GB/T 5168-2020 English PDF (GBT5168-2020)

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GB/T 5168-2020: Microstructure and macrostructure examination for titanium and titanium alloys
GB/T 5168-2020
GB
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
ICS 77.120.50
H 24
Replacing GB/T 5168-2008
Microstructure and macrostructure examination for
titanium and titanium alloys
ISSUED ON: MARCH 06, 2020
IMPLEMENTED ON: FEBRUARY 01, 2021
Issued by: State Administration for Market Regulation;
Standardization Administration of the PRC.
Table of Contents
Foreword ... 3 
1 Scope ... 5 
2 Normative references ... 5 
3 Principle ... 5 
4 Reagents ... 5 
5 Apparatus ... 6 
6 Macrostructure examination ... 6 
7 Microstructure examination ... 8 
8 Determination of common defect structures of titanium and titanium alloys 11 
9 Test report ... 13 
Appendix A (Informative) Metallographs of typical macrostructures and
microstructures of titanium and titanium alloys ... 14 
Appendix B (Informative) Metallographs of typical metallurgical defects of
titanium and titanium alloys ... 21 
Appendix C (Informative) Metallographs of typical processing defects of
titanium and titanium alloys ... 24 
Appendix D (Informative) Metallographs of typical heterogeneous structures of
titanium and titanium alloys ... 30 
Appendix E (Normative) Method for measuring the content of primary α-phase
... 33 
Appendix F (Normative) Method for measuring the size of strip α-phase ... 38 
Foreword
This Standard is drafted in accordance with the rules given in GB/T 1.1-2009.
This Standard replaces GB/T 5168-2008 "Microstructure and macrostructure
examination for α-β titanium alloys".
Compared with GB/T 5168-2008, in addition to editorial changes, the main
technical changes of this Standard are as follows:
- ADD the elements "Principle", "Reagents", and "Apparatus" (see Clause 3,
Clause 4, and Clause 5);
- Modify the requirements for preparation of macrostructure sample (see 6.1;
2.1 of the 2008 edition);
- ADD the requirements for heat treatment of samples during macro-β-spot
and macro-grain size examination (see 6.2.2);
- Modify the composition of macrostructure corrosive agent (see Table 2;
2.2.1 of the 2008 edition);
- Modify the requirements for preparation of microstructure sample (see 7.2;
3.1 of the 2008 edition);
- Modify the composition of microstructure corrosive agent (see Table 3; 3.1.3
of the 2008 edition);
- ADD "Determination of common defect structures" (see Clause 8);
- ADD "Metallographs of typical macrostructures and microstructures of
titanium and titanium alloys"; delete Appendix A the 2008 edition "Personal
and apparatus protection" (see Appendix A; Appendix A of the 2008 edition);
- Modify the content of Appendix B; CHANGE from "Typical pictures of
macrostructures" to "Metallographs of typical metallurgical defects of
titanium and titanium alloys" (see Appendix B; Appendix B of the 2008
edition);
- Modify the content of Appendix C; CHANGE from "Typical pictures of
microstructures" to "Metallographs of typical processing defects of titanium
and titanium alloys" (see Appendix C; Appendix C of the 2008 edition);
- ADD Appendix D "Metallographs of typical heterogeneous structures of
titanium and titanium alloys" (see Appendix D);
Microstructure and macrostructure examination for
titanium and titanium alloys
1 Scope
This Standard specifies the microstructure and macrostructure examination for
α-type, α-β-type, β-type titanium and titanium alloys.
This Standard applies to the microstructure and macrostructure examination for
titanium and titanium alloys.
2 Normative references
The following documents are indispensable for the application of this document.
For the dated references, only the editions with the dates indicated are
applicable to this document. For the undated references, the latest edition
(including all the amendments) are applicable to this document.
GB/T 6394 Metal - Methods for estimating the average grain size
GB/T 6611 Terminology and metallographs for titanium and titanium alloys
GB/T 13298 Inspection methods of microstructure for metals
YB/T 4377 Electrolytic polishing method of metallic specimens
3 Principle
Low magnification (macrostructure) examination is to select the appropriate
corrosive agent to show the macrostructure of titanium and titanium alloy
samples; use a magnifying glass no more than 20 times or visually check the
morphological characteristics. High magnification (microstructure) examination
is to select the appropriate corrosive agent to reveal the microstructure of
titanium and titanium alloy samples; use the microscope to analyze and identify
the microstructure characteristics of titanium and titanium alloy materials.
4 Reagents
Unless otherwise stated, the reagents used in the test are chemically pure.
4.1 Ammonium bifluoride (ρ=1.52 g/cm3).
4.2 Hydrofluoric acid (ρ=1.15 g/mL).
4.3 Nitric acid (ρ=1.40 g/mL).
4.4 Hydrochloric acid (ρ=1.19 g/mL).
4.5 Hydrogen peroxide (ρ=1.10 g/mL).
4.6 Glacial acetic acid (ρ=1.05 g/mL).
4.7 Glycerol (glycerin) (ρ=1.3 g/mL).
5 Apparatus
5.1 Microstructure and macrostructure examination related equipment includes
sample preparation equipment (metallographic cutting machine, inlay machine,
grinding-polishing machine, electrolytic polishing corrosion equipment, etc.),
metallographic microscope, and photographic system, etc. It shall all meet the
relevant safety and technical requirements.
5.2 The metallographic grinding-polishing machine shall be equipped with water
inlet and drainage channels; or select fully-automatic sample preparation
equipment.
5.3 The metallographic microscope shall be qualified by measurement
calibration. The photographic system shall ensure the traceability of the image
size. If there is a scale in the eyepiece, the micrometer shall be used for
calibration. The micrometer shall be subject to verification according to the
measurement requirements.
6 Macrostructure examination
6.1 Sampling
6.1.1 Macrostructure samples shall be cut according to product technical
requirements or the provisions of Table 1.
6.1.2 During the sample cutting process, appropriate measures shall be taken,
to avoid changes in the sample surface and internal tissues.
7.1.1 According to product technical requirements or test purposes, samples
shall be cut from representative locations or samples that have undergone
macrostructure examination. During the cutting process, plastic deformation
and microstructure changes caused by heat shall be prevented.
7.1.2 Recommended sample size: The area of the surface to be examined is
less than 400 mm2. The height is preferably 15 mm~20 mm.
7.1.3 According to different examination purposes, select a reasonable surface
to be examined and clearly mark. Longitudinal section is selected for the
surface to be examined of the structure of extruded or rolled pipe. Transverse
section, which is perpendicular to the main deformation direction, is selected
for the surface to be examined of the structure of other processed products.
7.2 Sample inlay
7.2.1 When checking the surface structure of processed products, or when the
sample is small, irregular in shape, porous, etc., the sample shall be inlaid.
7.2.2 Inlay methods include hot inlay, cold inlay, and mechanical clamping,
which can be selected according to the sample and examination requirements.
For specific operations, see GB/T 13298.
7.3 Sample grinding
7.3.1 Choose sandpaper or millstones with different grain sizes from coarse to
fine;...