ASTM B 393:2018

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.