JB/T 7946.3-2017Metallography of cast aluminium alloys - Part 3: Pinholes in cast aluminium alloys (English PDF)
铸造铝合金金相 第3部分：铸造铝合金针孔
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Issued by
MIIT
Level / Type
Industry · Recommended
Issue date
January 9, 2017
Implementation date
July 1, 2017
Scope
JB/T 7946.3-2017 is the English-translated version of 铸造铝合金金相 第3部分：铸造铝合金针孔.
Pinholes in cast aluminium alloys are the subject of part 3 of JB/T 7946 on the metallographic examination of cast aluminium alloys. JB/T 7946.3-2017 gives terms and definitions, the cutting and preparation of the specimen, and the test methods together with the assessment of the results.
It applies to the evaluation of the pinhole of cast aluminium alloys. The part replaces JB/T 7946.3-1999; it was issued on 9 January 2017 and implemented on 1 July 2017.
It was registered under number 57829-2017 and issued by the Ministry of Industry and Information Technology.
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Document preview — JB/T 7946.3-2017
National Standard of the People's Republic of China
- Replacing
- JB/T 7946.3-1999
Issued by: Ministry of Industry and Information Technology of the People's Republic of China
Contents
- Foreword3
- 1 Scope4
- 2 Normative references4
- 3 Terms and definitions4
- 4 Cutting and preparation of specimen4
- 4.1 Cutting of specimen4
- 4.2 Preparation of specimen5
- 5 Test methods and results assessment5
1 Scope
This part of JB/T 7946 specifies the terms and definitions, the cutting and preparation of the specimens, the test methods and the evaluation of the results of the pinholes of cast aluminum alloys.
This part applies to the evaluation of the pinhole of cast aluminum alloys.
2 Normative references
The following documents are indispensable for the application of this document.
For dated references, only the dated version applies to this document. For undated references, the latest edition (including all amendments) applies to this document.
GB/T 5611 Foundry terminology
3 Terms and definitions
The terms and definitions as defined in GB/T 5611 as well as the following terms and definitions apply to this document.
3.1 Pinhole degree
Indicates the pinhole's severity level.
Note: Judging according to the number and diameter of pinholes in the range of 1 cm² on the surface of the sample.
4 Cutting and preparation of specimen
4.1 Cutting of specimen
The metallographic specimen is usually taken from the thick part where the casting is solidified slowly, it may also be cut out from the designated part of the casting according to the technical documents.
4.2 Preparation of specimen
4.2.1 The surface of the specimen can be machined or polished on 400# ~ 600# sandpaper. The surface roughness Ra is not more than 1.6 µm.
4.2.2 The surface of the specimen shall be free from dirt or impurities. If present, the surface of the specimen shall be treated by the use of alcohol, acetone or gasoline.
4.2.3 The surface of the machined specimen can be directly judged by the level of pinhole. It is also possible to chemically corrode the surface of the specimen and then measure the pinhole level after polishing. After polishing, at room temperature, use the 10% ~ 15% (mass fraction) aqueous sodium hydroxide solution to corrode the surface of the specimen, until a black film is formed on the surface to be inspected. The ratio of the amount of corrosive agent to the volume of the immersed part of the specimen shall be not less than 10. For corrosive agents that have been used for a long time, it shall appropriately extend the corrosion time and replace the new corrosive agents regularly.
4.2.4 After corrosion, first use water to rinse the specimen. Then use a 20% ~ 25% (mass fraction) aqueous solution of nitric acid to remove the black film on the surface. Use water to rinse it again. Dry it.
5 Test methods and results assessment
5.1 It shall assess the pinhole of the surface to be inspected under conditions of good illumination. Depending on the quality of the machining, the optimum illumination angle shall be 10° ~ 15° with respect to the direction opposite to the inspection direction. It shall not assess the surface under scattered lighting conditions.
5.2 Use a magnifying glass which has a magnification of not more than 10 times for inspection (only when measuring the diameter of the pinhole). Define a 10 mm × 10 mm area in the most-dense area of the pinholes, check the number and diameter of the pinholes.
5.3 According to the test results, according to the grading standard, determine the pinhole degree. The description of grading is as shown in Table 1.
5.4 The pinhole degree is determined according to the grading criteria listed in Table 1. Use the worst degree of sampling as the test result. […]
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This preview omits tables, figures, formulas and parts of the technical clauses. The complete document — 15 pages — is available in the English PDF.
Referenced standards
Normative references
Cited by
- QC/T 1223-2025Special requirements for the heavy commercial vehicle and combination vehicles fitted with lift axle
- QC/T 272-2025Technical specifications of aluminum alloy castings for automobiles
- GB/T 23301-2024Cast aluminium alloys for automobile wheels
- GB/T 16746-2018Zinc alloy castings
- GB/T 9438-2013Aluminum alloy castings
- GB/T 29434-2012Aluminum alloy ingots for high strength and toughness castings with heat resisting
Similar standards
Editions of JB/T 7946.3
| Edition | Title | Revision | Status |
|---|---|---|---|
| JB/T 7946.3-2017 | Metallography of cast aluminium alloys - Part 3: Pinholes in cast aluminium alloys | current edition | Current |
| JB/T 7946.3-1999 | Metallography of cast aluminium alloys - Part 3: Pinholes in cast aluminium alloys | previous edition | Superseded |
This page sells the current edition, JB/T 7946.3-2017. Earlier editions are listed for reference only.
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Related Standards
GB/T 5611-2017 — Foundry terminology
JB/T 7946.4-2017 — Metallography of cast aluminium alloys - Part 4: Grain size of cast aluminium-copper alloys
JB/T 7946.2-1999 — Metallography of cast aluminium alloys - Overheating of cast aluminium-silicon alloys
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