STS316 VS. SUS316 Stainless steel: Chlorine corrosion resistance
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STS316 vs. SUS316 Stainless Steel: Comparison of Chloride Corrosion Resistance
1.Grade Definitions and Standards
SUS316: An austenitic stainless steel grade defined under the Japanese JIS standard (JIS G4303/G4304), widely used in corrosion-resistant applications.
STS316: The equivalent grade under the Korean KS standard (KS D3551). Its chemical composition and properties are essentially the same as SUS316, and it belongs to the internationally recognized 316 stainless steel family (equivalent to ASTM A240/A276 Type 316 in the United States).
2. Chemical composition comparison
The core alloy elements of the two are the same, both containing 16-18% Cr, 10-14% Ni, and 2-3% Mo. The only difference is the control of trace impurities of different standards (such as C, Si, and Mn ranges). However, the Mo content, which plays a key role in chloride ion corrosion resistance, is exactly the same, so there is no significant difference in corrosion resistance.
Chemical Composition and Functions of SUS316 (JIS) vs. STS316 (KS) Stainless Steel
| SUS316 (JIS Standard) | STS316 (KS Standard) | ||
|---|---|---|---|
| Less than or equal to 0.08% | Less than or equal to 0.08% | ||
| 16.0–18.0% | 16.0–18.0% | ||
| 10.0–14.0% | 10.0–14.0% | ||
| 2.0–3.0% | 2.0–3.0% | A critical alloying element that strengthens the passive film, specifically resisting chloride-induced pitting and crevice corrosion. |
3. Chloride ion corrosion resistance
Anti-pitting and crevice corrosion: Type 316 stainless steel contains Mo, so its resistance to pitting and crevice corrosion is significantly better than that of Type 304 stainless steel (without Mo) in environments containing chloride ions (such as seawater, salt solutions, and bleach).
Applicable scenarios: Both are suitable for environments with medium chloride ion concentrations (such as Less than or equal to 1000 ppm) and temperatures Less than or equal to 60 degree , such as seawater desalination equipment, chemical pipelines, food processing equipment, etc.
SUS316 is more widely used in Asia (Japan and China), while STS316 is commonly used in South Korea and some Southeast Asian markets, but the two are interchangeable in international projects.
4. Key influencing factors
<500 ppm): Both perform well and there is no obvious corrosion after long-term use.
Medium to high concentration (500-3000 ppm): Temperature needs to be controlled ( Less than or equal to 60 degree ) and crevice structures need to be avoided, otherwise pitting may occur.
High concentration (>3000 ppm, such as about 20,000 ppm in seawater): It is necessary to upgrade to stainless steel with a higher molybdenum content (such as 317L, 2205 duplex steel).
Temperature: High temperature (>60 degree ) will accelerate the damage of chloride ions to the passivation film, which needs to be evaluated in combination with specific working conditions.
