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.

This specification covers five grades of wrought niobium and niobium alloy strip, sheet, and plate. These are reactor grade unalloyed niobium (R04200-Type 1), commercial grade unalloyed niobium (R04210-Type 2), reactor grade niobium alloy containing 1% zirconium (R04251-Type 3), commercial grade niobium alloy containing 1% zirconium (R04261-Type 4), and RRR grade pure niobium (R0xxxx-Type 5). The RRR grade pure niobium is used in superconducting applications that require ultra high purity, making it conducive to very large grains that can adversely affect formability. It is therefore not recommended for other applications. The materials shall be made from ingots produced by vacuum or plasma arc welding, vacuum electron-beam melting, or a combination of these three methods. The various niobium mill products covered by this specification are formed with the conventional extrusion, forging, swaging, rolling, and drawing equipment normally available in metal working plants. Samples for chemical and tension testing shall be taken from the finished material after the metallurgical processing to determine conformity to this specification. The samples may be taken prior to final inspection and minor surface conditioning by abrasion and pickling shall be representative of the finished product.

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, and

1.1.4 R04261-Type 4—Commercial grade niobium alloy containing 1 % zirconium.

1.1.5 R0xxxx-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.

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 and health practices and determine the applicability of regulatory limitations prior to use.