Stainless Steel SS316L
Stainless Steel SS316L is a low-carbon variant of SS316, designed to offer superior corrosion resistance, especially after welding or exposure to high temperatures. The “L” stands for “Low Carbon”, typically containing less than 0.03% carbon, which minimizes carbide precipitation and helps prevent intergranular corrosion during welding.
SS316L retains all the benefits of SS316, including excellent resistance to chlorides, acids, and pitting corrosion, making it suitable for marine, chemical, pharmaceutical, and food processing industries. Its non-magnetic nature, combined with high strength and toughness, allows it to perform well even in cryogenic temperatures.
Overall, SS316L is highly valued for its durability, hygiene, and long service life in harsh and demanding environments.
Applications
Chemical & Petrochemical Industry: Storage tanks, heat exchangers, and process piping exposed to corrosive chemicals.
Marine Environments: Boat fittings, marine hardware, and coastal architectural components due to excellent saltwater resistance.
Food & Beverage Industry: Processing equipment, dairy machinery, and kitchen equipment where cleanliness is essential.
Pharmaceutical & Medical Sector: Surgical instruments, implants, and pharmaceutical processing systems for their biocompatibility and corrosion resistance.
Oil & Gas Industry: Offshore platforms, pipelines, and pressure vessels exposed to harsh and chloride-rich environments.
Architecture & Construction: Handrails, façade elements, and decorative panels in coastal regions.
Cryogenic Applications: Storage vessels and piping systems handling liquefied gases due to good toughness at low temperatures.
Chemical Composition
| Element | Carbon (C) | Chromium (Cr) | Nickel (Ni) | Molybdenum (Mo) | Manganese (Mn) | Silicon (Si) | Phosphorus (P) | Sulfur (S) | Nitrogen (N) | Iron (Fe) |
|---|---|---|---|---|---|---|---|---|---|---|
| Percentage (%) | ≤ 0.03 | 16.0 – 18.0 | 10.0 – 14.0 | 2.0 – 3.0 | ≤ 2.0 | ≤ 1.0 | ≤ 0.045 | ≤ 0.03 | ≤ 0.10 | Balance |
Hardness
Stainless Steel SS316L is a low-carbon, austenitic stainless steel known for its excellent toughness and corrosion resistance rather than extreme hardness. Its hardness can vary depending on the form and treatment:
Annealed Condition: Typically around 150–190 HB (Brinell Hardness) or approximately 80–95 HRB (Rockwell B).
Cold Worked Condition: Can reach up to 260–290 HB due to strain hardening.
Equivalent Grades
- European (EN) X2CrNiMo17-12-2
- UNS (Unified Numbering System) S31603
- AISI / SAE (USA) 316L
- BS (British Standard) 316S11 / 316S12
- JIS (Japan) SUS316L
- DIN (Germany) 1.4404 / 1.4435
- GOST (Russia) 03Х17Н14М3
Heat Treatment
1. Solution Annealing:
SS316L should be heated to a temperature range of 1010°C to 1120°C and then rapidly cooled (usually water quenched).
This process dissolves carbide precipitates and ensures maximum corrosion resistance.
2. Stress Relieving:
If the steel has undergone heavy machining or forming, it can be stress relieved by heating to 450°C to 600°C, followed by controlled air cooling.
This helps to minimize internal stresses without affecting its corrosion resistance.
3. Post-Weld Annealing:
Generally not required for SS316L because of its low carbon content, but may be used in critical applications to remove residual stress and restore optimum mechanical properties.
Hardening
SS316L cannot be hardened by conventional heat treatment methods because it is an austenitic stainless steel, which means it maintains its structure even when heated or cooled.
However, work hardening (cold working) can significantly increase its strength and hardness. During cold working processes such as rolling, drawing, or bending, the material’s dislocation density increases, which enhances hardness and tensile strength.
For applications requiring improved hardness or wear resistance, surface hardening techniques like nitriding, carburizing, or shot peening can be applied without compromising corrosion resistance.
Welding
Weldability: Excellent — can be welded using most conventional methods such as TIG (GTAW), MIG (GMAW), SMAW (Shielded Metal Arc Welding), and resistance welding.
Filler Material: For best results, use SS316L or SS316 filler rods/wires to maintain corrosion resistance.
Preheating/Post-heating: Not required; however, post-weld annealing may be used in critical applications to relieve residual stress and restore full corrosion resistance.
Precautions: Avoid excessive heat input and ensure proper shielding gas coverage to prevent oxidation and distortion.
Machinability
Machining Difficulty: Medium — SS316L tends to work harden quickly, requiring sharp cutting tools and proper cooling.
Cutting Tools: Use carbide-tipped or high-speed steel (HSS) tools with positive rake angles.
Coolant Use: Employ abundant coolant (preferably water-soluble cutting fluid) to prevent overheating and extend tool life.
Feeds and Speeds: Moderate feed rates and slower cutting speeds are recommended to minimize work hardening.
Surface Finish: Excellent finishes can be achieved with precision machining and controlled parameters.
Chip Formation: Produces long, tough chips — use chip breakers where possible.
✅ Summary:
Physical Properties
| Property | Value |
|---|---|
| Property | Value |
| Density | 8.0 g/cm³ |
| Melting Point | 1370 – 1400°C |
| Tensile Strength | 485 – 620 MPa |
| Yield Strength (0.2% Proof) | 170 – 310 MPa |
| Elongation | 40 – 50% |
| Modulus of Elasticity | 193 GPa |
| Thermal Conductivity | 16.3 W/m·K at 100°C |
| Specific Heat Capacity | 500 J/kg·K |
| Electrical Resistivity | 7.4 × 10⁻⁷ Ω·m |
| Magnetic Properties | Essentially non-magnetic in annealed condition; may become slightly magnetic after cold working |
Chemical Properties
| Property | Value |
|---|---|
| Corrosion Resistance | Excellent — outstanding resistance to corrosion in marine, acidic, and chloride environments due to molybdenum content. |
| Oxidation Resistance | Good — can withstand oxidation up to 870°C in continuous service and 925°C in intermittent service. |
| Acid Resistance | Highly resistant to sulfuric, hydrochloric, acetic, and tartaric acids under mild conditions. |
| Pitting and Crevice Corrosion Resistance | Excellent — superior to SS304 due to 2–3% molybdenum addition. |
| Stress Corrosion Cracking Resistance | Excellent — performs well under tensile stress in chloride-rich environments. |
| Scaling Resistance | Good — maintains surface stability under elevated temperatures. |
| Passivation | Forms a self-healing chromium oxide film, ensuring long-term corrosion resistance. |
Dealer
We supply and stock Stainless Steel SS316L in a variety of forms and sizes, catering to industries that require high corrosion resistance, excellent weldability, and long service life. As a trusted dealer, supplier, and stockist, we provide SS316L materials certified and sourced from reputed mills.