1.1 本规范 2. 涵盖用于焊接压力容器和管道部件的低碳时效硬化合金钢板。本规范涵盖镍铜铬钼铌（铌）钢。 1.2 本规范下的板材如下: 1.2.1 仅适用于A级3级。 1.2.1.1 淬火和沉淀热处理，较薄板材的最小规定抗拉强度为85 ksi，较厚板材的最小规定抗拉强度为75和70 ksi，最小抗拉强度取决于板材厚度。A级3级钢板的最大厚度仅受化学成分和热处理能力的限制，以满足规定的机械性能要求。 1.3 本规范以两英寸表示- 磅单位和国际单位制。但是，除非订单规定了适用的“M”规格名称（国际单位制），否则材料应以英寸-磅为单位提供。 1.4 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效值。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本规范。 1.5 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 2 covers low-carbon age-hardening alloy steel plates for welded pressure vessels and piping components. The specification covers nickel-copper-chromium-molybdenum-columbium (niobium) steel. 1.2 Plates under this specification are available as follows: 1.2.1 Available in Grade A, Class 3 only. 1.2.1.1 Quenched and precipitation heat treated with a minimum specified tensile strength of 85 ksi for thinner plates and 75 and 70 ksi for thicker plates, with the minimum tensile strength dependent upon the plate thickness. The maximum thickness of Grade A, Class 3 plates is limited only by the capacity of the chemical composition and heat treatment to meet the specified mechanical property requirements. 1.3 This specification is expressed in both inch-pound units and in SI units. However, unless the order specifies the applicable “M” specification designation (SI units), the material shall be furnished in inch-pound units. 1.4 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 this specification. 1.5 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.