1. Standard Designations

• UNS: S31703

• ASTM: A240/A240M

• EURONORM: 1.4438

• JIS: SUS 317L

• GB/T: 022Cr19Ni13Mo4 (Approximately)

2. Chemical Composition (% by weight)

Note: The key differentiator from 316L is the significantly higher minimum Molybdenum content (3.0% vs. 2.0%), along with increased Chromium and Nickel.

3. Mechanical Properties (at Room Temperature, for Annealed Condition)

(Note: Mechanical properties are similar to 316L, but the enhanced corrosion resistance is the primary advantage.)

4. Physical Properties (Typical)

5. Corrosion Resistance

• Pitting & Crevice Corrosion: Superior to 316L. The higher Molybdenum content results in a higher Pitting Resistance Equivalent Number, providing excellent performance in chloride-containing solutions.

  • PREN = %Cr + 3.3×%Mo + 16×%N ≈ 29-33

• Stress Corrosion Cracking (SCC): Offers better resistance to chloride-induced SCC than 316L.

• General Corrosion: Excellent resistance to a wider range of corrosive chemicals, including sulfuric acid and phosphoric acid, particularly in moderate concentrations and temperatures.

• Intergranular Corrosion: The low carbon content provides excellent resistance in the as-welded condition.

6. Available Product Range (Plates)

7. Typical Applications

• Chemical Process Industry: Reactors, tanks, and piping for handling sulfuric and phosphoric acids.

• Pulp & Paper Industry: Digesters, bleach plants, and chemical recovery systems.

• Pollution Control: Flue Gas Desulfurization (FGD) systems and wastewater treatment equipment.

• Oil & Gas: Components exposed to sour gas (H₂S) and chlorides.

• Textile Industry: Equipment for chemical processing of fibers.