Corrosion Resistant Alloys
NAS 354N (UNS N08354) - Super Austenitic Stainless Steel
A highly corrosion-resistant austenitic stainless steel, NAS 354N (UNS N08354, ASME Code Case 2585) provides pitting corrosion resistance and crevice corrosion resistance on par with a nickel-based corrosion-resistant alloy, a step above conventional stainless steels. Nippon Yakin supplies this product in plate, sheet and strip forms.
Coil
Sheet
Plate
Chemical Composition
UNS N08354
| C | Si | Mn | P | S | Ni | Cr | Mo | N | |
|---|---|---|---|---|---|---|---|---|---|
| Min | ― | ― | ― | ― | ― | 34.0 | 22.0 | 7.0 | 0.17 |
| Max | 0.030 | 1.00 | 1.00 | 0.030 | 0.010 | 36.0 | 24.0 | 8.0 | 0.24 |
Physical Properties
| Specific heat (J/kg･K) | 419 | |
| Specific resistivity (μΩ･cm) | 102.6 | |
| Thermal conductivity (W/m･K) | 9.8 | |
| Coefficient of thermal expansion (10-6/℃) | 30–200℃ | 14.1 |
| 30–300℃ | 14.7 | |
| 30–400℃ | 15.2 | |
| Young's modulus (MPa) | 19.3 x 104 | |
| Ferromagnetism | None | |
| Melting point (℃) | 1362-1391 | |
Mechanical Properties
Mechanical Properties at Room Temperature
UNS N08354
| 0.2% proof stress (N/mm2) |
Tensile strength (N/mm2) |
Elongation (%) |
Hardness | |
|---|---|---|---|---|
| (Hv) | (HB) | |||
| ≥ 295 | ≥ 640 | ≥ 40 | ― | ― |
Examples
| 0.2% proof stress (N/mm2) |
Tensile strength (N/mm2) |
Elongation (%) |
Hardness | ||
|---|---|---|---|---|---|
| (Hv) | (HB) | ||||
| Cold-rolled sheet, 2-mm thick |
393 | 795 | 52 | 188 | 89 |
High-Temperature Strength
Corrosion Resistance
NAS 354N is high in both chromium and molybdenum content, which endow this stainless steel with excellent pitting corrosion and crevice corrosion resistance in high-chlorine environments. Its high nickel content also provides exceptional stress corrosion cracking resistance.
Pitting Corrosion Resistance
Stress Corrosion Cracking Resistance
| Conditions | Occurrence of SCC | |
|---|---|---|
| MgCl2 | 20% Boil, 300hr | NO SCC |
| 25% Boil, 300hr | NO SCC | |
| 30% Boil, 300hr | NO SCC | |
| 35% Boil, 300hr | NO SCC | |
| 42% Boil, 300hr | NO SCC | |
Test conditions: U-bend test piece, 2-mm thick, #500 finish
Workability
Although NAS 354N can be hot- and cold-worked much like standard austenitic stainless steels such as SUS 304 and SUS 316, the high strength of the alloy must be kept in mind when doing so.
Weldability
Our NAS 354N alloy can be shield metal arc welded, TIG welded and plasma welded much as any standard austenitic stainless steel. We recommend using Hastelloy® C-type welding consumables with this product.
Machinability
As with any stainless steel endowed with a high nickel content, machining NAS 354N is more challenging than standard austenitic stainless steels, though NAS 354N is more easily handled than other nickel-based alloys. We recommend the use of an cemented carbide tool, and suggest combining a slower feed rate with a greater cutting depth.
Heat Treatment
As NAS 354N is an austenitic stainless steel, the same sort of heat treatment may be used. We suggest water-cooled solution treatment in a range between 1125 and 1175℃.
Pickling
A mixture of nitric and hydrofluoric acids is used in pickling. To the extent that NAS 354N is more resistant to corrosion than SUS 304, descaling is more difficult. Alkaline immersion for a short time before acid pickling and shot blasting if possible are effective at descaling.
Applications
- Seawater environments: seawater heat exchangers, marine structures
- Garbage incineration: gasification fusion furnaces
- Food production plants: mayonnaise, dressing production equipment
- Sensors
* Hastelloy is a registered trademark of Haynes International, Inc.
