High Quality Stainless Steel Sheets & Plates
321 / 321H • Formable • Ductile • Machinable
Get a QuoteStainless Steel 321 / 321H Explained
Stainless Steel 321 and 321H are titanium-stabilized austenitic stainless steels designed to resist intergranular corrosion and carbide precipitation during prolonged exposure to elevated temperatures. These grades maintain excellent mechanical strength, oxidation resistance, and structural stability in high-temperature environments. SS 321 is suitable for moderate high-temperature service, while SS 321H contains higher carbon for improved creep and rupture strength.
Typical applications of SS 321/321H include aircraft exhaust systems, automotive manifolds, heat exchangers, boiler components, petrochemical equipment, and thermal expansion joints. Their superior thermal stability and weldability make them highly reliable for cyclic heating and continuous high-temperature service.
321/321H STAINLESS STEEL SHEETS AND PLATES EQUIVALENT GRADES
| STANDARD | UNS | WNR. | JIS | EN |
|---|---|---|---|---|
| SS 321 | S32100 | 1.4541 | SUS 321 | X6CrNiTi8-10 |
| SS 321H | S32109 | 1.4878 | SUS 321H | X12CrNiTi8-9 |
SPECIFICATION OF STAINLESS STEEL 321/321H SHEETS AND PLATES
| Standard | ASTM A240 / ASME SA240 |
|---|---|
| Dimension Standard | JIS, AISI, ASTM, GB, DIN, EN, etc |
| Width | 1000mm, 1219mm, 1500mm, 1800mm, 2000mm, 2500mm, 3000mm, 3500mm, etc |
| Length | 2000mm, 2440mm, 3000mm, 5800mm, 6000mm, etc |
| Thickness | 0.3 mm to 120 mm |
| Form | Coils, Foils, Rolls, Plain Sheet, Shim Sheet, Perforated Sheet, Chequered Plate, Strip, Flats, Blank (Circle), Ring (Flange) etc. |
| Surface Finishing | Hot rolled plate (HR), Cold rolled sheet (CR), 2B, 2D, BA, NO.1, NO.4, NO.8, 8K, mirror, Chequered, embossed, hair line, sand blast, Brush, etching, SATIN (Met with Plastic Coated) etc. |
CHEMICAL COMPOSITION OF STAINLESS STEEL 321/321H SHEETS AND PLATES
| Grade | Cr% | Ni% | C% | Si% | Mn% | P% | S% | N% | Ti% | Fe |
|---|---|---|---|---|---|---|---|---|---|---|
| 321 | 17.0-19.0 | 9.0-12.0 | 0.08 max | 0.75 max | 2.0 max | 0.045 max | 0.030 max | 0.10 max | min:5*(C+N) | Balance |
| 321H | 17.0-19.0 | 9.0-12.0 | 0.04-0.10 | 0.75 max | 2.0 max | 0.045 max | 0.030 max | 0.10 max | min:5*(C+N) max:0.70 | Balance |
MECHANICAL PROPERTIES OF STAINLESS STEEL 321/321H SHEETS AND PLATES
| Grade | Tensile Strength (ksi) | Yield Strength (ksi) | Elongation (%) | Hardness (Brinell) MAX |
|---|---|---|---|---|
| 321/321H | 75 min | 30 min | 40 min | 217 |
💡 Practical Difference in Use
Use Stainless Steel 321 when: excellent resistance to intergranular corrosion is required in elevated temperature service with good weldability and oxidation resistance.
→ Example: exhaust systems, heat exchangers, expansion joints, and furnace components.
Use Stainless Steel 321H when: higher creep strength and better performance at elevated temperatures above 550°C are required for pressure and structural applications. → Example: superheater tubes, pressure vessels, high-temperature piping, and power plant equipment.
Applications of Stainless Steel 321 / 321H Sheets and Plates
Stainless Steel 321 and 321H are titanium-stabilized austenitic grades designed for high-temperature service where resistance to carbide precipitation and thermal stability are essential.
- Heat Exchangers: Excellent oxidation and creep resistance under continuous heat exposure.
- Thermal Processing Equipment: Maintains strength and corrosion resistance at elevated temperatures.
- Aerospace & Automotive: Widely used in exhaust and high-temperature structural parts.
When to Choose Stainless Steel 321 vs. 321H?
The selection mainly depends on operating temperature, structural load, and creep resistance requirements.
Choose SS 321 when:
- Excellent resistance to intergranular corrosion is required
- Good weldability without post-weld heat treatment is needed
- Operating temperatures are moderate to high
- Used in cyclic heating and cooling environments
- Fabrication ease is a primary requirement
- Long-term oxidation resistance is essential
Choose SS 321H when:
- Higher creep and stress rupture strength is required
- Service temperatures exceed 550°C
- Used in high-pressure and load-bearing equipment
- Superior high-temperature structural stability is essential
- Common in power generation and refinery heaters
- Better resistance to thermal deformation is needed
Industries That Use Stainless Steel 321 / 321H Sheets and Plates
These grades are preferred in industries where high-temperature performance, oxidation resistance, and weld stability are critical.
Used in high-temperature and pressure systems.
Uses
Boiler tubing, superheaters, expansion joints.
Why SS 321/321H?
Excellent creep resistance and oxidation stability.
Essential for elevated temperature hydrocarbon processing.
Uses
Cracking units, heat exchangers, high-temperature piping.
Why SS 321?
Resists carbide precipitation during welding and service.
Used where thermal cycling and heat resistance are critical.
Uses
Jet engine exhausts, aircraft ducting systems.
Why SS 321?
Stable under extreme thermal fluctuations.
Used in high-temperature exhaust assemblies.
Uses
Manifolds, catalytic converter shells, exhaust pipes.
Why SS 321?
High resistance to oxidation and thermal fatigue.
Used in continuous furnaces and heating systems.
Uses
Furnace baskets, radiant tubes, heat shields.
Why SS 321H?
Superior strength retention at elevated temperatures.
Used in moderately corrosive high-temperature environments.
Uses
Reactors, distillation columns, hot process piping.
Why SS 321?
Prevents intergranular corrosion after welding.
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