What is 1.4878 Stainless Steel?
Jan 14, 2026
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1.4878 stainless steel, commonly known as 321H or UNS S32109, is the high-carbon variant of the titanium-stabilized 321 austenitic stainless steel. The "H" designation indicates its enhanced high-temperature strength and creep resistance, making it suitable for structural applications at elevated temperatures such as superheaters, heat exchangers, and pressure vessels in power generation and petrochemical industries.
This high-temperature stabilized grade is standardized under key international systems.
| Standard | Equivalent Grade |
|---|---|
| EN (Europe) | 1.4878 |
| ASTM/AISI (USA) | 321H, UNS S32109 |
| JIS (Japan) | SUS321H |
| KS (Korea) | STS321H |
Its composition includes titanium for stabilization and controlled carbon for high-temperature strength.
| Element | C | Si | Mn | P | S | Cr | Ni | Ti |
|---|---|---|---|---|---|---|---|---|
| Content (%) | 0.04 - 0.10 | ≤ 0.75 | ≤ 2.0 | ≤ 0.045 | ≤ 0.03 | 17.0 - 19.0 | 9.0 - 12.0 | ≥ 4xC% |
It maintains good mechanical properties at both ambient and elevated temperatures.
| Property (Room Temp) | Yield Strength (Rp0.2) | Tensile Strength (Rm) | Elongation (A) | Hardness (HB) |
|---|---|---|---|---|
| Typical Value | ≥ 205 MPa | 500 - 750 MPa | ≥ 40% | ≤ 215 |
Key Characteristics and Applications of 1.4878 / 321H
Enhanced High-Temperature Strength: The controlled carbon range provides improved creep and stress rupture resistance at temperatures above 500°C compared to standard 321.
Resistance to Intergranular Corrosion: Titanium stabilization prevents chromium carbide formation in the sensitization temperature range (450–850°C), ensuring good corrosion resistance in welded and high-temperature service.
Good Oxidation Resistance: Suitable for continuous service up to about 900°C and intermittent service up to 925°C.
Primary Applications:
Power Generation: Superheater and reheater tubing, boiler components, and high-temperature headers.
Petrochemical: Catalytic converter shells, reformer tubes, and high-temperature process piping.
Aerospace: High-temperature engine and exhaust components.
Heat Exchangers: Tubing and plates in high-temperature service.
How does 321H (1.4878) differ from standard 321 (1.4541)?
The main difference is the carbon content specification. 321H has a controlled carbon range of 0.04–0.10% to ensure higher minimum carbon for improved high-temperature strength, while standard 321 has a maximum carbon limit of 0.08% with no minimum requirement. 321H is therefore specified in pressure vessel codes like ASME for applications where long-term creep resistance at elevated temperatures is critical.
Why is titanium used as a stabilizer in 321H?
Titanium has a strong affinity for carbon and forms stable titanium carbides, which prevent chromium from reacting with carbon to form chromium carbides at grain boundaries. This stabilization is crucial for maintaining corrosion resistance in the heat-affected zone after welding or during service in the sensitization temperature range, making 321H suitable for welded high-temperature components.
Looking for a Reliable Supplier of 1.4878 / 321H Stainless Steel?
GNEE Steel supplies high-temperature grade 321H (1.4878) stainless steel in tubular, plate, and bar forms, designed for demanding power, petrochemical, and aerospace applications. We provide full material traceability and certification to relevant standards. If you have any requirements, please feel free to contact us.
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