321 Steel and 316 Stainless Steel
The Difference Between 321 and 316 Stainless Steel
The main difference between 321 and 316 stainless steel lies in their alloying elements and the resulting properties. 316 stainless steel offers excellent corrosion resistance, particularly in chloride-rich environments, due to the addition of molybdenum. 321 stainless steel, on the other hand, contains titanium, which stabilizes it against intergranular corrosion at high temperatures, making it suitable for applications such as high-temperature exhaust systems.
Which is better, 304 or 316 stainless steel?
316 stainless steel is generally considered superior to 304 due to its greater corrosion resistance, especially in harsh environments. While both are austenitic stainless steels, 316 contains molybdenum, which significantly improves its resistance to chlorides and other corrosive substances. However, for general use and in applications where cost is a primary consideration, 304 is generally preferred.
321 vs 316 Stainless Steel – What's the Difference
| Feature | 316 Stainless Steel | 321 Stainless Steel |
|---|---|---|
| Core Advantage | Excellent corrosion resistance, especially against chlorides | Excellent high-temperature resistance and resistance to intergranular corrosion |
| Key Alloying Element | Molybdenum | Titanium |
| Best Working Environment | Marine environments, chemical processing, and food processing | High-temperature environments (425–850°C), such as exhaust systems and furnace parts |
| Weldability | Good, but thick sections may require post-weld annealing | Excellent, typically no post-weld heat treatment needed |
| Cost & Versatility | Usually higher (due to expensive molybdenum and nickel) | Usually lower (compared to 316) |
Chemical Composition of 321 vs 316 Stainless Steel
| Element | Grade 316 Stainless Steel | Grade 321 Stainless Steel |
|---|---|---|
| C | 0.08 max | 0.08 max |
| Mn | 2.00 max | 2.00 max |
| Si | 0.75 max | 0.75 max |
| P | 0.045 max | 0.045 max |
| S | 0.030 max | 0.030 max |
| Cr | 16.00 – 18.00 | 17.00 – 19.00 |
| Ni | 10.00 – 14.00 | 9.00 – 12.00 |
| Mo | 2.00 – 3.00 | – |
| Ti | – | 5 * C – 0.70 |
Physical Properties of 321 vs 316 Stainless Steel:
| Property | Grade 316 | Grade 321 |
|---|---|---|
| Density (g/cm³) | 7.98 | 7.92 |
| Melting Point (°C) | 1398 – 1420 | 1398 – 1420 |
| Specific Heat (J/kg·K) | 500 | 500 |
| Thermal Conductivity (W/m·K) | 16.2 | 16.3 |
| Electrical Resistivity (µΩ·m) | 740 | 720 |
| Modulus of Elasticity (GPa) | 193 | 193 |
| Poisson's Ratio | 0.3 | 0.3 |
| Thermal Expansion (10^-6/K) | 16.5 – 16.7 | 16.5 – 16.9 |
Mechanical Properties of 321 vs 316 Stainless Steel:
| Property | Grade 316 | Grade 321 |
|---|---|---|
| Tensile Strength (MPa) | 515 – 690 | 515 – 850 |
| Yield Strength (0.2% offset) (MPa) | 205 – 260 | 205 – 230 |
| Elongation (%) | 30 – 40 | 35 – 40 |
| Hardness (Brinell HB) | ≤ 217 | ≤ 217 |
Gnee Steel specializes in the production and sale of a wide range of stainless steel products, including 304, 316, 321, 904, 904L, 2205 Duplex, 2205 Duplex, and 316L stainless steel. Gnee Steel's products are widely used in the kitchen, aerospace, chemical, power, automotive, and nuclear energy sectors. We also provide custom stainless steel solutions tailored to customer needs. For stainless steel pricing or custom alloy solutions, please email ru@gneesteelgroup.com for a quote.