SUS304 vs SUS316 Stainless Steel: What’s the Difference?
Mar 28, 2025
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In the field of stainless steel materials, SUS304 and SUS316 are two widely used and highly regarded models. They are both austenitic stainless steels with common characteristics such as non-magnetic, good toughness and processing performance, but they differ in many key aspects.
SUS304 vs SUS316 Stainless Steel Chemical Composition
| Property | SUS304 (JIS G4303) | SUS316 (JIS G4303) |
|---|---|---|
| Chemical Composition | ||
| - Chromium (Cr) | 18.0–20.0% | 16.0–18.0% |
| - Nickel (Ni) | 8.0–10.5% | 10.0–14.0% |
| - Molybdenum (Mo) | Not Added | 2.0–3.0% |
| - Carbon (C) | ≤0.08% | ≤0.08% |
| - Manganese (Mn) | ≤2.0% | ≤2.0% |
| - Silicon (Si) | ≤1.0% | ≤1.0% |
| - Phosphorus (P) | ≤0.045% | ≤0.045% |
| - Sulfur (S) | ≤0.030% | ≤0.030% |
SUS304 vs SUS316 Stainless Steel Mechanical Properties
| Mechanical Properties | SUS304 (JIS G4303) | SUS316 (JIS G4303) |
|---|---|---|
| - Tensile Strength (MPa) | ≥520 | ≥520 |
| - Yield Strength (MPa) | ≥205 | ≥205 |
| - Elongation (%) | ≥40% | ≥40% |
| - Hardness (Rockwell B) | ≤92 | ≤95 |
| - Density (g/cm³) | 7.93 | 7.98 |
What is the difference in corrosion resistance between SUS304 and SUS316 stainless steel?
Both SUS304 and SUS316 are austenitic stainless steels, but SUS316 is significantly better than SUS304 in corrosion resistance due to the addition of 2-3% molybdenum (Mo). The core difference lies in the role of molybdenum: the molybdenum in SUS316 forms a denser oxide film (Cr₂O₃ + MoO₃), which effectively resists chloride ion (Cl⁻) corrosion, especially in chlorine-containing environments such as seawater and salt water. The ability to resist pitting and crevice corrosion is outstanding. SUS304 does not contain molybdenum and relies on the oxide film formed by chromium (Cr) and nickel (Ni). It performs well in ordinary atmosphere, fresh water or weak acidic environments, but is prone to corrosion in chloride environments.
SUS316 has excellent performance in harsh corrosive environments due to the advantages of molybdenum, but the cost is about 30-50% higher than SUS304. When choosing, you need to weigh the environmental corrosiveness, budget and equipment life requirements.
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