ASTM B621-21

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it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation: B621 − 02 (Reapproved 2016) B621 − 21
Standard Specification for
Nickel-Iron-Chromium-Molybdenum Alloy (UNS N08320)
Rod
This standard is issued under the fixed designation B621; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope Scope*
2 3
1.1 This specification covers nickel-iron chromium-molybdenum alloy (UNS N08320) rod for use in general corrosive service.
1.2 The following products are covered under this specification:
5 3
1.2.1 Rods ⁄16 to ⁄4 in. (7.94 to 19.05 mm) excl in diameter, hot or cold finished, solution annealed and pickled or mechanically
descaled.
3 1
1.2.2 Rods ⁄4 to 3 ⁄2 in. (19.05 to 88.9 mm) incl in diameter, hot or cold finished, solution annealed, ground or turned.
1.3 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.
1.4 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 become familiar with all hazards including those identified in the appropriate Safety Data Sheet
(SDS) for this product/material as provided by the manufacturer, to establish appropriate safety safety, health, and healthenvi-
ronmental practices, and determine the applicability of regulatory limitations prior to use.
1.5 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.
2. Referenced Documents
2.1 ASTM Standards:
B880 Specification for General Requirements for Chemical Check Analysis Limits for Nickel, Nickel Alloys and Cobalt Alloys
B899 Terminology Relating to Non-ferrous Metals and Alloys
E8 Test Methods for Tension Testing of Metallic Materials [Metric] E0008_E0008M
E29 Practice for Using Significant Digits in Test Data to Determine Conformance with Specifications
E527 Practice for Numbering Metals and Alloys in the Unified Numbering System (UNS)
E1473 Test Methods for Chemical Analysis of Nickel, Cobalt and High-Temperature Alloys
This specification is under the jurisdiction of ASTM Committee B02 on Nonferrous Metals and Alloys and is the direct responsibility of Subcommittee B02.07 on Refined
Nickel and Cobalt and Their Alloys.
Current edition approved June 1, 2016Nov. 1, 2021. Published June 2016December 2021. Originally approved in 1977. Last previous edition approved in 20112016 as
B621 – 02 (2011).(2016). DOI: 10.1520/B0621-02R16.10.1520/B0621-21.
For ASME Boiler and Pressure Vessel Code applications see related Specification SB-621 in Section II of that Code.
New designation established in accordance with ASTM E527 and SAE J1086, Recommended Practice for Numbering Metals and Alloys (UNS).
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
*A Summary of Changes section appears at the end of this standard
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
B621 − 21
3. Terminology
3.1 The definitions in Terminology B899 are applicable to this specification.
3.2 Definitions of Terms Specific to This Standard:
3.2.1 rod, n—a product of round solid section furnished in straight lengths.
4. Ordering Information
4.1 It is the responsibility of the purchaser to specify all requirements that are necessary for material ordered under this
specification. Examples of such requirements include but are not limited to the following:
4.1.1 Dimensions—Nominal diameter and length. The shortest useable multiple length shall be specified (Table 1).
4.1.2 Certification—State if certification or a report of test results is required (Section 15).
4.1.3 Purchaser Inspection—State which tests or inspections are to be witnessed (Section 13).
4.1.4 Samples for Product (Check) Analysis—State whether samples shall be furnished (9.2.2).
5. Chemical Composition
5.1 The material shall conform to the composition limits specified in Table 2.
5.2 If a product (check) analysis is made by the purchaser, the material shall conform to the requirements specified in Table 2
subject to the permissible tolerances in Specification B880.
6. Mechanical Properties and Other Requirements
6.1 The mechanical properties of the material at room temperature shall conform to those shown in Table 3.
7. Dimensions, Mass and Permissible Variations
7.1 Diameter—The permissible variations from the specified diameter shall be as prescribed in Table 4.
TABLE 1 Permissible Variations in Length of Rods
Random mill lengths 2 to 12 ft (610 to 3660 mm) long
with not more than 25 weight % under
4 ft (1.22 m).
Multiple lengths Furnished in multiples of a
specified unit length, within the
length limits indicated above.
For each multiple, an allowance of ⁄4 in. (6.35
mm) shall be made for cutting, unless
otherwise specified. At the
manufacturer’s option, individual
specified unit lengths may be furnished.
Multiple lengths Furnished in multiples of a
specified unit length, within the
length limits indicated above.
For each multiple, an allowance of ⁄4 in.
(6.35 mm) shall be made for cutting, unless
otherwise specified. At the
manufacturer’s option, individual
specified unit lengths may be furnished.
Nominal lengths Specified nominal lengths having
a range of not less than 2 ft (610
mm) with no short lengths allowed.
Nominal lengths Specified nominal lengths having
a range of not less than 2 ft
(610 mm) with no short lengths allowed.
Cut lengths A specified length to which all
rods shall be cut with a permissible
variation of + ⁄8 in. (3.17 mm) - 0.
B621 − 21
TABLE 2 Chemical Requirements
Element Composition Limits,%
Nickel 25.0–27.0
A
Iron remainder
Chromium 21.0–23.0
Molybdenum 4.0–6.0
Manganese, max 2.5
Carbon, max 0.05
Titanium, min 4 × carbon
Silicon, max 1.00
Phosphorus, max 0.04
Sulfur, max 0.03
A
See 12.1.1.
TABLE 3 Mechanical Property Requirements
Tensile Strength, min, Yield Strength (0.2 % Elongation in 2 in.
A
psi (MPa) Offset), min, psi (MPa) (50.8) or 4D , min, %
75 000 (517) 28 000 (193) 35
A
D refers to the diameter of the tension specimen.
7.2 Out of Roundness—The permissible variation in roundness shall be as prescribed in Table 4.
7.3 Matching Allowances—When the surfaces of finished material are to be machined, the following allowances are suggested for
normal machining operations:
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7.3.1 As-finished (Annealed and Descaled)—For diameters of ⁄16 to ⁄16 in. (7.94 to 17.46 mm) incl, an allowance of ⁄
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