What material is equivalent to AISI 321H?
Nov 10, 2025
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What is AISI 321H material?
AISI 321H is a high-carbon austenitic stainless steel that has undergone titanium stabilization treatment. It exhibits excellent resistance to intergranular corrosion, making it ideal for high-temperature applications. The added titanium prevents chromium carbide precipitation, while the higher carbon content improves creep resistance and strength at high temperatures. It typically operates in a temperature range of 427 to 816°C (800 to 1500°F). This steel is widely used in pressure vessels, chemical equipment, and aerospace components.
What material is equivalent to AISI 321H?
Materials equivalent to AISI 321H include UNS S32109 and the European designation 1.4878. It is important to distinguish 321H from 321, as the former has a higher minimum carbon content, which increases its strength at high temperatures.
| EU EN |
USA - |
Japan JIS |
France AFNOR |
England BS |
Italy UNI |
Sweden SS |
Russia GOST |
Inter ISO |
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| X8CrNiTi18-10 (1.4878) |
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Chemical Composition
The chemical composition of Grade 321H stainless steel is outlined in the following table.
| Element | Content (%) |
|---|---|
| Iron, Fe | Balance |
| Chromium, Cr | 17-19 |
| Nickel, Ni | 9-12 |
| Manganese, Mn | 2 |
| Silicon, Si | 1 |
| Titanium, Ti | 0.35 |
| Phosphorous, P | 0.045 |
| Carbon, C | 0.04-0.10 |
| Sulfur, S | 0.03 |
Mechanical properties
The mechanical properties of Grade 321H stainless steel are displayed in the following table.
| Properties | Metric | Imperial |
|---|---|---|
| Tensile strength | 480 MPa | 69600 psi |
| Yield strength | 205 MPa | 29700 ksi |
| Elongation at break | 29% | 29% |
| Hardness, Brinell | ≤187 | ≤187 |
Applications
The following are some of the major applications of Grade 321H stainless steel:
Aircraft exhaust stacks and manifolds
Jet engine parts
Weld equipment
Chemical processing equipment.
What are the differences between 321H and 347H?
The main difference lies in the stabilizing elements: 321H uses titanium as a stabilizing element, while 347H uses niobium (Niobium) and tantalum as stabilizing elements. Due to its higher niobium carbide stability, 347H is more suitable for high-temperature and heavy-duty welding applications. Both are high-carbon (H) versions of their base steel grades, meaning they have a higher carbon content, which improves high-temperature creep strength and performance.
| Feature | 321H Stainless Steel | 347H Stainless Steel |
|---|---|---|
| Stabilizing Element | Titanium (Ti) | Niobium (Nb) and Tantalum (Ta) |
| High-Temperature Performance | Good, but 347H is superior | Excellent, especially at sustained high temperatures |
| Corrosion Resistance | Excellent resistance to sensitization during welding | Superior resistance to intergranular corrosion at high temperatures, especially in heavy-welded parts |
| Application suitability | Suitable for applications where annealing after welding is not possible and can be used in similar applications to 304L for high-temperature strength | Ideal for heavy welded parts that cannot be re-annealed and applications requiring higher temperature creep strength, like aero engine parts and high-pressure steam pipes |
| Carbon content | Higher carbon content (0.04–0.10%) for improved high-temperature performance compared to standard 321 | Higher carbon content (0.04–0.10%) for improved high-temperature performance |
If you have any project requirements for 321H 1.4878 stainless steel pipes, please feel free to place an order. GNEE has a large inventory of popular products for your selection. They can be processed into various practical product forms, including plates, coils, pipes, bars, and wires. For detailed chemical composition and free samples, please contact our factory immediately. We offer competitive prices and excellent service.Email: sales@gneestainless.com
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