1.1 本规范 2. 涵盖主要用于焊接压力容器的碳钢板，其中改善缺口韧性很重要。 1.2 本规范下的板材有四个等级，具有以下不同的强度等级: 美国等级[SI] 抗拉强度， ksi[MPa] 55 [380] 55–75 [380–515] 60 [415] 60–80 [415–550] 65 [450] 65–85 [450–585] 70 [485] 70–90 [485–620] 1.3 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。 1.4 对于由线圈生产且未经热处理或仅进行应力消除的板材，附加要求，包括附加测试要求和规范附加测试结果的报告 A20/A20M 申请 1.5 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。 1.6 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 carbon steel plates intended primarily for service in welded pressure vessels where improved notch toughness is important. 1.2 Plates under this specification are available in four grades having different strength levels as follows: Grade U.S. [SI] Tensile Strength, ksi [MPa] 55 [380] 55–75 [380–515] 60 [415] 60–80 [415–550] 65 [450] 65–85 [450–585] 70 [485] 70–90 [485–620] 1.3 The maximum thickness of plates is limited only by the capacity of the composition to meet the specified mechanical property requirements. 1.4 For plates produced from coil and furnished without heat treatment or with stress relieving only, the additional requirements, including additional testing requirements and the reporting of additional test results of Specification A20/A20M apply. 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 the 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.