ASTM B657-92(2000)

Standard Test Method for Metallographic Determination of Microstructure in Cemented Tungsten Carbides

SCOPE
1.1 This test method covers apparatus and procedures for the metallographic determination of microstructures in cemented tungsten carbides.  
1.2  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 and health practices and determine the applicability of regulatory limitations prior to use. Precautions applying to use of hazardous laboratory chemicals should be observed for chemicals specified in Table 1.

General Information

• Status: Historical
• Publication Date: 31-Dec-1999
• ICS: 77.160 - Powder metallurgy
• Technical Committee: B09 - Metal Powders and Metal Powder Products
• Drafting Committee: B09.06 - Cemented Carbides

Relations

• Replaces: ASTM B657-92(1996)e1 - Standard Test Method for Metallographic Determination of Microstructure in Cemented Tungsten Carbides
• Effective Date: 01-Jan-2000
• Replaced By: ASTM B657-05 - Guide for Metallographic Identification of Microstructure in Cemented Carbides
• Effective Date: 01-Oct-2005
• Referred By: ASTM B665-19 - Standard Guide for Metallographic Sample Preparation of Cemented Tungsten Carbides
• Effective Date: 01-Jan-2000
• Referred By: ASTM B930-03(2021) - Standard Test Method for Rating Grain Size and Frequency of Abnormally Large Grains in Cemented Tungsten Carbides (Hardmetals)
• Effective Date: 01-Jan-2000

Standards Content (Sample)

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information
Designation:B657–92 (Reapproved 2000)
Standard Test Method for
Metallographic Determination of Microstructure in Cemented
Tungsten Carbides
This standard is issued under the fixed designation B 657; 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 (e) indicates an editorial change since the last revision or reapproval.
1. Scope producersandusersmayusethemicrostructuralinformationas
a guide in developing their own specifications.
1.1 This test method covers apparatus and procedures for
the metallographic determination of microstructures in ce-
5. Apparatus
mented tungsten carbides.
5.1 Metallographic Microscope capable of magnifications
1.2 This standard does not purport to address all of the
up to 1500 times.
safety concerns, if any, associated with its use. It is the
5.2 Ordinary metallurgical laboratory equipment.
responsibility of the user of this standard to establish appro-
5.3 Equipment for specimen preparation as outlined in
priate safety and health practices and determine the applica-
Practice B 665.
bility of regulatory limitations prior to use. Precautions apply-
ing to use of hazardous laboratory chemicals should be
6. Specimen Preparation
observed for chemicals specified in Table 1.
6.1 A suitable procedure is described in Practice B 665.
2. Referenced Documents
7. Procedure
2.1 ASTM Standards:
7.1 Examine the microstructure by gradual development of
B 665 Practice for Metallographic Sample Preparation of
2 the phases by etching. Examples of suitable etching techniques
Cemented Tungsten Carbides
are given in Table 1.
2.2 ISO Standard:
7.2 Determine the presence of h-type phases by lightly
ISO 4499 Hardmetals—Metallographic Determination of
3 etching the section with Technique 1 (see Table 1). Phases of
Microstructure
h-type are colored orange to brown. g-Phase may etch lightly,
3. Terminology while the other phases remain unetched. Etching by Technique
1 does not preclude subsequent etching by Techniques 2 or 3.
3.1 Definitions of Symbols:
Examine the entire section at low magnification and, if
Symbol Definition
necessary, at magnifications up to 1500 times. Note and record
a phase tungsten carbide
b phase binder (for example, Co, Ni, Fe)
the existence of h-type phases and their distribution.
g phase carbide of a cubic lattice (for example, TiC, TaC, NbC)
7.3 Determine the presence of g phases by etching with
that may contain other carbides (for example, WC) in
Technique 2 (Table 1). This phase appears light yellowish
solid solution
h-type phases multiple carbides of tungsten and at least one metal of the
brown and has a typically rounded shape (see Fig. 1). Examine
binder
the etched section and note and record the existence of a g
phase. Estimate and record its size according to Fig. 1 as
4. Significance and Use
g–fine, g– medium, or g–coarse.
4.1 The microstructure of cemented tungsten carbide affects
7.4 Determine the presence of a phase by etching the
the material’s mechanical and physical properties. This is not
section with Technique 3, or in case g phase is present, with
intended to be used as a specification for carbide grades,
Technique 2. The a phase appears gray. Examine the etched
section and note and record the presence of a phase. Estimate
and record its size according to Fig. 2 as a–fine, a–medium, or
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-
a–coarse.
mittee B09.06 on Cemented Carbides.
7.5 Identify t
...