ASTM B887-24

Standard Test Method for Determination of Coercivity (Hcs) of Cemented Carbides

SIGNIFICANCE AND USE
5.1 Measurement of coercivity provides a relative comparison of carbide grain size, binder content, and possibly carbon deficiency for a given graded carbide material or product, and may be employed as a non-destructive measurement indicating deviation from a specified norm.  
5.2 This test method allows the non-destructive estimate of average carbide grain size in sintered cemented carbide hardmetals. It is appropriate for a wide range of compositions and tungsten carbide (WC) WC grain sizes, and can be used for acceptance of material or product to specification.
SCOPE
1.1 This test method covers the determination of magnetization coercivity (Hcs) of cemented carbide materials and products using coercive force instrumentation. It is patterned after ISO 3326.  
1.2 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.  
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-2024
• ICS: 77.160 - Powder metallurgy
• Technical Committee: B09 - Metal Powders and Metal Powder Products
• Drafting Committee: B09.06 - Cemented Carbides

Relations

• Replaces: ASTM B887-12(2019) - Standard Test Method for Determination of Coercivity (Hcs) of Cemented Carbides
• Effective Date: 01-Feb-2024

Overview

ASTM B887-24: Standard Test Method for Determination of Coercivity (Hcs) of Cemented Carbides establishes the procedures for determining the magnetization coercivity (Hcs) of cemented carbide materials and products. This non-destructive test provides a crucial quality assessment for sintered cemented carbides, widely used in hardmetals and tungsten carbide products. The standard enables manufacturers and quality control laboratories to estimate factors such as carbide grain size, binder content, and potential carbon deficiency, all of which impact carbide performance.

This test method employs coercive force instrumentation to measure the magnetic field strength required to reduce magnetization in the sample to zero. It is based on internationally recognized standardization principles and closely follows ISO 3326 protocols. All measurements are to be recorded in SI units, ensuring global compatibility and consistency.

Key Topics

• Coercivity (Hcs) Measurement
  This method evaluates the magnetizing force needed to demagnetize cemented carbide materials, serving as a bulk indicator of microstructural properties.

• Quality and Compliance Assessment
  The test supports compliance with product specifications by detecting deviations in carbide grain size, binder content, and material uniformity, often serving as a quality control tool in the production of tungsten carbide and related hardmetals.

• Non-Destructive Technique
  The method is non-destructive, preserving valuable samples and enabling repeated tests or further metallurgical evaluation.

• Instrument Calibration and Reference Materials
  Calibration is typically conducted with internal reference materials representative of the test samples. Soft magnetic (e.g., Ni-Fe alloys) and hard ferromagnetic materials are recommended for instrument validation.

• Measurement Influences
  Factors such as sample shape, aspect ratio, compositional variation, cooling rate, grain contiguity, and residual stress can affect coercivity measurements. Careful sample preparation and positioning are crucial for accurate and repeatable results.

Applications

ASTM B887-24 is applied across industries dealing with cemented carbide products, including:

• Hardmetal Manufacturing:
  Used in quality control to verify material properties and detect deviations from prescribed grain size or binder content in products such as cutting tools, wear parts, and mining equipment.

• Materials Research and Development:
  Enables material scientists to investigate the relationship between magnetic properties and microstructural features, accelerating the development of advanced cemented carbides.

• Incoming Inspection:
  Allows end-users to perform acceptance testing on received carbide materials, ensuring product meets specified coercivity standards before use.

• Process Monitoring:
  Supports ongoing monitoring of production stability, with routine Hcs measurements to detect subtle shifts in process parameters affecting material quality.

Related Standards

In addition to ASTM B887-24, several related standards and references support the determination of coercivity in cemented carbides:

• ISO 3326: Hardmetals - Determination of Magnetization Coercivity
• ASTM A340: Terminology of Symbols and Definitions Relating to Magnetic Testing
• ASTM B243: Terminology of Powder Metallurgy
• ASTM E177: Practice for Use of the Terms Precision and Bias in ASTM Test Methods
• ASTM E691: Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method

Practical Value

Implementing ASTM B887-24 helps manufacturers and laboratories:

• Maintain consistency in product quality for carbide tools and components
• Detect undesirable variations in microstructure that can affect tool life and performance
• Comply with rigorous material certification and traceability requirements
• Reduce waste and costs by employing a non-destructive testing method for high-value materials

Incorporating this coercivity test method strengthens quality assurance programs for cemented carbide materials and aligns production with international standards, fostering trust and reliability throughout the supply chain.

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: B887 − 24
Standard Test Method for
Determination of Coercivity (Hcs) of Cemented Carbides
This standard is issued under the fixed designation B887; 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* 3. Terminology
1.1 This test method covers the determination of magneti- 3.1 Definitions:
zation coercivity (Hcs) of cemented carbide materials and 3.1.1 For definition of terms used in this procedure refer to
products using coercive force instrumentation. It is patterned Terminology A340 and Terminology B243.
after ISO 3326. 3.1.2 dc—direct current.
1.2 The values stated in SI units are to be regarded as
4. Summary of Test Method
standard. No other units of measurement are included in this
4.1 A test sample is positioned in the dc magnetic field of
standard.
the test apparatus and magnetized to technical saturation. The
1.3 This standard does not purport to address all of the
magnetic field polarity is then reversed and the test sample is
safety concerns, if any, associated with its use. It is the
demagnetized by increasing the energy of the reversed mag-
responsibility of the user of this standard to establish appro-
netic field until the test sample reaches zero magnetism. The
priate safety, health, and environmental practices and deter-
coercive force (Hc) is the magnetizing force required to return
mine the applicability of regulatory limitations prior to use.
the saturated magnetic induction to zero.
1.4 This international standard was developed in accor-
dance with internationally recognized principles on standard-
5. Significance and Use
ization established in the Decision on Principles for the
5.1 Measurement of coercivity provides a relative compari-
Development of International Standards, Guides and Recom-
son of carbide grain size, binder content, and possibly carbon
mendations issued by the World Trade Organization Technical
deficiency for a given graded carbide material or product, and
Barriers to Trade (TBT) Committee.
may be employed as a non-destructive measurement indicating
2. Referenced Documents deviation from a specified norm.
2.1 ASTM Standards: 5.2 This test method allows the non-destructive estimate of
A340 Terminology of Symbols and Definitions Relating to average carbide grain size in sintered cemented carbide hard-
Magnetic Testing metals. It is appropriate for a wide range of compositions and
B243 Terminology of Powder Metallurgy tungsten carbide (WC) WC grain sizes, and can be used for
E177 Practice for Use of the Terms Precision and Bias in acceptance of material or product to specification.
ASTM Test Methods
6. Interferences
E691 Practice for Conducting an Interlaboratory Study to
Determine the Precision of a Test Method
6.1 Hcs measurement is a non-destructive “bulk” measure-
2.2 ISO Standard:
ment that is averaged over the specimen volume. Bi-modal
ISO 3326 Hardmetals - Determination of (the Magnetiza-
grain size distributions will give approximately the same Hc
tion) Coercivity
value as would be obtained from a normal grain size distribu-
tion about the same mean value.
6.2 Large test specimens must be sized to fit within the
This test method is under the jurisdiction of ASTM Committee B09 on Metal
Powders and Metal Powder Products and is the direct responsibility of Subcom-
magnetic field coil spacing available for the apparatus em-
mittee B09.06 on Cemented Carbides.
ployed.
Current edition approved Feb. 1, 2024. Published February 2024. Originally
approved in 1998. Last previous edition approved in 2019 as B887 – 12 (2019).
6.3 Small test specimens may be immeasurable if their size
DOI: 10.1520/B0887-24.
prohibits detection by the magnetic field coils for the apparatus
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
employed.
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
Standards volume information, refer to the standard’s Document Summary page on
6.4 Specimen shape, that is, symmetry and aspect ratio,
the ASTM website.
influence Hc measurement values and repeatability of results.
Available from American National Standards Institute (ANSI), 25 W. 43rd St.,
4th Floor, New York, NY 10036, http://www.ansi.org. Test specimens should be positioned with their long axis in the
*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
B887 − 24
direction of the magnetic field. Asymmetrically shaped test 10. Report
specimens should be tested in several positions, the measure-
10.1 Report the following information:
ment values recorded, and the average value reported.
10.1.1 Test sample identification,
10.1.2 Average Hcs coercivity (amp per metre (A/m) or
6.5 Compositional variation of the binder in hardmetal due
oersteds), and
to cooling rate can affect Hc. For instance, formation of Co W
10.1.3 Range of measured Hc values, especially for repli-
precipitate in the binder phase during aging of hardmetal after
cate measurements of asymmetric sample shapes.
fast cooling can significantly change Hc of the material.
6.6 Difference in contiguity of hard particles in hardmetal
11. Precision and Bias
can affect Hc. For instance, two materials with different
11.1 The precision of this test method is based on an
WC/WC contiguity but similar WC grain size will have
interlaboratory study of ASTM B887- Standard Test Method
different interphase areas and different Hc values.
for Determination of Coercivity (Hcs) of Cemented Carbides,
6.7 Deformation and residual stresses affect Hc. Deformed conducted in 2010. Three laboratories participated in this
study, recording the coercivity on three specimens each, of ten
hardmetal shows a significant increase in Hc due to deforma-
different materials. This procedure was performed three times
tion of its binder phase. Tumbling which is a standard method
on each material in order to determine the precision of the test
used for imparting residual stress into hardmetal, increases Hc.
method. Every “test result” represents an individual observa-
tion. Except for the limited number of participating
7. Apparatus
laboratories, Practice E691 was followed for the design and
7.1 Instrumentation capable of the dc m
...

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: B887 − 12 (Reapproved 2019) B887 − 24
Standard Test Method for
Determination of Coercivity (Hcs) of Cemented Carbides
This standard is issued under the fixed designation B887; 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 test method covers the determination of magnetization coercivity (Hcs) of cemented carbide materials and products using
coercive force instrumentation. It is patterned after ISO 3326.
1.2 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
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:
A340 Terminology of Symbols and Definitions Relating to Magnetic Testing
B243 Terminology of Powder Metallurgy
E177 Practice for Use of the Terms Precision and Bias in ASTM Test Methods
E691 Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method
2.2 ISO Standard:
ISO 3326 Hardmetals - Determination of (the Magnetization) Coercivity
3. Terminology
3.1 Definitions:
3.1.1 For definition of terms used in this procedure refer to Terminology A340 and Terminology B243.
3.1.2 dc—direct current.
4. Summary of Test Method
4.1 A test sample is positioned in the dc magnetic field of the test apparatus and magnetized to technical saturation. The magnetic
This test method is under the jurisdiction of ASTM Committee B09 on Metal Powders and Metal Powder Products and is the direct responsibility of Subcommittee B09.06
on Cemented Carbides.
Current edition approved April 1, 2019Feb. 1, 2024. Published April 2019February 2024. Originally approved in 1998. Last previous edition approved in 20122019 as
B887 – 12.B887 – 12 (2019). DOI: 10.1520/B0887-12R19.10.1520/B0887-24.
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
B887 − 24
field polarity is then reversed and the test sample is demagnetized by increasing the energy of the reversed magnetic field until the
test sample reaches zero magnetism. The coercive force (Hc) is the magnetizing force required to return the saturated magnetic
induction to zero.
5. Significance and Use
5.1 Measurement of coercivity provides a relative comparison of carbide grain size, binder content, and possibly carbon deficiency
for a given graded carbide material or product, and may be employed as a non-destructive measurement indicating deviation from
a specified norm.
5.2 This test method allows the non-destructive estimate of average carbide grain size in sintered cemented carbide hardmetals.
It is appropriate for a wide range of compositions and tungsten carbide (WC) WC grain sizes, and can be used for acceptance of
material or product to specification.
6. Interferences
6.1 Hcs measurement is a non-destructive “bulk” measurement that is averaged over the specimen volume. Bi-modal grain size
distributions will give approximately the same Hc value as would be obtained from a normal grain size distribution about the same
mean value.
6.2 Large test specimens must be sized to fit within the magnetic field coil spacing available for the apparatus employed.
6.3 Small test specimens may be immeasurable if their size prohibits detection by the magnetic field coils for the apparatus
employed.
6.4 Specimen shape, that is, symmetry and aspect ratio, influence Hc measurement values and repeatability of results. Test
specimens should be positioned with their long axis in the direction of the magnetic field. Asymmetrically shaped test specimens
should be tested in several positions, the measurement values recorded, and the average value reported.
6.5 Compositional variation of the binder in hardmetal due to cooling rate can affect Hc. For instance, formation of Co W
precipitate in the binder phase during aging of hardmetal after fast cooling can significantly change Hc of the material.
6.6 Difference in contiguity of hard particles in hardmetal can affect Hc. For instance, two materials with different WC/WC
contiguity but similar WC grain size will have different interphase areas and different Hc values.
6.7 Deformation and residual stresses affect Hc. Deformed hardmetal shows a significant increase in Hc due to deformation of its
binder phase. Tumbling which is a standard method used for imparting residual stress into hardmetal, increases Hc.
7. Apparatus
7.1 Instrumentation capable of the dc magnetization of appropriately sized test samples to technical saturation and accurate
measurement of the energy required to restore the magnetic induction to zero.
8. Standards
8.1 No certified cemented carbide standards, powder materials or sintered product, are available for Hc measurement. Most
common practice is the development of (internal) reference materials representative of the test samples being evaluated.
8.2 Soft magnetic material (50 percent Ni – 50 percent Fe alloy) with low Hc and hard ferromagnetic material with high Hc are
recommended for calibrating the instrument.
9. Procedure
9.1 For commercial instrumentation, refer to the equipment operators manual and follow the manufacturer’s operating
instructions.
B887 − 24
9.2 Position the test sample in the center of the
...