Corrosion Resistant Alloys
NAS 255
- JISSUS 890L
- UNSN08904
- DIN/EN1.4539
NAS 255 (UNS N08904, SUS 890L) is an austenitic stainless steel with superior corrosion resistance in comparison with Type 316L. Due to addition of Cu (1.5%), this material displays excellent corrosion resistance against reducing acids such as sulfuric acid and phosphoric acid. It is used in chemical plants and a wide range of other applications. Nippon Yakin supplies this product in plate, sheet and strip form.
| Chemical Composition | 20Cr-24Ni-4.3Mo-1.5Cu |
|---|---|
| Product shape |
 Coil Sheet Plate |
| Workability | Cold and hot workability are approximately equal to those of Type 304, 316, and other standard austenitic stainless steels. |
| Weldability | Weldability is on the same level as ordinary austenitic stainless steels. Preheating and post-heating are not necessary. As welding electrodes, in applications under severe corrosion environments, use of welding consumables with equal or higher corrosion resistance is recommended. When the corrosion environment is not severe, and when the purpose of welding is for joining, matching welding consumables may be used. |
| Heat Treatment | Solution annealing of NAS 255 should be performed at 1095℃ and higher followed by being quenched in water or rapidly cooled by other means. (Conditions provided in ASTM A480/A480M) |
| Pickling | A mixture of nitric acid and hydrofluoric acid is used in pickling. However, due to the high corrosion resistance of NAS 255, scale is somewhat difficult to remove in comparison with Type 304. Therefore, the material should be immersed in an alkaline solution before pickling, or if possible, shot blasting is extremely effective. |
| Applications | Sulfuric acid and phosphoric acid plants, seawater heat exchangers, chemical plants, food plants, etc. |