SUS304 (AISI304) vs SUS316 (AISI316) Stainless Steel: Key Differences and Properties
2025/9/29
Both SUS304 (American Standard AISI 304) and SUS316 (American Standard AISI 316) are austenitic stainless steels, but there are important differences in their properties. The main distinction is that SUS316 contains molybdenum (Mo), which enhances its corrosion resistance.
Characteristics of SUS304
SUS304 (AISI 304) is a representative austenitic stainless steel, accounting for 60% of total stainless steel production. It is versatile, easy to process at room temperature, and commonly used for pressing, drawing (cold processing), and welding.
Applications include:
Household items
Building interiors and exteriors
Factory equipment
It is sometimes labeled as 18Cr-8Ni because it contains 18% chromium and 8% nickel. The lower chromium and nickel content compared to other stainless steels makes it more economical and relatively inexpensive. Although it is non-magnetic, machining can sometimes transform part of its structure into martensite, causing slight magnetism.
Characteristics of SUS316
SUS316 (AISI 316) is a non-magnetic stainless steel with higher corrosion and pitting resistance than SUS304, thanks to the addition of molybdenum (Mo). Why it resists corrosion better:
Stainless steel resists rust because a thin oxide passive film forms on its surface.
Chromium enables this self-repairing film, but in chloride-rich environments (e.g., seawater), the film’s stability is reduced.
Adding molybdenum enhances the self-repairing ability, giving SUS316 superior resistance, especially against pitting corrosion (localized rust spots).
SUS316 contains more molybdenum and nickel than SUS304, which boosts resistance but increases cost. It is recommended for environments exposed to seawater, coastal air, or sea breezes, where corrosion risk is high. In harsher environments, stainless steels with even higher resistance than SUS316 may be required.
Comparison of characteristics between SUS304 and SUS316
The characteristics of each are briefly summarized in the table below. Please note that these are the relative characteristics of SUS304 and SUS316.
Corrosion Resistance | Magnetic | Processability | Price | |
SUS304 | Inferior | None※ | Excellent | Cheap |
SUS316 | Excellent | None | Inferior | Expensive |
※There is a possibility that the product may become magnetic due to machining.
Comparison of physical properties between SUS304 and SUS316
Chemical composition | Carbon (C) | Silicon (Si) | Manganese (Mn) | Phosphorus (P) | Sulfur (S) | Nickel (Ni) | Chromium (Cr) | Mo |
SUS304 | Less than 0.08 | Less than 1.00 | Less than 2.00 | Less than 0.045 | Less than 0.030 | 8.0-10.5 | 18.0-20.0 | – |
SUS316 | Less than 0.09 | Less than | Less than 2.01 | Less than 0.045 | Less than 0.030 | 10.0-14.0 | 16.0-18.0 | 2.0-3.0 |
Physical properties | Density (kg/ m3 ) | Modulus of elasticity (Gpa) | Specific electrical resistivity (room temperature) μΩ cm | Specific heat ((0-100℃) KJ/kg ・K) | Thermal conductivity ((100℃)W/m・K) | Thermal expansion coefficient (0~ |
SUS304 | 7930 | 193 | 72 | 0.5 | 16.3 | 17.3 |
SUS316 | 7980 | 193 | 74 | 0.5 | 16.3 | 15.9 |
Mechanical properties | Strength (N/m㎡) | Tensile strength (N/m㎡) | Stretch (%) | Aperture (%) | HB | HRB | HV |
SUS304 | More than 205 | More than 520 | More than 40 | More than 60 | Less than 187 | Less than 90 | Less than 200 |
SUS316 | More than 205 | More than 520 | More than 40 | More than 60 | Less than 187 | Less than 90 | Less than 200 |
Key Points
SUS316 contains molybdenum, giving it greater corrosion and pitting resistance than SUS304.
SUS304 may become magnetic after machining; SUS316 generally remains non-magnetic.
SUS316 is more expensive than SUS304 due to its alloying elements.
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If you’re unsure about material selection or machining methods, we offer complimentary consultations to help optimize your design and production. For any questions, please feel free to contact us.
