ASTM B815-24

Standard Specification for Cobalt-Chromium-Nickel-Molybdenum-Tungsten Alloy<brk/> Bar or Rod

ABSTRACT
This specification covers cobalt-chromium-nickel-molybdenum-tungsten alloy (UNS R31233) in the form of a rod for wear applications and general corrosion service. The requirements for the chemical composition hardness and tolerance, tensile strength, yield strength, and elongation are specified.
SCOPE
1.1 This specification2 covers cobalt-chromium-nickel-molybdenum-tungsten alloy in the form of bar or rod. While the alloy is typically used for wear applications and general corrosion service, it is not limited to this usage.  
1.2 UNS R31233 is the only alloy currently allowed to be certified to this specification.  
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, health, and environmental 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.

General Information

• Status: Published
• Publication Date: 31-Mar-2024
• ICS: 77.150.70 - Cadmium and cobalt products
• Technical Committee: B02 - Nonferrous Metals and Alloys
• Drafting Committee: B02.07 - Refined Nickel and Cobalt and Their Alloys

Relations

• Replaces: ASTM B815-02(2016) - Standard Specification for Cobalt-Chromium-Nickel-Molybdenum-Tungsten Alloy<brk/> (UNS R31233) Rod
• Effective Date: 01-Apr-2024

Overview

ASTM B815-24: Standard Specification for Cobalt-Chromium-Nickel-Molybdenum-Tungsten Alloy Bar or Rod establishes requirements for UNS R31233 alloy products in the form of bars and rods. This standard, maintained by ASTM International, is specifically designed to support applications demanding high wear resistance and general corrosion protection. It outlines the necessary chemical composition, mechanical properties, dimensional tolerances, and quality assurance protocols for this multielement alloy, making it crucial for industries requiring reliable and durable nonferrous metal components.

Key Topics

• Materials and Composition
  ASTM B815-24 applies exclusively to the cobalt-chromium-nickel-molybdenum-tungsten alloy designated as UNS R31233. The standard mandates strict limits for elements such as chromium (23.5-27.5%), nickel (7.0-11.0%), molybdenum (4.0-6.0%), tungsten (1.0-3.0%), and others, with cobalt as the balance.

• Product Forms and Sizes

  • Bars and rods ranging from small to large diameters, manufactured via hot or cold finishing, solution annealed, and optionally ground, turned, or descaled.
  • Diameters and lengths must conform to prescribed tolerances, with specific guidance on permissible variations and straightness.

• Mechanical Properties
  To ensure product reliability, minimum mechanical properties include:

  • Tensile strength: 130 ksi (896 MPa)
  • Yield strength: 55 ksi (379 MPa)
  • Elongation: ≥15%

• Testing and Certification
  Each lot must be tested for chemical and mechanical properties using ASTM-specified methods (such as E8/E8M for tension testing and E1473 for chemical analysis). Certification and a report of test results are mandatory upon request.

• Marking and Identification
  All products must be clearly marked with the specification, alloy identification (UNS R31233), size, and manufacturer information, ensuring full traceability.

Applications

ASTM B815-24 alloy bars and rods are widely used in demanding industrial settings due to their excellent wear and corrosion resistance. Common applications include:

• Wear-resistant parts: Components exposed to abrasion, such as valve stems, pump shafts, and bushings.
• Corrosive environments: Process equipment in chemical, petrochemical, and marine industries where materials face aggressive media.
• High-temperature service: Environments requiring retention of strength and stability at elevated temperatures.
• General engineering: Applications where a combination of high mechanical strength and corrosion resistance is critical.

This standard ensures that manufacturers and end-users receive material with consistent quality, facilitating compliance in safety- and performance-critical sectors.

Related Standards

ASTM B815-24 references and complements several other ASTM standards and global codes, assisting users in broadening quality and compliance coverage:

• ASTM B880: General Requirements for Chemical Check Analysis Limits for Nickel, Nickel Alloys, and Cobalt Alloys
• ASTM B899: Terminology Relating to Nonferrous Metals and Alloys
• ASTM E8/E8M: Test Methods for Tension Testing of Metallic Materials
• ASTM E29: Practice for Using Significant Digits in Test Data
• ASTM E55: Practice for Sampling Wrought Nonferrous Metals and Alloys
• ASTM E1473: Test Methods for Chemical Analysis of Nickel, Cobalt, and High-Temperature Alloys
• ASME SB-815 (for pressure vessel code compliance)

Understanding ASTM B815-24 and its interrelationship with related standards is essential for purchasers, engineers, and quality professionals working with cobalt-based high-performance alloys. This ensures optimal material selection and regulatory conformity in advanced engineering applications.

Standards Content (Sample)

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.
Designation: B815 − 24
Standard Specification for
Cobalt-Chromium-Nickel-Molybdenum-Tungsten Alloy
Bar or Rod
This standard is issued under the fixed designation B815; 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* B899 Terminology Relating to Non-ferrous Metals and Al-
2 loys
1.1 This specification covers cobalt-chromium-nickel-
E8/E8M Test Methods for Tension Testing of Metallic Ma-
molybdenum-tungsten alloy in the form of bar or rod. While
terials
the alloy is typically used for wear applications and general
E29 Practice for Using Significant Digits in Test Data to
corrosion service, it is not limited to this usage.
Determine Conformance with Specifications
1.2 UNS R31233 is the only alloy currently allowed to be
E55 Practice for Sampling Wrought Nonferrous Metals and
certified to this specification.
Alloys for Determination of Chemical Composition
1.3 The values stated in inch-pound units are to be regarded E1473 Test Methods for Chemical Analysis of Nickel,
Cobalt, and High-Temperature Alloys
as standard. The values given in parentheses are mathematical
conversions to SI units that are provided for information only
and are not considered standard. 3. Terminology
1.4 This standard does not purport to address all of the
3.1 Common B02.07 terminology is found in Terminology
safety concerns, if any, associated with its use. It is the
B899.
responsibility of the user of this standard to become familiar
3.2 Definitions of Terms Specific to This Standard:
with all hazards including those identified in the appropriate
3.2.1 bar, n—an elongated, forged, or rolled metal product
Safety Data Sheet (SDS) for this product/material as provided
with uniform strength, length and diameter.
by the manufacturer, to establish appropriate safety, health,
3.2.2 rod, n—a hot-finished product of round solid section
and environmental practices, and determine the applicability
furnished in straight lengths.
of regulatory limitations prior to use.
1.5 This international standard was developed in accor-
4. Ordering Information
dance with internationally recognized principles on standard-
ization established in the Decision on Principles for the
4.1 It is the responsibility of the purchaser to specify all
Development of International Standards, Guides and Recom-
requirements that are necessary for material ordered under this
mendations issued by the World Trade Organization Technical
specification.
Barriers to Trade (TBT) Committee.
4.2 Examples of such requirements include, but are not
2. Referenced Documents limited to, the following:
3 4.2.1 Dimensions—Section 8.
2.1 ASTM Standards:
4.2.2 Purchaser Inspection—Section 13.
B880 Specification for General Requirements for Chemical
4.2.3 Samples for Product (Check) Analysis—Section 10.
Check Analysis Limits for Nickel, Nickel Alloys and
Cobalt Alloys
5. Materials and Manufacture
This specification is under the jurisdiction of ASTM Committee B02 on
5.1 The finish options for products certified to this specifi-
Nonferrous Metals and Alloys and is the direct responsibility of Subcommittee
cation are:
B02.07 on Refined Nickel and Cobalt and Their Alloys.
5.1.1 Hot-Finished, Annealed, and Descaled Rod.
Current edition approved April 1, 2024. Published April 2024. Originally
approved in 1991. Last previous edition approved in 2016 as B815 – 02 (2016). 5.1.2 Hot-Finished, Annealed, and Ground Bar.
DOI: 10.1520/B0815-24.
5.1.3 Hot-Finished, Annealed, and Turned Bar.
For ASME Boiler and Pressure Vessel Code applications, see related Specifi-
5.1.4 Cold-Finished and Annealed Bar.
cation SB-815 in Section II of that code.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or 5.1.5 Cold-Finished, Annealed, and Ground Bar.
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
5.2 The diameters permitted for certification for each finish
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. appear in the left column of Table 3.
*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
B815 − 24
A
TABLE 1 Chemical Requirements
8.5.2 Rods or bars ordered to cut lengths shall be furnished
Element Composition Limits, %
with square saw cut or machined ends.
Boron 0.015
8.6 Weight—For the purposes of calculating the weight of
Carbon 0.02 to 0.10
Chromium 23.5 to 27.5 the material covered by this specification, a density of
3 3
Iron 1.0 to 5.0
0.306 lb ⁄in. (8.48 g ⁄cm ) shall be used.
Manganese 0.1 to 1.5
Molybdenum 4.0 to 6.0
8.7 Straightness—The maximum curvature (depth of chord)
Nitrogen 0.03 to 0.12
shall not exceed the number calculated by the equation below.
Nickel 7.0 to 11.0
The calculated number is the maximum allowed curvature in
Phosphorous 0.030
Sulfur 0.020
inches (inch-pound units) or millimeters (SI units).
Silicon 0.05 to 1.00
Curvature customary unit 5 0.05 × length in feet
Tungsten 1.0 to 3.0 @ # ~ !
B
Cobalt Remainder
Curvature SI unit 5 0.04 × length in cm
@ # ~ !
A
Values in the table are maximums unless a range or minimum is indicated.
B
The composition of the remainder element shall be determined arithmetically by
9. Workmanship, Finish, and Appearance
difference.
9.1 The material shall be uniform in quality and condition.
9.2 The finish should be smooth and free of injurious
TABLE 2 Mechanical Property Requirements
defects.
Tensile Strength, min, ksi (MPa) 130 (896)
Yield Strength, min, ksi (MPa) 55 (379)
10. Sampling
A
Elongation in 2 in. (50.8 mm) or 4D , min, % 15
A
10.1 Lots for Chemical and Mechanical Testing:
D refers to the diameter of the tension specimen.
10.1.1 A lot for chemical analysis shall consist of one heat.
10.1.2 A lot for mechanical testing shall be defined as the
material from one heat in the same condition and specified
6. Chemical Composition
diameter.
6.1 The material shall conform to the chemical composition
10.2 Sampling for Chemical Analysis:
prescribed in Table 1.
10.2.1 A representative sample shall be obtained from each
6.2 If a product (check) analysis is made by the purchaser, heat during pouring or subsequent processing.
it shall be done in conformance with Specification B880. 10.2.2 Product (check) analysis shall be wholly the respon-
sibility of the purchaser. If the furnished sample is to be in
7. Mechanical Properties and Other Requirements
addition to the overall bulk product that was ordered, then this
shall be stipulated in the contract or purchase order.
7.1 The mechanical properties of the material at room
temperature shall conform to those given in Table 2.
10.3 Sampling for Mechanical Testing—A representative
sample shall be taken from each lot of finished material.
8. Dimensions, Mass, and Permissible Variations
11. Number of Tests and Retests
8.1 Diameter—The permissible variations from the speci-
fied diameter shall be as prescribed in Table 3.
11.1 Chemical Analysis—One test per heat.
8.2 Out-of-Roundness—The permissible variation in round-
11.2 Tension Tests—One test per lot.
ness shall be as prescribed in Table 3.
11.3 Retests—If the specimen used in the mechanical test of
8.3 Machining Allowances—When the surfaces of finished
any lot fails to meet the specified requirements, two additional
material are to be machined, the following allowances are
specimens shall be taken fro
...

This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Because
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: B815 − 02 (Reapproved 2016) B815 − 24
Standard Specification for
Cobalt-Chromium-Nickel-Molybdenum-Tungsten Alloy
(UNS R31233)Bar or Rod
This standard is issued under the fixed designation B815; 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*
1.1 This specification covers cobalt-chromium-nickel-molybdenum-tungsten alloy UNS R31233 in the form of rod bar or rod.
While the alloy is typically used for wear applications and general corrosion service.service, it is not limited to this usage.
1.2 The following products are covered under this specification:UNS R31233 is the only alloy currently allowed to be certified
to this specification.
3 3
1.2.1 Rods ⁄16 to ⁄4 in. (9.76 to 19.05 mm) exclusive in diameter, hot or cold finished, solution-annealed, and pickled or
mechanically descaled; and
3 1
1.2.2 Rods ⁄4 to 3 ⁄2 in. (19.05 to 88.9 mm) inclusive 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 and healthsafety, health, and
environmental 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
E8E8/E8M 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
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, 2016April 1, 2024. Published June 2016April 2024. Originally approved in 1991. Last previous edition approved in 20112016 as
B815 – 02 (2011).(2016). DOI: 10.1520/B0815-02R16.10.1520/B0815-24.
For ASME Boiler and Pressure Vessel Code applications, see related Specification SB-815 in Section II of that code.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at [e-mail]. 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
B815 − 24
E55 Practice for Sampling Wrought Nonferrous Metals and Alloys for Determination of Chemical Composition
E1473 Test Methods for Chemical Analysis of Nickel, Cobalt, and High-Temperature Alloys
3. Terminology
3.1 Common B02.07 terminology is found in Terminology B899.
3.2 Definitions of Terms Specific to This Standard:
3.2.1 bar, n—an elongated, forged, or rolled metal product with uniform strength, length and diameter.
3.2.2 rod, n—a hot-finished 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.
4.2 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 Alloy.
4.2.1 Dimensions—NominalSection 8diameter and length. The shortest usable multiple length shall be specified (.Table 1).
4.1.3 Certification—State whether certification or a report of test results is required (Section 15).
4.2.2 Purchaser Inspection—State which tests or inspections are to be witnessed (Section Section 13).
4.2.3 Samples for Product (Check) Analysis—State whether samples should be furnished (Section 9.2.210).
5. Materials and Manufacture
5.1 The finish options for products certified to this specification are:
5.1.1 Hot-Finished, Annealed, and Descaled Rod.
5.1.2 Hot-Finished, Annealed, and Ground Bar.
5.1.3 Hot-Finished, Annealed, and Turned Bar.
5.1.4 Cold-Finished and Annealed Bar.
5.1.5 Cold-Finished, Annealed, and Ground Bar.
5.2 The diameters permitted for certification for each finish appear in the left column of Table 3.
6. Chemical Composition
6.1 The material shall conform to the chemical composition requirements prescribed in Table 21.
6.2 If a product (check) analysis is made by the purchaser, the material shall conform to the requirements specified it shall be done
in Table 2 subject to the permissible tolerances given in conformance with Specification B880.
7. Mechanical Properties and Other Requirements
7.1 The mechanical properties of the material at room temperature shall conform to those given in Table 32.
B815 − 24
TABLE 2 Chemical Requirements
Element Composition Limits, %
Boron 0.015 max
Carbon 0.02–0.10
Chromium 23.5–27.5
Iron 1.0–5.0
Manganese 0.1–1.5
Molybdenum 4.0–6.0
Nitrogen 0.03–0.12
Nickel 7.0–11.0
Phosphorous 0.030 max
Sulfur 0.020 max
Silicon 0.05–1.00
Tungsten 1.0–3.0
A
Cobalt Remainder
A
TABLE 1 Chemical Requirements
Element Composition Limits, %
Boron 0.015
Carbon 0.02 to 0.10
Chromium 23.5 to 27.5
Iron 1.0 to 5.0
Manganese 0.1 to 1.5
Molybdenum 4.0 to 6.0
Nitrogen 0.03 to 0.12
Nickel 7.0 to 11.0
Phosphorous 0.030
Sulfur 0.020
Silicon 0.05 to 1.00
Tungsten 1.0 to 3.0
B
Cobalt Remainder
A
See Values 12.1.1.in the table are maximums unless a range or minimum is
indicated.
B
The composition of the remainder element shall be determined arithmetically by
difference.
TABLE 32 Mechanical Property Requirements
Tensile Strength, min, ksi (MPa) 130 (896)
Yield Strength, min, ksi (MPa) 55 (379)
A
Elongation in 2 in. (50.8 mm) or 4D , min, % 15
A
D refers to the diameter of the tension specimen.
8. Dimensions, Mass, and Permissible Variations
8.1 Diameter—The permissible variations from the specified diameter shall be as prescribed in Table 43.
8.2 Out-of-Roundness—The permissible variation in roundness shall be as prescribed in Table 43.
8.3 Machining Allowances—When the surfaces of finished material are to be machined, the following allowances are suggested
for normal machining operations:
5 11
8.3.1 As-Finished (Annealed and Descaled)—For diameters of ⁄16 in. to ⁄16 in. (7.94(7.94 mm to 17.46 mm) inclusive, an
allowance of ⁄16 in. (1.59 mm) should be added on the diameter should be made for finish machining.
8.4 Length:
8.4.1 Unless multiple, nominal, or cut lengths are specified, random mill lengths shall be furnished.
8.4.2 The permissible variations in length of multiple, nominal, or cut length rod shall be as prescribed in Table 14. Where rods
are ordered in multiple lengths, a ⁄4-in. (6.35-mm) in. (6.35 mm) length addition shall be permitted for each uncut multiple length.
8.5 Ends:
B815 − 24
TABLE 4 Permissible Variations in Diameter and Out-of-Roundness of Finished Rods
Permissible Variations, in. (mm)
Specified Diameter, in. (mm) Diameter
Out-of-Roundness, max
+ −
Hot-Finished, Annealed, and Descaled Rods
3 7
⁄16 to ⁄16 (4.76–11.11), incl 0.012 (0.30) 0.012 (0.30) 0.018 (0.46)
7 5
Over ⁄16 to ⁄8 (11.11–15.87), incl 0.014 (0.36) 0.014 (0.36) 0.020 (0.51)
5 3
Over ⁄8 to ⁄4 (15.87–19.05), excl 0.016 (0.41) 0.016 (0.41) 0.024 (0.61)
Hot-Finished, Annealed, and Ground or Turned Rods
5 5
⁄16 to 3 ⁄8 (19.05–88.9), incl 0.010 (0.25) 0 0.008 (0.20)
TABLE 3 Permissible Variations in Diameter and Out-of-Roundness of Finished Products
Permissible Variations, in. (mm)
Specified Diameter, in. (mm) Diameter
Out-of-Roundness, max
+ −
Hot-Finished, Annealed, and Descaled Rod
3 7
⁄16 to ⁄16 (4.76 to 11.11), incl 0.012 (0.30) 0.012 (0.30) 0.018 (0.46)
7 5
Over ⁄16 to ⁄8 (11.11 to 15.87), incl 0.014 (0.36) 0.014 (0.36) 0.020 (0.51)
Over ⁄8 to 1 (15.87 to 25.4), incl 0.016 (0.41) 0.016 (0.41) 0.024 (0.61)
Over 1.0 to 2.0 (25.4 to 50.8), incl 0.031 (0.79) 0.016 (0.41) 0.035 (0.89)
Over 2.0 to 3 ⁄8 (50.8 to 92.08), 0.047 (1.19) 0.031 (0.79) 0.058 (1.47)
excl
Hot-Finished, Annealed, and Ground Bar
5 5
⁄16 to 3 ⁄8 (50.8 to 92.08), incl 0.010 (0.25) 0 0.008 (0.20)
Over 3 ⁄8 to 6.0 (92.08 to 152.4), 0.050 (1.27) 0 ---
incl
Hot-Finished, Annealed, and Turned Bar
3 ⁄8 to 6.0 (92.08 to 152.4) 0.125 (3.18) 0 ---
Cold-Finished, Annealed Bar
1 3
⁄8 to ⁄4 (3.18 to 19.05) 0.010 (0.25) 0 0.008 (0.20)
Cold-Finished, Annealed, and Ground Bar
1 3
⁄8 to ⁄4 (3.18 to 19.05) 0.002 (0.05) 0.002 (0.05) 0.002 (0.05)
8.5.1 Rods or bars ordered to random or nominal lengths shall be furnished with either cropped or sawed ends.
8.5.2 Rods or bars ordered to cut lengths shall be furnished with square saw cut or machined ends.
8.6 Weight—
...