This specification covers austenitic-ferritic (duplex) stainless steel castings for valves, flanges, fittings, and other pressure-containing parts. The duplex stainless steels offer a combination of enhanced mechanical properties and corrosion resistance when properly balanced in composition and properly heat treated. Ferrite levels are not specified, but these grades will develop a range of approximately 30 to 60 % ferrite with the balance austenite. It is the responsibility of the purchaser to determine which grade shall be furnished depending on design and service conditions, mechanical properties, and corrosionresistant characteristics.
| Type | Grade | UNS |
|---|---|---|
| 25Cr - 5Ni - M0 - Cu - N | 1BA | J93372 |
| 25Cr - 6Ni - Mo - Cu - N | 1CB | J93373 |
| 24Cr - 10Ni - Mo - N | 2A | J93345 |
| 25Cr - 5Ni - Mo - N | 3A | J93371 |
| 22Cr - 5Ni - Mo - N | 4A | J92205 |
| 25Cr - 7Ni - Mo - N | 5AB | J93404 |
| 25Cr - 7Ni - Mo - N | 6AB | J93380 |
| 27Cr - 7Ni - Mo - W - N | 7AC | J93379 |