ASTM F961-20

Standard Specification for 35Cobalt-35Nickel-20Chromium-10Molybdenum Alloy Forgings for Surgical Implants (UNS R30035)

ABSTRACT
This specification covers the chemical composition and mechanical requirements for 35cobalt-35nickel-20chromium-10molybdenum alloy (UNS R30035) forgings for use in surgical implants. The material covered here shall be in the form of bars, plates, sheets, or wires manufactured in the solution-annealed condition with a finish suitable for forging by hammering, pressing, rolling, extruding, or upsetting.
SCOPE
1.1 This specification covers the chemical, mechanical, and metallurgical requirements for 35cobalt-35nickel-20chromium-10molybdenum alloy (UNS R30035) in the form of forgings, used for the manufacture of surgical implants.  
1.2 Units—The values stated in either SI units or inch-pound units are to be regarded separately as standard. The values stated in each system are not necessarily exact equivalents; therefore, to ensure conformance with the standard, each system shall be used independently of the other, and values from the two systems shall not be combined.  
1.3 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.

General Information

• Status: Published
• Publication Date: 31-Jan-2020
• ICS: 11.040.40 - Implants for surgery, prosthetics and orthotics
• Technical Committee: F04 - Medical and Surgical Materials and Devices
• Drafting Committee: F04.12 - Metallurgical Materials

Relations

• Replaces: ASTM F961-14 - Standard Specification for 35Cobalt-35Nickel-20Chromium-10Molybdenum Alloy Forgings for Surgical Implants (UNS R30035)
• Effective Date: 01-Feb-2020
• Refers: ASTM A484/A484M-24 - Standard Specification for General Requirements for Stainless Steel Bars, Billets, Shapes, and Forgings
• Effective Date: 01-Jan-2024
• Refers: ASTM E8/E8M-24 - Standard Test Methods for Tension Testing of Metallic Materials
• Effective Date: 01-Jan-2024
• Refers: ASTM A484/A484M-23a - Standard Specification for General Requirements for Stainless Steel Bars, Billets, Shapes, and Forgings
• Effective Date: 01-Sep-2023
• Refers: ASTM A484/A484M-23 - Standard Specification for General Requirements for Stainless Steel Bars, Billets, and Forgings
• Effective Date: 01-Mar-2023
• Refers: ASTM A484/A484M-20a - Standard Specification for General Requirements for Stainless Steel Bars, Billets, and Forgings
• Effective Date: 05-May-2020
• Refers: ASTM A484/A484M-19 - Standard Specification for General Requirements for Stainless Steel Bars, Billets, and Forgings
• Effective Date: 01-Sep-2019
• Refers: ASTM F688-19 - Standard Specification for Wrought Cobalt-35Nickel-20Chromium-10Molybdenum Alloy Plate, Sheet, and Foil for Surgical Implants (UNS R30035)
• Effective Date: 01-Feb-2019
• Refers: ASTM A484/A484M-18a - Standard Specification for General Requirements for Stainless Steel Bars, Billets, and Forgings
• Effective Date: 01-Nov-2018
• Refers: ASTM E18-18 - Standard Test Methods for Rockwell Hardness of Metallic Materials
• Effective Date: 01-Jul-2018
• Refers: ASTM A484/A484M-18 - Standard Specification for General Requirements for Stainless Steel Bars, Billets, and Forgings
• Effective Date: 01-Jan-2018
• Refers: ASTM E18-17 - Standard Test Methods for Rockwell Hardness of Metallic Materials
• Effective Date: 01-Jul-2017
• Refers: ASTM E8/E8M-16 - Standard Test Methods for Tension Testing of Metallic Materials
• Effective Date: 15-Jul-2016
• Refers: ASTM A484/A484M-16 - Standard Specification for General Requirements for Stainless Steel Bars, Billets, and Forgings
• Effective Date: 01-Jan-2016
• Refers: ASTM A555/A555M-16 - Standard Specification for General Requirements for Stainless Steel Wire and Wire Rods
• Effective Date: 01-Jan-2016

Overview

ASTM F961-20 is the internationally recognized standard specification for 35Cobalt-35Nickel-20Chromium-10Molybdenum alloy forgings (UNS R30035) used in the manufacture of surgical implants. Developed by ASTM International, this standard outlines the chemical, mechanical, and metallurgical requirements for forgings made from this high-performance alloy. The specification encompasses materials in the form of bars, plates, sheets, or wires, processed under controlled conditions to ensure their suitability for medical implant applications.

This standard supports quality assurance, regulatory compliance, and consistency in the fabrication of medical devices, helping manufacturers meet patient safety and product reliability requirements worldwide.

Key Topics

• Material Forms and Processing

  • The standard covers forgings produced from bars or wires in a solution-annealed state.
  • Acceptable processing methods include hammering, pressing, rolling, extruding, or upsetting to achieve desired shapes for surgical implants.

• Chemical and Mechanical Requirements

  • Specifies product analysis limits for chemical composition to ensure material consistency.
  • Mandates minimum mechanical properties, including tensile strength and hardness, using referenced ASTM test methods.
  • Mechanical testing is required for each production lot to ensure uniformity and compliance.

• Metallurgical Quality

  • Defines requirements for material integrity, including the absence of splits, cracks, and other flaws.
  • Completion of all hot-working operations is followed by a controlled annealing treatment to optimize material properties.
  • Grain size is tested and agreed upon by purchaser and supplier for optimal performance in surgical applications.

• Units and Certification

  • Permits use of either SI or inch-pound units, but prohibits mixing to prevent nonconformance.
  • Suppliers must provide certification and test reports confirming compliance.
  • Requires a documented quality program conforming to ISO 9001, ISO 13485, or equivalent.

• Biocompatibility

  • The specified alloy is well documented for biocompatibility, with decades of successful clinical use in contact with bone and soft tissue.

Applications

• Orthopedic Implants: Suitable for manufacturing hip and knee joint components, as well as trauma fixation hardware.
• Dental Implants: Used in abutments and frameworks requiring high strength and corrosion resistance.
• Spinal Devices: Ideal for rods, plates, and screws due to its excellent fatigue properties and tissue compatibility.
• General Surgical Implants: Supports fabrication of cardiovascular, neurological, and other implantable medical devices.

The combination of high strength, corrosion resistance, and proven biocompatibility makes the 35Co-35Ni-20Cr-10Mo alloy (UNS R30035) a preferred choice in advanced surgical implant applications globally.

Related Standards

• ASTM F562: Specification for wrought 35Cobalt-35Nickel-20Chromium-10Molybdenum alloy for surgical implant applications.
• ASTM F688: Specification for plate, sheet, and foil made from the same alloy for surgical implants.
• ASTM A484/A484M: General requirements for stainless steel bars, billets, and forgings.
• ASTM A751, E8/E8M, E10, E18, E112: Various test methods for chemical analysis, tensile testing, hardness, and grain size.
• ISO 5832-6: International standard for wrought cobalt-nickel-chromium-molybdenum alloys for surgical implants.
• ISO 9001, ISO 13485: Quality management system requirements for general industry and medical devices.

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Manufacturers, medical device designers, and regulatory bodies rely on ASTM F961-20 for ensuring the reliability, safety, and regulatory compliance of surgical implants produced from UNS R30035 forgings. Adhering to this standard helps promote best practices in medical device manufacturing and enhances patient safety.

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: F961 −20
Standard Specification for
35Cobalt-35Nickel-20Chromium-10Molybdenum Alloy
Forgings for Surgical Implants (UNS R30035)
ThisstandardisissuedunderthefixeddesignationF961;thenumberimmediatelyfollowingthedesignationindicatestheyearoforiginal
adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.Asuperscript
epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope* E10 Test Method for Brinell Hardness of Metallic Materials
E18 Test Methods for Rockwell Hardness of Metallic Ma-
1.1 This specification covers the chemical, mechanical, and
terials
metallurgical requirements for 35cobalt-35nickel-
E29 Practice for Using Significant Digits in Test Data to
20chromium-10molybdenum alloy (UNS R30035) in the form
Determine Conformance with Specifications
of forgings, used for the manufacture of surgical implants.
E92 Test Methods for Vickers Hardness and Knoop Hard-
1.2 Units—The values stated in either SI units or inch-
ness of Metallic Materials
pound units are to be regarded separately as standard. The
E112 Test Methods for Determining Average Grain Size
values stated in each system are not necessarily exact equiva-
E140 Hardness Conversion Tables for Metals Relationship
lents; therefore, to ensure conformance with the standard, each
Among Brinell Hardness, Vickers Hardness, Rockwell
system shall be used independently of the other, and values
Hardness, Superficial Hardness, Knoop Hardness, Sclero-
from the two systems shall not be combined.
scope Hardness, and Leeb Hardness
1.3 This standard does not purport to address all of the
E165 Practice for Liquid Penetrant Testing for General
safety concerns, if any, associated with its use. It is the Industry
responsibility of the user of this standard to establish appro-
E354 Test Methods for Chemical Analysis of High-
priate safety, health, and environmental practices and deter- Temperature,Electrical,Magnetic,andOtherSimilarIron,
mine the applicability of regulatory limitations prior to use.
Nickel, and Cobalt Alloys
1.4 This international standard was developed in accor- F562 Specification for Wrought 35Cobalt-35Nickel-
dance with internationally recognized principles on standard-
20Chromium-10Molybdenum Alloy for Surgical Implant
ization established in the Decision on Principles for the Applications (UNS R30035)
Development of International Standards, Guides and Recom-
F601 Practice for Fluorescent Penetrant Inspection of Me-
mendations issued by the World Trade Organization Technical
tallic Surgical Implants
Barriers to Trade (TBT) Committee. F688 Specification for Wrought Cobalt-35Nickel-
20Chromium-10MolybdenumAlloy Plate, Sheet, and Foil
2. Referenced Documents
for Surgical Implants (UNS R30035)
2.1 ASTM Standards:
IEEE/ASTM SI 10 American National Standard for Use of
A484/A484M Specification for General Requirements for
theInternationalSystemofUnits(SI):TheModernMetric
Stainless Steel Bars, Billets, and Forgings
System
A555/A555M Specification for General Requirements for
2.2 ISO Standards:
Stainless Steel Wire and Wire Rods
ISO 5832-6 Implants for Surgery–Metallic Materials–Part 6:
A751 Test Methods, Practices, and Terminology for Chemi-
Wrought Cobalt-Nickel-Chromium-Molybdenum Alloy
cal Analysis of Steel Products
ISO 9001 Quality Management Systems—Requirements
E8/E8M Test Methods for Tension Testing of Metallic Ma-
ISO 13485 Medical Devices—Quality Management
terials
Systems—Requirements for Regulatory Purposes
3. Terminology
This specification is under the jurisdiction of ASTM Committee F04 on
Medical and Surgical Materials and Devices and is the direct responsibility of
3.1 Definitions of Terms Specific to This Standard:
Subcommittee F04.12 on Metallurgical Materials
3.1.1 lot, n—the total number of forgings produced from the
Current edition approved Feb. 1, 2020. Published April 2020. Originally
approved in 1985. Last previous edition approved in 2014 as F961 – 14. DOI: same heat under the same conditions at essentially the same
10.1520/F0961-20.
time.
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 Available fromAmerican National Standards Institute (ANSI), 25 W. 43rd St.,
the ASTM website. 4th Floor, New York, NY 10036, http://www.ansi.org.
*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
F961 − 20
4. Ordering Information 7. Mechanical Requirements
4.1 Inquiries and orders for forgings under this specification 7.1 Tensile Properties:
shall include the following information: 7.1.1 The mechanical properties of forgings shall be tested
4.1.1 Quantity; by the forger and shall comply with the minimum mechanical
4.1.2 ASTM designation and date of issue; properties as specified in Specification F562.
4.1.3 Mechanical properties (if applicable, for special con- 7.1.2 Test specimens shall be taken from a representative
ditions); forging if possible, or from a representative forged test bar. A
4.1.4 Form (bar or wire); representative forged test bar may only be used if the configu-
4.1.5 Applicable dimensions, including size, thickness, ration is such that a test bar cannot be obtained.Any specially
width, and length (exact, random, or multiples), or drawing forgedtestbarmustbeannealedwiththeforgingsitrepresents.
number; 7.1.3 Specimens for tension tests shall be machined and
4.1.6 Tolerances—Unless otherwise specified by purchaser, tested in accordance with Test Methods E8/E8M.
tolerances must meet the requirements of Specification A484/
7.2 Number of Tests:
A484M, Specification A555/A555M, or both, as applicable;
7.2.1 Perform at least one tension test from each lot in the
4.1.7 Condition (see 5.1);
longitudinal direction. Should this test result not meet the
4.1.8 Finish;
specifiedrequirements,testtwoadditionaltestpiecesrepresen-
4.1.9 Special tests (if any); and
tative of the same lot, in the same manner, for each failed test
4.1.10 Other requirements.
piece. The lot shall be considered in compliance only if both
additional test pieces meet the specified requirements.
5. Materials and Manufacture
7.2.2 Tensile test results for which any specimen fractures
5.1 Condition:
outside the gauge length shall be considered acceptable if both
5.1.1 Materialforforgingsshallbebarsorwirefabricatedin
the elongation and reduction of area meet the minimum
accordance with Specification F562 or Specification F688.The
requirements specified. Refer to sections 7.11.4 and 7.11.5 of
material shall be generally in the solution-annealed condition
Test Methods E8/E8M. If either the elongation or reduction of
with a finish suitable for forging.
area is less than the minimum requirement, discard the test and
5.1.2 The material shall be forged by hammering, pressing,
retest.Retestonespecimenforeachspecimenthatdidnotmeet
extruding,orupsettingandshallbeprocessed,ifpracticable,so
the minimum requirements.
as to cause metal flow during the hot working operation in the
7.3 Hardness:
dir
...

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: F961 − 14 F961 − 20
Standard Specification for
35Cobalt-35Nickel-20Chromium-10Molybdenum Alloy
Forgings for Surgical Implants (UNS R30035)
This standard is issued under the fixed designation F961; 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*
1.1 This specification covers the chemical, mechanical, and metallurgical requirements for 35cobalt-35nickel-20chromium-
10molybdenum alloy (UNS R30035) in the form of forgings, used for the manufacture of surgical implants.
1.2 Units—The values stated in either SI units or inch-pound units are to be regarded separately as standard. The values stated
in each system mayare not benecessarily exact equivalents; therefore, to ensure conformance with the standard, each system shall
be used independently of the other. Combiningother, and values from the two systems may result in nonconformance with the
standard.shall not be combined.
1.3 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.
2. Referenced Documents
2.1 ASTM Standards:
A484/A484M Specification for General Requirements for Stainless Steel Bars, Billets, and Forgings
A555/A555M Specification for General Requirements for Stainless Steel Wire and Wire Rods
A751 Test Methods, Practices, and Terminology for Chemical Analysis of Steel Products
E8/E8M Test Methods for Tension Testing of Metallic Materials
E10 Test Method for Brinell Hardness of Metallic Materials
E18 Test Methods for Rockwell Hardness of Metallic Materials
E29 Practice for Using Significant Digits in Test Data to Determine Conformance with Specifications
E92 Test Methods for Vickers Hardness and Knoop Hardness of Metallic Materials
E112 Test Methods for Determining Average Grain Size
E140 Hardness Conversion Tables for Metals Relationship Among Brinell Hardness, Vickers Hardness, Rockwell Hardness,
Superficial Hardness, Knoop Hardness, Scleroscope Hardness, and Leeb Hardness
E165 Practice for Liquid Penetrant Testing for General Industry
E354 Test Methods for Chemical Analysis of High-Temperature, Electrical, Magnetic, and Other Similar Iron, Nickel, and
Cobalt Alloys
F562 Specification for Wrought 35Cobalt-35Nickel-20Chromium-10Molybdenum Alloy for Surgical Implant Applications
(UNS R30035)
F601 Practice for Fluorescent Penetrant Inspection of Metallic Surgical Implants
F688 Specification for Wrought Cobalt-35Nickel-20Chromium-10Molybdenum Alloy Plate, Sheet, and Foil for Surgical
Implants (UNS R30035)
This specification is under the jurisdiction of ASTM Committee F04 on Medical and Surgical Materials and Devices and is the direct responsibility of Subcommittee
F04.12 on Metallurgical Materials
Current edition approved Oct. 1, 2014Feb. 1, 2020. Published November 2014April 2020. Originally approved in 1985. Last previous edition approved in 20082014 as
F961 – 08.F961 – 14. DOI: 10.1520/F0961-14.10.1520/F0961-20.
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
F961 − 20
F981 Practice for Assessment of Compatibility of Biomaterials for Surgical Implants with Respect to Effect of Materials on
Muscle and Insertion into Bone
IEEE/ASTM SI 10 American National Standard for Use of the International System of Units (SI): The Modern Metric System
2.2 ISO Standards:
ISO 5832-6 Implants for Surgery–Metallic Materials–Part 6: Wrought Cobalt-Nickel-Chromium-Molybdenum Alloy
ISO 9001 Quality Management Systems—Requirements
ISO 13485 Medical Devices—Quality Management Systems—Requirements for Regulatory Purposes
2.3 American Society for Quality Control Standard:
ASQ C1 Specification of General Requirements for a Quality Program
3. Terminology
3.1 Definitions of Terms Specific to This Standard:
3.1.1 lot, n—the total number of forgings produced from the same heat under the same conditions at essentially the same time.
4. Ordering Information
4.1 Inquiries and orders for forgings under this specification shall include the following information:
4.1.1 Quantity,Quantity;
4.1.2 ASTM designation and date of issue,issue;
4.1.3 Mechanical properties (if applicable, for special conditions),conditions);
4.1.4 Form, Form (bar or wire);
4.1.5 Applicable dimensions, including size, thickness, width, and length (exact, random, or multiples), or drawing
number,number;
4.1.6 Tolerances—Condition,Unless otherwise specified by purchaser, tolerances must meet the requirements of Specification
A484/A484M, Specification A555/A555M, or both, as applicable;
4.1.7 Finish,Condition (see 5.1);
4.1.8 Finish;
4.1.9 Special tests (if any),any); and
4.1.10 Other requirements.
5. Materials and Manufacture
5.1 Material for forgings shall be bars or wire fabricated in accordance with Specification F562 or Specification F688. The
material shall be generally in the solution-annealed condition with a finish suitable for forging.
5.1 The material shall be forged by hammering, pressing, extruding, or upsetting and shall be processed, if practicable, so as
to cause metal flow during the hot working operation in the direction most favorable for resisting stresses encountered in service,
as may be indicated to the fabricator by the purchaser.Condition:
5.1.1 Material for forgings shall be bars or wire fabricated in accordance with Specification F562 or Specification F688. The
material shall be generally in the solution-annealed condition with a finish suitable for forging.
5.1.2 The material shall be forged by hammering, pressing, extruding, or upsetting and shall be processed, if practicable, so as
to cause metal flow during the hot working operation in the direction most favorable for resisting stresses encountered in service,
as may be indicated to the fabricator by the purchaser.
5.2 Forgings shall be free of splits, scale, cracks, inequalities, flaws, and other imperfections not consistent with good
commercial practice. (See Note 1.) Offset or mismatch allowance, dependent upon part size and configuration, shall be within
standard forging tolerances. Finish:
NOTE 1—Compliance to these requirements may be verified by Test Method E165 or Practice F601 or other suitable method.
5.2.1 Forgings shall be free of splits, scale, cracks, inequalities, flaws, and other imperfections not consistent with good
commercial practice. (See Note 1.) Offset or mismatch allowance, dependent upon part size and configuration, shall be within
standard forging tolerances.
NOTE 1—Compliance to these requirements may be verified by Practice E165 or Practice F601 or other suitable method.
5.2.2 After all hot-working operations have been completed, the forgings shall receive an annealing treatment consisting of
heating the parts to an appropriate elevated temperature for a specified dwell time followed by appropriate cooling to meet the
applicable metallurgical requirements specified herein.
5.2.3 Optional identification marks, including the manufacturer’s logo, material designation, heat code number, and impression
number, may be placed upon each forging, the method and location of which shall be as specified by the purchaser.
Available from American National Standards Institute (ANSI), 25 W. 43rd St., 4th Floor, New York, NY 10036, http://www.ansi.org.
F961 − 20
5.4 After all hot-working operations have been completed, the forgings shall receive an annealing treatment consisting of
heating the parts to an appropriate elevated temperature for a specified dwell time followed by appropriate cooling to meet the
applicable metallurgical requirements specified herein.
5.5 Optional identification marks, including the manufacturer’s logo, material designation, heat code number, and impression
number, may be placed upon each forging, the method and location of which shall be as specified by the purchaser.
6. Chemical Requirements
6.1 When specified by the purchaser, the chemical composition of either the forging bars or the completed forgings shall be
determined and confirmed by the forger, and shall meet the product analysis limits of the appropriate material specification.
6.2 For referee purposes, Test Methods E354 and A751 shall be used.
7. Mechanical Requirements
7.1 Tensile Properties:
7.1.1 The mechanical properties of forgings shall be tested by the forger and shall comply with the minimum mechanical
properties as specified in Specification F562.
7.1.2 Test specimens shall be taken from a representative forging if possible, or from a representative forged test bar. A
representative forged test bar may only be used if the configuration is such that a test bar cannot be obtained. Any specially forged
test bar must be annealed with the forgings it represents.
7.1.3 Specimens for tension tests shall be machined and tested in accordance with Test Methods E8/E8M.
7.2 Number of Tests:
7.2.1 Perform at
...