GB/T 7997-2014 in English
VALIDHardmetals―Vickers hardness test
- Issued on:2014-07-24
- Implemented on:2015-02-01
- File Format:PDF
- Delivery:Via email within 1~3 business days
$214.00
《GB/T 7997-2014硬质合金 维氏硬度试验方法》由TC243（全国有色金属标准化技术委员会）归口，TC243SC4（全国有色金属标准化技术委员会粉末冶金分会）执行，主管部门为中国有色金属工业协会。
本标准规定了硬质合金维氏硬度的试验方法。
本标准适用于硬质合金维氏硬度的测定。
Introduction
Analysis of the key points of standard update
| Revised items | GB/T7997-1987 | GB/T7997-2014 |
|---|---|---|
| Test temperature | Not clearly specified | 10-35℃ (Strict test 23±5℃) |
| Rounding of values | According to Appendix C of GB1.1-1981 | Rounded to tenth place according to GB/T8170 |
| Specimen requirements | Surface contaminant requirements are not specified | Prohibition of lubricant residues is added |
Core test requirements
Hardness tester must meet the requirements of GB/T4340.2, with a test force range of 9.807-490.3N (1-50kgf), and 294.2N (30kgf) is recommended. The diamond indenter should maintain an angle of 136°, and the accuracy of the measuring device is graded according to the indentation size:
- d＜100μm: ±0.2μm
- 100-200μm: ±1.0μm
- d≥200μm: ±0.5%
Specimen preparation specifications
Typical preparation process:
- Remove ≥0.2mm surface layer
- Polishing according to GB/T3489
- Ensure sample thickness ≥1μm
- Curved specimens need to be prepared with a flat surface
- Irregular specimens need to be mounted and fixed
Special note: The distance between adjacent indentations should be ≥3 times the average value of the diagonal, and ≥2.5 times the average value from the edge.
Implementation Suggestions
| Common Problems | Solutions |
|---|---|
| Irregular indentation shape | Stop the test immediately and replace the indenter |
| Diagonal difference＞5% | Resample and record abnormalities |
| Large temperature fluctuations | Use a constant temperature laboratory (23±2℃) |
Technology Evolution Analysis
This standard improves the comparability of test results by introducing modern numerical rounding rules (GB/T8170) and clarifying environmental control requirements. Appendix A provides 7 sets of hardness comparison tables (1-50kgf test force) using the new calculation formula: HV=0.102×2F×sin(136°/2)/d², which is more in line with international standards than the 1987 version.
Result report elements
- Standard number GB/T7997-2014
- Specimen identification information
- Average hardness rounded to ten
- Special treatment instructions
- Environmental abnormality records
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