ASTM F799-19

Standard Specification for Cobalt-28 Chromium-6 Molybdenum Alloy Forgings for Surgical Implants (UNS R31537, R31538, R31539)

ABSTRACT
This specification covers the material requirements for low-carbon (UNS R31537), high-carbon (UNS R31538), and dispersion-strengthened (UNS R31539) cobalt-28chromium-6molybdenum alloy high-strength forgings used for the manufacture of surgical implants. The properties specified here specifically apply to finished or semifinished parts that receive no subsequent thermomechanical processing. The materials shall be in the form of bars, rods, or wires suitable for forging by hammering, pressing, rolling, extruding, or upsetting. The forgings shall adhere to chemical composition, ultimate tensile strength, yield strength, elongation, reduction of area, and hardness requirements.
SCOPE
1.1 This specification covers requirements of cobalt-28 chromium-6 molybdenum alloy (UNS R31537, R31538, R31539) high-strength forgings for the manufacture of surgical implants. The properties specified in this document specifically apply to finished or semifinished parts that receive no subsequent thermomechanical processing.  
1.2 Wrought material to be used as forging stock in the manufacture of forgings conforming to this specification, typically hot worked and unannealed with a surface finish suitable for forging, shall be fabricated and supplied in accordance with Specification F1537.  
1.3 Units—The SI units in this standard are the primary units. The values stated in either primary SI units or secondary inch-pound units are to be regarded separately as standard. The values stated in each system may not be exact equivalents; therefore, each system shall be used independently of the other. Combining values from the two systems may result in non-conformance with the standard.  
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: 14-May-2019
• 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 F799-11 - Standard Specification for Cobalt-28Chromium-6Molybdenum Alloy Forgings for Surgical Implants (UNS R31537, R31538, R31539)
• Effective Date: 15-May-2019
• Refers: ASTM E8/E8M-24 - Standard Test Methods for Tension Testing of Metallic Materials
• Effective Date: 01-Jan-2024
• Refers: ASTM E18-18 - Standard Test Methods for Rockwell Hardness of Metallic Materials
• Effective Date: 01-Jul-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 E930-99(2015) - Standard Test Methods for Estimating the Largest Grain Observed in a Metallographic Section (ALA Grain Size)
• Effective Date: 01-Oct-2015
• Refers: ASTM E8/E8M-15 - Standard Test Methods for Tension Testing of Metallic Materials
• Effective Date: 01-Feb-2015
• Refers: ASTM F601-13 - Standard Practice for Fluorescent Penetrant Inspection of Metallic Surgical Implants
• Effective Date: 01-Dec-2013
• Refers: ASTM E8/E8M-13 - Standard Test Methods for Tension Testing of Metallic Materials
• Effective Date: 01-Jun-2013
• Refers: ASTM E18-12 - Standard Test Methods for Rockwell Hardness of Metallic Materials
• Effective Date: 01-Dec-2012
• Refers: ASTM E112-12 - Standard Test Methods for Determining Average Grain Size
• Effective Date: 15-Nov-2012
• Refers: ASTM F75-12 - Standard Specification for Cobalt-28 Chromium-6 Molybdenum Alloy Castings and Casting Alloy for Surgical Implants (UNS R30075)
• Effective Date: 15-May-2012
• Refers: ASTM E8/E8M-11 - Standard Test Methods for Tension Testing of Metallic Materials
• Effective Date: 01-Dec-2011
• Refers: ASTM F1537-11 - Standard Specification for Wrought Cobalt-28Chromium-6Molybdenum Alloys for Surgical Implants (UNS R31537, UNS R31538, and UNS R31539)
• Effective Date: 15-Nov-2011
• Refers: ASTM E18-11 - Standard Test Methods for Rockwell Hardness of Metallic Materials
• Effective Date: 01-Nov-2011

Overview

ASTM F799-19 sets forth the requirements for cobalt-28 chromium-6 molybdenum alloy forgings used in the production of surgical implants. This specification encompasses three alloys identified as UNS R31537 (low carbon), R31538 (high carbon), and R31539 (dispersion strengthened). These high-strength materials are delivered as bars, rods, or wires intended for subsequent forging operations but not for further thermomechanical processing. The specification covers both finished and semifinished parts, ensuring consistency and reliability of components destined for medical device manufacturing.

This standard applies strict criteria to ensure that forgings meet chemical composition, mechanical strength, ductility, and hardness requirements. It is essential for manufacturers of surgical implants to adhere to these guidelines to ensure the safety and performance of medical devices used in clinical settings.

Key Topics

• Alloy Types and Designations

  • UNS R31537: Low-carbon alloy
  • UNS R31538: High-carbon alloy
  • UNS R31539: Dispersion-strengthened alloy

• Material Forms

  • Supplied as bars, rods, or wires suitable for forging by:
    • Hammering
    • Pressing
    • Rolling
    • Extruding
    • Upsetting

• Mechanical and Chemical Requirements

  • Ultimate tensile strength, yield strength, elongation, reduction of area, and hardness must comply with specified limits
  • Minimum Rockwell C hardness: 35 HRC
  • Tested according to ASTM and ISO methods for tensile properties and hardness

• Grain Size and Microstructure

  • Fine-grained structure (ASTM No. 5 or finer) is required for a majority of the section evaluated
  • Specific allowances for unrecrystallized grains under defined conditions

• Testing and Certification

  • Mechanical testing, chemical analysis, and optional penetrant inspections
  • Certification of conformance and test results must accompany shipments

• Quality Management

  • Suppliers and processors must maintain a quality program according to ASQ C1 or ISO 9001

Applications

• Surgical and Orthopedic Implants

  • Used in the manufacturing of critical components such as joint replacements, bone plates, and fixation devices
  • Chosen for superior corrosion resistance, mechanical strength, and proven biocompatibility in long-term implant applications

• Medical Device Manufacturing

  • Forgings produced under ASTM F799-19 provide consistent mechanical properties and microstructure suitable for end-use medical devices
  • Applies to devices where no additional thermomechanical processing will occur after forging

Related Standards

Manufacturers, suppliers, and industry professionals working with ASTM F799-19 should be aware of the following related standards:

• ASTM F75: Specification for Cobalt-28 Chromium-6 Molybdenum Alloy Castings for surgical implants
• ASTM F1537: Specification for wrought cobalt-chromium-molybdenum alloys for surgical implants
• ASTM E8/E8M: Test methods for tension testing of metallic materials
• ASTM E18: Test methods for Rockwell hardness of metallic materials
• ASTM E112: Grain size determination
• ASTM E165/E165M and F601: Liquid and fluorescent penetrant inspection methods
• ASTM F981: Assessment of biocompatibility with respect to muscle and bone
• ISO 6892-1: Tensile testing for metallic materials at ambient temperature
• ISO 9001: Quality management system requirements
• ASQ C1: Quality program requirements

By following ASTM F799-19, manufacturers ensure high standards of material quality, mechanical performance, and patient safety for surgical implant applications, aligning with globally recognized benchmarks for medical device components.

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: F799 −19
Standard Specification for
Cobalt-28 Chromium-6 Molybdenum Alloy Forgings for
Surgical Implants (UNS R31537, R31538, R31539)
ThisstandardisissuedunderthefixeddesignationF799;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* E29 Practice for Using Significant Digits in Test Data to
Determine Conformance with Specifications
1.1 This specification covers requirements of cobalt-28
E112 Test Methods for Determining Average Grain Size
chromium-6 molybdenum alloy (UNS R31537, R31538,
E165/E165M Practice for Liquid Penetrant Testing for Gen-
R31539)high-strengthforgingsforthemanufactureofsurgical
eral Industry
implants.The properties specified in this document specifically
E930 Test Methods for Estimating the Largest Grain Ob-
apply to finished or semifinished parts that receive no subse-
served in a Metallographic Section (ALA Grain Size)
quent thermomechanical processing.
F75 Specification for Cobalt-28 Chromium-6 Molybdenum
1.2 Wrought material to be used as forging stock in the
Alloy Castings and Casting Alloy for Surgical Implants
manufacture of forgings conforming to this specification,
(UNS R30075)
typically hot worked and unannealed with a surface finish
F601 Practice for Fluorescent Penetrant Inspection of Me-
suitable for forging, shall be fabricated and supplied in
tallic Surgical Implants
accordance with Specification F1537.
F981 Practice for Assessment of Compatibility of Biomate-
rials for Surgical Implants with Respect to Effect of
1.3 Units—The SI units in this standard are the primary
units. The values stated in either primary SI units or secondary Materials on Muscle and Insertion into Bone
F1537 Specification for Wrought Cobalt-28Chromium-
inch-pound units are to be regarded separately as standard.The
values stated in each system may not be exact equivalents; 6Molybdenum Alloys for Surgical Implants (UNS
R31537, UNS R31538, and UNS R31539)
therefore,eachsystemshallbeusedindependentlyoftheother.
Combining values from the two systems may result in non- IEEE/ASTM SI 10 American National Standard for Use of
theInternationalSystemofUnits(SI):TheModernMetric
conformance with the standard.
System
1.4 This international standard was developed in accor-
2.2 ISO Standards:
dance with internationally recognized principles on standard-
ISO 6892-1 Metallic materials – Tensile testing – Part 1:
ization established in the Decision on Principles for the
Method of test at room temperature
Development of International Standards, Guides and Recom-
ISO 9001 Quality management systems – Requirements
mendations issued by the World Trade Organization Technical
Barriers to Trade (TBT) Committee.
3. Terminology
2. Referenced Documents
3.1 Definitions of Terms Specific to This Standard:
3.1.1 lot, n—the total number of forgings produced from the
2.1 ASTM Standards:
same heat of starting material under the same conditions at
E8/E8M Test Methods for Tension Testing of Metallic Ma-
essentially the same time.
terials
E18 Test Methods for Rockwell Hardness of Metallic Ma-
4. Ordering Information
terials
4.1 Inquiries and orders for material under this specification
shall include the following information:
This specification is under the jurisdiction of ASTM Committee F04 on
4.1.1 Quantity, number of pieces
Medical and Surgical Materials and Devices and is the direct responsibility of
Subcommittee F04.12 on Metallurgical Materials. 4.1.2 ASTM designation, date of issue, and alloy number,
Current edition approved May 15, 2019. Published June 2019. Originally
4.1.3 Units to be certified (SI or inch-pound),
approved in 1982. Last previous edition approved in 2011 as F799 – 11. DOI:
4.1.4 Condition,
10.1520/F0799-19.
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
F799 − 19
4.1.5 Mechanical properties, specimensmayhaveagroundfinishonthereducedsectionand
4.1.6 Finish, may be taken in a direction parallel to the long axis of the
4.1.7 Applicable dimensions or drawing number, finished or semi-finished part.
4.1.8 Special tests, if any, and 7.1.4 A minimum of two tension test specimens shall be
4.1.9 Other requirements.
tested. Should either of the two specimens not meet the
specified requirements, two additional specimens shall be
5. Materials and Manufacture
tested and both must pass.
7.1.5 If any fracture takes place outside the middle half of
5.1 Materials for forgings shall be bar, rod, or wire fabri-
cated in accordance with Specification F1537. the gauge length or in a punched or scribed gauge mark within
the reduced section, the elongation value obtained may not be
5.2 The material shall be forged by hammering, pressing,
representative of the material. In acceptance testing, if the
rolling, extruding, or upsetting, and shall be processed, if
elongation so measured meets the minimum requirements
practical, so as to cause metal flow during the hot-working
specified, no further testing is required, but if the elongation is
operation to be in the most favorable direction for resisting
lessthantheminimumrequirements,discardthetestandretest.
stresses encountered in service, as may be indicated to the
7.1.6 In some instances, mechanical test pieces may not be
supplier by the purchaser.
obtainable directly from forged parts due to their configuration
5.3 Forgings shall be free of splits, scale, cracks, flaws, and
or small size. Instead of mechanical testing, these parts shall
other imperfections not consistent with good commercial
exhibit hardness of HRC 35 to 45 when tested in accordance
practice(seeNote1).Offsetormismatchallowance,dependent
with Test Methods E18.
upon part size and configuration, shall be within standard
7.2 Hardness—Forgings conforming to this specification
forging tolerances.
shall have a minimum Rockwell C hardness of 35 HRC. The
5.4 Optional identification marks, including the purchaser’s
hardness determination shall be performed in accordance with
logo, material designation, heat code number, and impression
Test Methods E18.
number, may be placed upon each forging, the method and
location of which shall be as specified by the purchaser.
8. Dimensions and Permissible Variations
NOTE 1—Compliance with these requirements may be verified by
8.1 Units of Measure:
Practice E165/E165M or Practice F601, or other suitable methods.
8.1.1 Selection—This specification requires that the pur-
chaser selects the units (SI or inch-pound) to be used for
6. Chemical Requirements
product certification. In the absence of a stated selection of
6.1 The cobalt-28 chromium-6 molybdenum alloy forgings
units on the purchase order, this selection may be expressed by
shall conform to the chemical requirements prescribed in
the purchaser in several alternate forms listed in order of
Table 1 of Specification F1537. The supplier shall not ship
precedence.
material that is outside the limits specified in Table 1 of
8.1.1.1 If the purchaser and supplier have a history of using
Specification F1537 for the applicable alloys. Specification
specific units, these units shall continue to be certified until
F1537 contains three alloys:
expressly changed by the purchaser.
Alloy 1 Low Carbon (UNS R31537)
8.1.1.2 In the absence of historic precedence, if the units
Alloy 2 High Carbon (UNS R31538)
used to define the product on the purchaser’s purchase order,
Alloy 3 Dispersion Strengthened (UNS R31539)
specification, and engineering drawing are consistent, these
7. Mechanical Requirements
units shall be used by the supplier for product certification
8.1.1.3 If the purchaser’s selection of units is unclear, the
7.1 Tensile Properties:
7.1.1 Tensile properties shall be determined in accordance units of measure shall be agreed upon between the purchaser
and supplier.
with Test Methods E8/E8M.
7.1.2 The mecha
...

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: F799 − 11 F799 − 19
Standard Specification for
Cobalt-28Chromium-6Molybdenum Cobalt-28 Chromium-6
Molybdenum Alloy Forgings for Surgical Implants (UNS
R31537, R31538, R31539)
This standard is issued under the fixed designation F799; 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 requirements of cobalt-28chromium-6molybdenum cobalt-28 chromium-6 molybdenum alloy
(UNS R31537, R31538, R31539) high-strength forgings for the manufacture of surgical implants. The properties specified in this
document specifically apply to finished or semifinished parts that receive no subsequent thermomechanical processing.
1.2 Wrought material to be used as forging stock in the manufacture of forgings conforming to this specification, typically hot
worked and unannealed with a surface finish suitable for forging, shall be fabricated and supplied in accordance with Specification
F1537.
1.3 Units—The SI units in this standard are the primary units. The values stated in either primary SI units or secondary
inch-pound units are to be regarded separately as standard. The values stated in each system may not be exact equivalents;
therefore, each system shall be used independently of the other. Combining values from the two systems may result in
non-conformance with the standard.
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:
E8E8/E8M Test Methods for Tension Testing of Metallic Materials [Metric] E0008_E0008M
E18 Test Methods for Rockwell Hardness of Metallic Materials
E29 Practice for Using Significant Digits in Test Data to Determine Conformance with Specifications
E112 Test Methods for Determining Average Grain Size
E165E165/E165M Practice for Liquid Penetrant Testing for General Industry
E930 Test Methods for Estimating the Largest Grain Observed in a Metallographic Section (ALA Grain Size)
F75 Specification for Cobalt-28 Chromium-6 Molybdenum Alloy Castings and Casting Alloy for Surgical Implants (UNS
R30075)
F601 Practice for Fluorescent Penetrant Inspection of Metallic Surgical Implants
F981 Practice for Assessment of Compatibility of Biomaterials for Surgical Implants with Respect to Effect of Materials on
Muscle and Insertion into Bone
F1537 Specification for Wrought Cobalt-28Chromium-6Molybdenum Alloys for Surgical Implants (UNS R31537, UNS
R31538, and UNS R31539)
ASTMIEEE/ASTM SI 10 American National Standard for Use of the International System of Units (SI): The Modern Metric
System
2.2 ISO Standards:
ISO 68926892-1 Metallic Materials—Tensile Testing at Ambient Temperaturematerials – Tensile testing – Part 1: Method of test
at room temperature
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 June 1, 2011May 15, 2019. Published June 2011 June 2019. Originally approved in 1982. Last previous edition approved in 20062011 as F799
– 06.11. DOI: 10.1520/F0799-11.10.1520/F0799-19.
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.
Available from American National Standards Institute (ANSI), 25 W. 43rd St., 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
F799 − 19
ISO 9001 Quality Management Systems—Requirements management systems – Requirements
2.3 American Society for Quality 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 of starting material under the same conditions at
essentially the same time.
4. Ordering Information
4.1 Inquiries and orders for material under this specification shall include the following information:
4.1.1 Quantity, number of pieces
4.1.2 ASTM designation, date of issue, and alloy number,
4.1.3 Units to be certified (SI or inch-pound),
4.1.4 Condition,
4.1.5 Mechanical properties,
4.1.6 Finish,
4.1.7 Applicable dimensions or drawing number,
4.1.8 Special tests, if any, and
4.1.9 Other requirements.
5. Materials and Manufacture
5.1 Materials for forgings shall be bar, rod, or wire fabricated in accordance with Specification F1537.
5.2 The material shall be forged by hammering, pressing, rolling, extruding, or upsetting, and shall be processed, if practical,
so as to cause metal flow during the hot-working operation to be in the most favorable direction for resisting stresses encountered
in service, as may be indicated to the supplier by the purchaser.
5.3 Forgings shall be free of splits, scale, cracks, 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.
5.4 Optional indentificationidentification marks, including the purchaser’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.
NOTE 1—Compliance towith these requirements may be verified by Test Method Practice E165E165/E165M or Practice F601, or other suitable
methods.
6. Chemical Requirements
6.1 The cobalt-28chromium-6molybdenum cobalt-28 chromium-6 molybdenum alloy forgings shall conform to the chemical
requirements prescribed in Table 1 of Specification F1537. The supplier shall not ship material that is outside the limits specified
in Table 1 of Specification F1537 for the applicable alloys. Specification F1537 contains three alloys:
Alloy 1 Low Carbon (UNS R31537)
Alloy 2 High Carbon (UNS R31538)
Alloy 3 Dispersion Strengthened (UNS R31539)
7. Mechanical Requirements
7.1 Tensile Properties:
7.1.1 Tensile properties shall be determined in accordance with Test Methods E8E8/E8M.
7.1.2 The mechanical properties of test specimens prepared from finished or semifinished parts shall conform to the
requirements in Table 1.
7.1.3 Tension test specimens shall be produced from finished or semifinishedsemi-finished parts or from material having the
same process history as that which exists in the final forging. Tension specimens may have a ground finish on the reduced section
and may be taken in a direction parallel to the long axis of the finished or semifinishedsemi-finished part.
7.1.4 A minimum of two tension test specimens shall be tested. Should either of the two specimens not meet the specified
requirements, two additional specimens shall be tested and both must pass.
7.1.5 If any fracture takes place outside the middle half of the gauge length or in a punched or scribed gauge mark within the
reduced section, the elongation value obtained may not be representative of the material. In acceptance testing, if the elongation
so measured meets the minimum requirements specified, no further testing is required, but if the elongation is less than the
minimum requirements, discard the test and retest.
F799 − 19
TABLE 1 Mechanical Requirements
Ultimate Tensile Yield Strength
A
Reduction in Hardness,
Elongation, in 2 in. or
Strength, min, (0.2 % offset),
4D or 4W, min %
Area, min, % HRC, min
psi, (MPa) min, psi (MPa)
170 000 (1172) 120 000 (827) 12 12 35
TABLE 1 Mechanical Requirements
A
Ultimate Tensile Yield Strength
Elongation, in 50.8
Reduction in Hardness,
Strength, min, (0.2 % offset), mm (2 in.) or 4D or
Area, min, % HRC, min
4W, min, %
MPa (psi) min, MPa (psi )
1172 [170 000] 827 (120 000) 12 12 35
A
ElongationElongation of material 0.063 in. (1.6 mm)1.575 mm (0.062 in.) or greater in diameter (D) or width (W) shall be measured using a gaugegage length of 2 in.
50.8 mm (2 in.) or 4D or 4W. The gaugegage length mustshall be reported with the test results. The method for determining elongation of material under 0.063 in. (1.6
mm)1.575 mm (0.062 in.) in diameter or thickness may be negotiated. Alternately,Alternatively, a gaugegage length corresponding to ISO 6892 6892-1 (5.65 times the
square root of S , where S is the original cross-sectional area) may be used when agreed upon between the supplier and purchaser. (5.65 sqaure root So, where So
O O
is the original cross sectional area.)
7.1.6
...