GB/T 42670-2023
Method for determination of Rockwell hardness of carbon materials (English Version)
- Standard No.
- GB/T 42670-2023
- Language
- Chinese, Available in English version
- Release Date
- 2023
- Published By
- General Administration of Quality Supervision, Inspection and Quarantine of the People‘s Republic of China
- Latest
- GB/T 42670-2023
- Scope
- This document describes the principle, instrumentation, specimens, test procedures, precision and test report of the Rockwell hardness test method for carbon materials. This document is applicable to the determination of the Rockwell hardness of carbon materials with aggregate particles less than 0.8mm, and is used as a reference for other carbon materials.
- Introduction
1. Background and significance of the standard
GB/T 42670—2023 "Method for determination of Rockwell hardness of carbon materials" is an important standard for hardness testing of carbon materials. This standard specifies the principle, instrumentation, specimen preparation and test steps of Rockwell hardness determination, and is applicable to carbon materials with aggregate particles less than $0.8\mathrm{mm}$.
2. Principle of Rockwell hardness determination
The Rockwell hardness test characterizes the hardness of a material based on the change in indentation depth. The initial test force and the main test force are applied by a standard indenter, the residual indentation depth is measured, and the hardness value is calculated according to the formula:
$$ \mathrm{HR}=Nh/S $$Wherein, $N$ and $S$ are the full range constant and scale constant.
3. Instrument and Indenter Selection
Rockwell Hardness Scale Symbol Unit Indenter Type Initial Test Force $F_0$ Total Test Force $F$ Scale Constant $S$ Applicable Range A HRA Diamond Cone Indenter 588.4 N 20HRA~95HRA 100 20HRA~95HRA B HRBW Φ1.5875mm ball indenter 980.7 N 10HRBW~100HRBW 130 Note: Different scales are suitable for different material hardness ranges. The specific selection should be determined according to actual needs.
4. Specimen preparation requirements
- Specimen thickness: The recommended size is $\phi35~\mathrm{mm}\times30~\mathrm{mm}$.
- Parallelism deviation: not more than $0.10\mathrm{mm}/100\mathrm{mm}$.
- Surface roughness: $R a\leqslant3.2\mu\mathrm{m}$.
5. Experimental steps and precautions
Before the test, ensure that the equipment is calibrated and the indenter is free of rust or scratches. During the test, the measurement should be repeated at least 5 times and the average value should be taken.
Note:The center distance between two adjacent indentations should be greater than the indenter diameter to avoid interference.
6. Implementation suggestions
To ensure the accuracy of the test, it is recommended that:
- Strictly calibrate the equipment according to the standard.
- Choose an appropriate Rockwell hardness scale.
- Record the test conditions and result deviations.
GB/T 42670-2023 Referenced Document
- GB/T 1427 Sample method of carbon material
- GB/T 230.2 Metallic materials—Rockwell hardness test—Part 2: Verification and calibration of testing machines and indenters
- GB/T 8170 Rules of rounding off for numerical values & expression and judgement of limiting values
- JJG 112 Metallic Rockwell Hardness Testing Machines (Scales A, B, C, D, E, F, G, H, K, N, T)
- JJG 884 Verification Regulation of Plastic Rockwell Hardness Testing Machine
GB/T 42670-2023 history
- 2023 GB/T 42670-2023 Method for determination of Rockwell hardness of carbon materials