1.1 本规范 2. 涵盖铬钼合金钢板，主要用于设计用于高温服务的焊接锅炉和压力容器。 1.2 根据本规范，可提供几种不同合金含量的板材，如下所示: 名义上的 名义上的 铬 钼 等级 所容纳之物 % 所容纳之物 % 2. 0.50 0.50 12 1 0.50 11 1.25 0.50 22 2.25 1 21 3 1 5. 5 0.50 9 9 1 91 9 1 1.3 除91级外，每个等级都有两类抗拉强度等级，如抗拉要求表中所定义。91级只能作为2级。91级由两种类型组成，其中2型与1型的区别在于需要有限的成分来增强抗蠕变性能。 注1: 本规范先前涵盖的911级现在包含在本规范中 2017年/2017年 。 1.4 板材的最大厚度仅受成分满足规定机械性能要求的能力的限制。 1.5 以英寸磅单位或国际单位制表示的数值应单独视为标准。在正文中，国际单位制显示在括号中。每个系统中规定的值并不完全相等。因此，每个系统必须独立使用。将两个系统的值组合在一起可能会导致不符合本规范。 1.6 本国际标准是根据世界贸易组织技术性贸易壁垒委员会发布的《关于制定国际标准、指南和建议的原则的决定》中确立的国际公认的标准化原则制定的。

1.1 This specification 2 covers chromium-molybdenum alloy steel plates intended primarily for welded boilers and pressure vessels designed for elevated temperature service. 1.2 Plates are available under this specification in several grades having different alloy contents as follows: Nominal Nominal Chromium Molybdenum Grade Content, % Content, % 2 0.50 0.50 12 1.00 0.50 11 1.25 0.50 22 2.25 1.00 21 3.00 1.00 5 5.00 0.50 9 9.00 1.00 91 9.00 1.00 1.3 Each grade except Grade 91 is available in two classes of tensile strength levels as defined in the Tensile Requirements tables. Grade 91 is available only as Class 2. Grade 91 consists of two types, with Type 2 differentiated from Type 1 by requiring restricted composition for the enhancement of creep resistance. Note 1: Grade 911, previously covered by this specification, is now covered by Specification A1017/A1017M . 1.4 The maximum thickness of plates is limited only by the capacity of the composition to meet the specified mechanical property requirements. 1.5 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. 1.6 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.