SS 321 vs. SS 321H: key differences
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SS 321 vs. SS 321H: key differences
What is SS 321 (UNS S32100, EN 1.4541)?
SS 321 (UNS S32100, EN 1.4541) is a titanium-stabilized austenitic stainless steel, an improved version of 304 stainless steel, and is ideal for applications requiring resistance to intergranular corrosion in continuous use environments between 400-800°C. Therefore, it is very suitable for use in exhaust systems, chemical processing, and aircraft components.
What is SS 321H (UNS S32109)?
SS 321H (UNS S32109) is a high-carbon, titanium-stabilized austenitic stainless steel with enhanced creep resistance and high-temperature strength. Its titanium content prevents the formation of chromium carbides during welding, making it resistant to intergranular corrosion even when exposed to temperatures of 800-1500°F (427-816°C). It is suitable for applications requiring high-temperature strength, such as aerospace components, chemical equipment, and expansion joints.
SS 321 vs. SS 321H: key differences
The main difference between SS 321 and SS 321H lies in their carbon content: 321 has a maximum carbon content of 0.08%, while 321H has a higher carbon content range (0.04-0.10%), making it ideal for use in harsh environments above 1000°F (538°C), while 321 is suitable for general high-temperature applications. Both are titanium-stabilized austenitic stainless steels, but the higher carbon content of 321H gives it better performance at extreme high temperatures.
SS 321 vs. SS 321H: Chemical Composition Table (ASTM A240)
| Element | SS 321 | SS 321H |
|---|---|---|
| Carbon (C) | ≤ 0.08% | 0.04–0.10% |
| Chromium (Cr) | 17.0–19.0% | 17.0–19.0% |
| Nickel (Ni) | 9.0–12.0% | 9.0–12.0% |
| Titanium (Ti) | ≥ 5×C% | ≥ 4×C% (meets Ti stabilization) |
| Manganese (Mn) | ≤ 2.0% | ≤ 2.0% |
| Silicon (Si) | ≤ 0.75% | ≤ 0.75% |
| Phosphorus (P) | ≤ 0.045% | ≤ 0.045% |
| Sulfur (S) | ≤ 0.030% | ≤ 0.030% |
| Iron (Fe) |
Bala nce |
Balance |
SS 321 vs. SS 321H:Mechanical Properties
| Property | SS 321 | SS 321H |
|---|---|---|
| Tensile Strength | ≥ 515 MPa | ≥ 515–550 MPa |
| Yield Strength | ≥ 205 MPa | ≥ 205–230 MPa |
| Elongation | ≥ 40% | ≥ 40% |
| Hardness | ≤ 217 HB | ≤ 217 HB |
| Creep Strength at 600–800°C | Good | Excellent |
| Max Continuous Temperature | ~900°C | ~950°C |
SS 321 vs. SS 321H: High temperature resistance
Due to its higher carbon content, SS 321H offers superior high-temperature performance compared to SS 321, resulting in higher thermal strength and creep resistance at temperatures above 1000°F (537°C). Both grades of stainless steel are stabilized with titanium, providing excellent resistance to intergranular corrosion after welding. However, the higher carbon content in 321H is specifically designed for higher-temperature applications where the performance of 321 may not be sufficient.
SS 321 vs. SS 321H:Application
| Application / Industry | SS 321 | SS 321H |
|---|---|---|
| Welded components | ★★★★★ | ★★★★☆ |
| Heat exchangers | ★★★★☆ | ★★★★★ |
| High-temperature pressure vessels | ★★★☆☆ | ★★★★★ |
| Exhaust systems | ★★★★☆ | ★★★★☆ |
| Furnace & thermal equipment | ★★★★☆ | ★★★★★ |
| Piping at 500–800°C | ★★★★☆ | ★★★★★ |
| Cryogenic service | ★★★★☆ | ★★★☆☆ |
GNEE currently has SUS 321 (UNS S32100) products in stock, including: plates, sheets, coils, strips, tubes, bars, and wires. In addition, we offer a variety of surface finishes for you to choose from, such as: No.1, 2B, 2D, BA, No.3, No.4, HL, No.8, sandblasting, etc.
We guarantee 100% quality. We will never deliver any defective products to our customers. Please contact us to customize your required product specifications, including shape, condition, surface treatment, and processing technology.
