1.1 本规范涵盖一般应用的低碳沉淀强化镍-铜-铬-钼-铌（铌）合金钢板。本规范中的合金在不同温度范围内通过沉淀强化。在热轧后的空气冷却、正火期间以及通过另一次热处理，可以发生沉淀强化。这些等级不适用于高于900°F[480°C]的应用。 1.2 提供两个等级，每个等级有三个等级，如下所示: 等级和等级 条件 A级，1级 轧制和沉淀热处理 A级，2级 正火和沉淀热处理 A级，3级 淬火和沉淀热处理 B级，1级 轧制时 B级，2级 归一化 B级，3级 正火和沉淀热处理 1.3 A级提供的最小屈服强度水平范围为50至85 ksi[345至585 MPa]，具体取决于厚度和条件。 1.4 A级1级钢板的最大厚度为 3. / 4. 在里面[20毫米]。A级2级和3级的最大厚度仅受满足规定机械性能要求的成分能力的限制；然而，目前的做法通常将最大厚度限制为8英寸。[200毫米]。 1.5 规定了A级1级的强制性缺口韧性要求。 1.6 根据厚度和条件，B级提供70至75 ksi[485至515 MPa]的最小屈服强度水平。 1.7 B级板的最大厚度限制为2英寸。[50毫米]。 1.8 规定了三类B级材料的强制性缺口韧性要求。 1.9 在焊接钢材时，先决条件是采用适合钢材等级和预期用途或服务的焊接工艺。见规范附录X3 A6/A6M 有关焊接性的信息。 1.10 以英寸-磅单位或国际单位表示的数值应单独视为标准值。在文本中，国际单位显示在括号中。每个系统中规定的值不是精确的等价物；因此，每个系统必须相互独立使用。合并两个系统的值可能会导致不符合规范。 1.11 本国际标准是根据世界贸易组织技术性贸易壁垒（TBT）委员会发布的《关于制定国际标准、指南和建议的原则的决定》中确立的国际公认标准化原则制定的。

1.1 This specification covers low-carbon precipitation — strengthened nickel - copper - chromium - molybdenum - columbium (niobium) 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 [480°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 [485 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. 1.9 When the steel is to be welded, it is presupposed that a welding procedure suitable for the grade of steel and intended use or service will be utilized. See Appendix X3 of Specification A6/A6M for information on weldability. 1.10 The values stated in either inch-pound units or SI units are to be regarded separately as standard. Within the text, the SI units are shown in brackets. The values stated in each system are not exact equivalents; therefore, each system must be used independently of the other. Combining values from the two systems may result in nonconformance with the specification. 1.11 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.