SUS304 vs 316L: Corrosion resistance, how to choose?
Leave a message
SUS304 vs 316L: Corrosion resistance
| Grade | Critical Alloying Elements | Corrosion-Resistant Edge |
|---|---|---|
| SUS304 | 18Cr-8Ni | Basic oxidation resistance in weak acids. |
| 316L | 16Cr-10Ni-2Mo | Molybdenum (Mo) enhances chloride resistance. |
Why Mo Matters: Molybdenum forms a denser protective oxide layer, making 316L 3-5 times more durable than SUS304 in chloride environments (ASTM B117 salt spray test data).
SUS304 vs316L: Performance advantages
Chloride Exposure (Most Severe Test)
SUS304: Marine applications: Lifespan of 2-3 years (requires frequent maintenance).
Swimming pool equipment: Prone to pitting at pH <6.5.
316L:Ocean structures: Lasts 10-15 years (e.g., Singapore's Marina Bay metalworks).
Medical implants: ISO 13485-certified for body fluid resistance.
Acid/Alkali Resistance
SUS304:Withstands 5% sulfuric acid for 300 hours at room temperature (ASTM G31).
Limited to <60°C in strong alkalis (e.g., NaOH).
316L:Survives 5% sulfuric acid for 1,000+ hours.
Resists boiling nitric acid (≤70%)-ideal for chemical reactors.
High-Temperature Oxidation
SUS304: Max operating temp 870°C; prone to scaling over time.
316L: Handles 1,200°C-perfect for furnace parts and exhaust systems.
Cost and Machinability
Price gap: 316L is 15-25% more expensive than SUS304 (market price in 2025).
Machining:
316L requires specialized welding rods (e.g. ER316L) and careful heat control.
SUS304 is easier to form into complex shapes (e.g. vacuum flask lining).
