1.1 本规范涵盖五个等级的锻造铌和铌合金带材、薄板和板材，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， 1.1.4 R04261类型4- 含1的商业级铌合金 % 锆，和。 1.1.5 R04220 5型- RRR级纯铌。 注1: 这种级别的铌用于需要超高纯度的超导应用。由于产品纯度高，因此有利于形成可能对成形性产生不利影响的大晶粒。 不建议将其用于其他应用。 1.2 尺寸公差除外 表1 ，以英寸-磅单位表示的值应视为标准值。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。 （A） 板材厚度公差超过24英寸。（610 mm）宽应为±10 % 的厚度。 （B） 剪切板材的宽度公差应为± 1. / 16 在里面（±1.6 mm），剪切板上应为± 1. / 8. 在里面（±3.2 mm），材料厚度不超过0.375 in。（9.5毫米）。 1.3 以下预防性警告仅适用于本规范的测试方法部分 . 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 five grades of wrought niobium and niobium alloy strip, sheet, and plate 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, 1.1.4 R04261-Type 4— Commercial grade niobium alloy containing 1 % zirconium, and. 1.1.5 R04220-Type 5— RRR grade pure niobium. Note 1: This grade of niobium is used in superconducting applications that require the ultra high purity. Because of the high purity the product is conducive to very large grains that can adversely affect formability. It is not recommended for other applications. 1.2 Except for dimensional tolerances in Table 1 , 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. (A) Tolerance on thickness of sheet over 24 in. (610 mm) wide shall be ±10 % of the thickness. (B) Tolerance on width of sheared sheet shall be ± 1 / 16 in. (±1.6 mm) and on sheared plate shall be ± 1 / 8 in. (±3.2 mm) up to material thickness of 0.375 in. (9.5 mm). 1.3 The following precautionary caveat pertains only to the test methods portion of this specification . 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 .