GB/T 33488.1-2017 Hardmetals - Metallographic determination of microstructure Part 1: Photomicrographs and description
1 Scope
This part specifies the methods of metallographic determination of the microstructure of hardmetals using photomicrographs.
2 Normative references
The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.
ISO 3878:1983 Hardmetals - Vickers hardness test
ISO 4499-2 Hardmetals - Metallographic determination of microstructure - Part 2: Measurement of WC grain size
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
α-phase
tungsten carbide
3.2
β-phase
binder phase (for example, based on Co, Ni, Fe)
3.3
γ-phase
carbide having a cubic lattice (for example, TiC, TaC) which may contain other carbides (for example WC) in solid solution
4 Apparatuses
4.1 Metallographic microscope, permitting observations at magnifications up to 1 500 x.
4.2 Scanning electron microscope for magnification over 1 500 x.
4.3 Equipment for preparation of testpiece sections.
5 Preparation of testpiece section
The testpiece section shall be prepared as for metallographic examination,and the surface to be examined shall be free from grinding and polishing marks.Care shall be taken to avoid tearing-out of particles,which may lead to a wrong evaluation of microstructure.
Note: There are several methods for preparation of hard metal surfaces for metallographic examination. Firstly, careful coarse grinding is carried out to remove sufficient material to ensure that the true structure is revealed. After grinding with fine diamond-grit wheels,polishing is effected by using diamond paste or diamond powders,of progressively finer grain size down to 1 μm,on rigidly supported laps of,for example,thin plastic,thin felt or paper.
6 Procedure
6.1 Metallographic preparation
6.1.1 General
6.1.1.1 Good metallographic preparation is essential to produce a plane polished sample that when etched reveals the true microstructure of the hard metal. Bad preparation can lead to grain tear-out, uneven etching and misleading detail in the microstructure which will affect any subsequent measurement.
6.1.1.2 Preparation and etching procedures may require toxic or dangerous chemicals. Personnel should be adequately trained, and facilities and precautions as laid down in the relevant safety guidelines in place at the laboratory concerned should be observed.
6.1.2 Sectioning
In many cases, the hard metal sample may have to be sectioned into smaller samples for metallographic preparation. Diamond tooling is normally required to cut hard metals into smaller samples. There is a wide variety of cut-off machines which use blades with diamond embedded on the rim of the disc. Fast cutting times are easily achieved. Wire-cutting machines, in which diamond is embedded in a wire, offer a cheaper method. Very fine slices can be obtained using this method but only at a relatively slow rate of cutting. A faster method is electro-discharge machining, but sufficiently fast machines are not generally suited to a metallographic preparation facility.
6.1.3 Mounting
6.1.3.1 Mounting of the sample into a resin has several advantages: it is more suitable for automatic preparation, the sample is easier to handle, and the specimen codes or identification can be inscribed or written onto the mount. Cold-setting and thermo-setting resins are available.
6.1.3.2 Thermo-setting powders (such as phenolic or diallyl phthalate powders) require a mounting press in which the sample is placed in a chamber, resin is then added, and is melted under pressure. The cycle time for these machines can be quite slow. The advantage is that hazardous chemicals are not used and the resin has an unlimited shelf life.
Foreword I 1 Scope 2 Normative references 3 Terms and definitions 4 Apparatuses 5 Preparation of testpiece section 6 Procedure 7 Test report
Standard
GB/T 33488.1-2017 Test method of pressure equipments of thermoplastics welded for chemicals -- Part 1: General requirements (English Version)
Standard No.
GB/T 33488.1-2017
Status
valid
Language
English
File Format
PDF
Word Count
5500 words
Price(USD)
140.0
Implemented on
2017-9-1
Delivery
via email in 1 business day
Detail of GB/T 33488.1-2017
Standard No.
GB/T 33488.1-2017
English Name
Test method of pressure equipments of thermoplastics welded for chemicals -- Part 1: General requirements
GB/T 33488.1-2017 Hardmetals - Metallographic determination of microstructure Part 1: Photomicrographs and description
1 Scope
This part specifies the methods of metallographic determination of the microstructure of hardmetals using photomicrographs.
2 Normative references
The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.
ISO 3878:1983 Hardmetals - Vickers hardness test
ISO 4499-2 Hardmetals - Metallographic determination of microstructure - Part 2: Measurement of WC grain size
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
α-phase
tungsten carbide
3.2
β-phase
binder phase (for example, based on Co, Ni, Fe)
3.3
γ-phase
carbide having a cubic lattice (for example, TiC, TaC) which may contain other carbides (for example WC) in solid solution
4 Apparatuses
4.1 Metallographic microscope, permitting observations at magnifications up to 1 500 x.
4.2 Scanning electron microscope for magnification over 1 500 x.
4.3 Equipment for preparation of testpiece sections.
5 Preparation of testpiece section
The testpiece section shall be prepared as for metallographic examination,and the surface to be examined shall be free from grinding and polishing marks.Care shall be taken to avoid tearing-out of particles,which may lead to a wrong evaluation of microstructure.
Note: There are several methods for preparation of hard metal surfaces for metallographic examination. Firstly, careful coarse grinding is carried out to remove sufficient material to ensure that the true structure is revealed. After grinding with fine diamond-grit wheels,polishing is effected by using diamond paste or diamond powders,of progressively finer grain size down to 1 μm,on rigidly supported laps of,for example,thin plastic,thin felt or paper.
6 Procedure
6.1 Metallographic preparation
6.1.1 General
6.1.1.1 Good metallographic preparation is essential to produce a plane polished sample that when etched reveals the true microstructure of the hard metal. Bad preparation can lead to grain tear-out, uneven etching and misleading detail in the microstructure which will affect any subsequent measurement.
6.1.1.2 Preparation and etching procedures may require toxic or dangerous chemicals. Personnel should be adequately trained, and facilities and precautions as laid down in the relevant safety guidelines in place at the laboratory concerned should be observed.
6.1.2 Sectioning
In many cases, the hard metal sample may have to be sectioned into smaller samples for metallographic preparation. Diamond tooling is normally required to cut hard metals into smaller samples. There is a wide variety of cut-off machines which use blades with diamond embedded on the rim of the disc. Fast cutting times are easily achieved. Wire-cutting machines, in which diamond is embedded in a wire, offer a cheaper method. Very fine slices can be obtained using this method but only at a relatively slow rate of cutting. A faster method is electro-discharge machining, but sufficiently fast machines are not generally suited to a metallographic preparation facility.
6.1.3 Mounting
6.1.3.1 Mounting of the sample into a resin has several advantages: it is more suitable for automatic preparation, the sample is easier to handle, and the specimen codes or identification can be inscribed or written onto the mount. Cold-setting and thermo-setting resins are available.
6.1.3.2 Thermo-setting powders (such as phenolic or diallyl phthalate powders) require a mounting press in which the sample is placed in a chamber, resin is then added, and is melted under pressure. The cycle time for these machines can be quite slow. The advantage is that hazardous chemicals are not used and the resin has an unlimited shelf life.
Contents of GB/T 33488.1-2017
Foreword I
1 Scope
2 Normative references
3 Terms and definitions
4 Apparatuses
5 Preparation of testpiece section
6 Procedure
7 Test report
