Alloy 28 stainless steel tubes are delivered in a fully heat-treated condition. For additional processing, the following heat treatment is recommended to maintain optimal corrosion resistance and mechanical properties.
For Alloy 28, solution annealing is performed at 1100–1160°C (2010–2120°F) for 10–30 minutes, followed by quenching in water. Thin-walled tubes can also be cooled rapidly in air to prevent distortion.
Alloy 28 is a high-alloy austenitic stainless steel designed for service in highly corrosive conditions. Key characteristics include:
| Material | C (Max %) | Cr (%) | Ni (%) | Mo (%) | Cu (%) | W (%) | Co (%) | Others |
| Alloy 28 | 0.02 | 27 | 31 | 3.5 | 1.0 | - | - | - |
| Alloy 904L | 0.02 | 20 | 25 | 4.5 | 1.5 | - | - | - |
| UNS N08020 | 0.07 | 20 | 34 | 2.5 | 3.3 | - | - | Nb |
| Alloy 825 | 0.05 | 21.5 | 42 | 3 | 2.3 | - | - | Ti |
| Alloy G | 0.03 | 22 | 45 | 6.5 | 2 | 1.0 | 2.5 | Nb |
| Alloy C | 0.08 | 15.5 | 54 | 16 | - | 4 | 2.5 | - |
| UNS Number | N08028 |
| ISO Number | 4563-080-28-I |
| EN Number / Name | 1.4563 / X1NiCrMoCu 31-27-4 |
| W.Nr. | 1.4563 |
| Product Standards | ASTM B668, EN 10216-5, ASTM B709, EN 10088-2, ASTM A403 |
| Approvals | ASME Section I, III, VIII, NACE MR0103, NACE MR0175/ISO 15156 |
Alloy 28 is widely used in industries requiring high corrosion resistance, including:
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