1.1 This specification covers low-carbon precipitation—strengthened nickel - copper - chromium - molybdenum - columbium alloy steel plates for general applications. The alloys in this specification are strengthened by precipitation in various temperature ranges. Precipitation strengthening can occur upon air cooling after hot rolling, during normalizing, and by another heat treatment. These grades are not intended for use in applications above 900°F [540°C].
1.2 Two grades, each with three classes, are provided as follows:
| Grade and Class | Condition |
| Grade A, Class 1 | as-rolled and precipitation heat treated |
| Grade A, Class 2 | normalized and precipitation heat treated |
| Grade A, Class 3 | quenched and precipitation heat treated |
| Grade B, Class 1 | as-rolled |
| Grade B, Class 2 | normalized |
| Grade B, Class 3 | normalized and precipitation heat treated |
1.3 Grade A provides minimum yield strength levels ranging from 50 to 85 ksi [345 to 585 MPa], depending on thickness and condition.
1.4 Grade A, Class 1, plates are limited to a maximum thickness of 3/4 in. [20 mm]. The maximum thickness of Grade A, Classes 2 and 3, is limited only by the capacity of the composition to meet the specified mechanical property requirements; however, current practice normally limits the maximum thickness to 8 in. [200 mm].
1.5 Mandatory notch toughness requirements are specified for Grade A, Class 1.
1.6 Grade B provides minimum yield strength levels ranging from 70 to 75 ksi [480 to 515 MPa], depending on thickness and condition.
1.7 Grade B plates are limited to a maximum thickness of 2 in. [50 mm].
1.8 Mandatory notch toughness requirements are specified for the three classes of Grade B.