN | X2CrNiMo18-15-4 |
| JIS | SUS317L* |
| ISO | X2CrNiMo18-15-4 |
*Exact equivalence should be confirmed according to product form and applicable standard.
Available Sizes
Sheets & Plates
- Thickness: 0.5 to 100 mm
- Width: Up to 2500 mm
- Length: Up to 12000 mm
Pipes & Tubes
- Outside Diameter: 6 to 610 mm
- Wall Thickness: 0.5 to 40 mm
Round Bars
Diameter: 6 to 500 mm
Actual availability depends on product form, manufacturing standard, supply condition, and project requirements.
Stainless Steel 317L Chemical Composition
| Element | Composition (%) |
|---|---|
| Chromium (Cr) | 18.0 – 20.0 |
| Nickel (Ni) | 11.0 – 15.0 |
| Molybdenum (Mo) | 3.0 – 4.0 |
| Carbon (C) | ≤ 0.030 |
| Manganese (Mn) | ≤ 2.00 |
| Silicon (Si) | ≤ 1.00 |
| Phosphorus (P) | ≤ 0.045 |
| Sulfur (S) | ≤ 0.030 |
| Nitrogen (N) | ≤ 0.10 |
| Iron (Fe) | Balance |
Stainless Steel 317L Mechanical Properties
Values can vary according to product form and applicable specification.
| Property | Minimum Value |
|---|---|
| Tensile Strength | ≥ 515 MPa |
| Yield Strength (0.2% Offset) | ≥ 205 MPa |
| Elongation | ≥ 40% |
| Hardness | ≤ 217 HB |
| Modulus of Elasticity | ≈ 193 GPa |
Stainless Steel 317L Physical Properties
| Property | Approximate Value |
|---|---|
| Density | 8.00 g/cm³ |
| Melting Range | ≈ 1370 – 1400°C |
| Thermal Conductivity | ≈ 14.6 W/m·K |
| Specific Heat Capacity | ≈ 500 J/kg·K |
| Magnetic Permeability | Low in Annealed Condition |
Types of Stainless Steel 317L Products
Stainless Steel 317L Sheets & Plates
Used for chemical storage tanks, pressure vessels, process equipment, and industrial fabrication.
Stainless Steel 317L Pipes & Tubes
Suitable for chemical process piping, aggressive fluid transportation, petrochemical facilities, and industrial piping systems.
Stainless Steel 317L Heat Exchanger Tubes
Used in heat exchangers, condensers, and systems handling corrosive fluids.
Stainless Steel 317L Round Bars
Used for shafts, valves, pumps, fasteners, machined components, and industrial machinery.
Stainless Steel 317L Flanges & Pipe Fittings
Designed for piping systems requiring enhanced resistance to chemical corrosion.
Corrosion Resistance
Stainless Steel 317L provides excellent resistance to:
- General corrosion
- Pitting corrosion
- Crevice corrosion
- Chloride-containing environments
- Aggressive industrial atmospheres
- Many chemical process fluids
- Selected acidic environments
- Intergranular corrosion after proper welding
The higher molybdenum content of 317L provides improved localized corrosion resistance compared with conventional 304 and 316L stainless steels in many environments.
317L is often selected when 316L does not provide sufficient corrosion resistance. However, material selection should always be based on the actual chemical composition, concentration, temperature, and exposure conditions.
Heat Resistance
Stainless Steel 317L provides good oxidation resistance and maintains useful mechanical properties at elevated temperatures.
It is suitable for moderate-temperature industrial applications, but it is not primarily designed as a high-temperature stainless steel.
For applications involving prolonged exposure to extremely high temperatures, specialized grades such as Stainless Steel 310S may provide better performance.
Heat Treatment
Solution Annealing
- Temperature: Generally 1010 – 1120°C
- Cooling: Rapid cooling according to the applicable product specification
Objectives
- Restore corrosion resistance
- Improve ductility
- Relieve internal stresses
- Optimize microstructure
Stainless Steel 317L cannot be hardened by conventional heat treatment but can be strengthened through cold working.
Welding
Stainless Steel 317L has good to excellent weldability using conventional welding processes.
Recommended Welding Methods
- GTAW / TIG
- GMAW / MIG
- SMAW
- SAW
- Orbital Welding
- Resistance Welding
Welding Advantages
- Excellent weld quality
- Good mechanical strength
- Low carbon content
- Good corrosion resistance after welding
- Reduced risk of intergranular corrosion
Post-weld cleaning, pickling, and passivation are recommended where required to restore the surface condition and corrosion resistance.
Fabrication
Machining
- Turning
- Milling
- Drilling
- Threading
Forming
- Cold bending
- Roll forming
- Press forming
- Deep drawing
- Cold forming
Cutting
- Laser cutting
- Plasma cutting
- Waterjet cutting
- Mechanical sawing
Surface Finishing
- Pickling
- Passivation
- Mechanical polishing
- Electropolishing
- Brushing
Applications
Chemical Industry
- Chemical storage tanks
- Reactors
- Process piping
- Pressure vessels
- Chemical processing equipment
Petrochemical Industry
- Refineries
- Process piping
- Heat exchangers
- Chemical processing equipment
Pharmaceutical Industry
- Processing vessels
- Storage tanks
- Production equipment
- Process piping
Pulp & Paper Industry
- Process equipment
- Storage tanks
- Piping systems
- Bleaching equipment
Water Treatment
- Water treatment equipment
- Filtration systems
- Chemical treatment systems
- Desalination equipment
Power Generation
- Heat exchangers
- Cooling systems
- Industrial piping
- Auxiliary equipment
Stainless Steel 317L for Tunisia, Algeria, Morocco & Libya
Stainless Steel 317L is suitable for industrial projects across Tunisia, Algeria, Morocco, and Libya where enhanced resistance to aggressive chemicals, chlorides, and localized corrosion is required.
It can be used in oil & gas, petrochemical, chemical processing, pharmaceutical, water treatment, pulp and paper, power generation, and industrial process applications.
For project selection, the material should be evaluated according to the operating temperature, pressure, chemical composition, concentration, pH, chloride level, and exposure time, together with the applicable project standard.
Conclusion
Stainless Steel 317L (UNS S31703 / EN 1.4438) is a low-carbon, molybdenum-bearing austenitic stainless steel offering superior corrosion resistance in many aggressive industrial environments.
Its combination of high chromium, nickel, and molybdenum content, together with low carbon, provides excellent resistance to localized corrosion, good weldability, and reliable long-term performance.
Available in sheets, plates, pipes, tubes, round bars, flanges, and pipe fittings, Stainless Steel 317L is a dependable material for demanding applications in chemical, petrochemical, pharmaceutical, pulp and paper, water treatment, and power-generation industries across Tunisia, Algeria, Morocco, Libya, and international markets.
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