1.1 本规范涵盖四个等级的锻造铌和铌合金棒材、棒材和线材，如下所示: 1.1.1 R04200类型1- 反应堆级非合金铌， 1.1.2 R04210类型2- 商业级非合金铌， 1.1.3 R04251类型3- 反应堆级铌合金，含1 % 锆，和 1.1.4 R04261类型4- 含1的商业级铌合金 % 锆。 1.2 以英寸-磅为单位的数值应视为标准值。括号中给出的值是到国际单位制的数学转换，仅供参考，不被视为标准值。 1.3 本标准并非旨在解决与其使用相关的所有安全问题（如有）。本标准的用户有责任在使用前制定适当的安全、健康和环境实践，并确定监管限制的适用性。 1.4 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。 ====意义和用途====== 13.1 为了确定是否符合本规范所列特性要求的规定限值，应按照实践中的舍入方法对观察值或计算值进行舍入 E29年 .

1.1 This specification covers four grades of wrought niobium and niobium alloy bar, rod, and wire as follows: 1.1.1 R04200-Type 1— Reactor grade unalloyed niobium, 1.1.2 R04210-Type 2— Commercial grade unalloyed niobium, 1.1.3 R04251-Type 3— Reactor grade niobium alloy containing 1 % zirconium, and 1.1.4 R04261-Type 4— Commercial grade niobium alloy containing 1 % zirconium. 1.2 The values stated in inch-pound units are to be regarded as standard. The values given in parentheses are mathematical conversions to SI units that are provided for information only and are not considered standard. 1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use. 1.4 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. ====== Significance And Use ====== 13.1 For the purposes of determining compliance with the specified limits for requirements of the properties listed in this specification, an observed value or a calculated value shall be rounded as indicated in accordance with the rounding method of Practice E29 .