Reference for conversion between Brinell hardness and Rockwell hardness of ordinary ductile iron
1. Comparison of Brinell hardness and Rockwell hardness of QT450-10 and QT450-15
For ductile iron grade 450, when the Brinell hardness is in the range of 160-210HB, if converted to Rockwell hardness, refer to the approximate relationship, it is roughly between HRC20-25 or HRB80-95. However, the actual hardness value may vary depending on the specific composition of the material, heat treatment status and other factors.
2. Brinell hardness and Rockwell hardness of QT500-7
The Brinell hardness of ductile iron QT500-7 is usually in the range of 170-230HB. It can be seen from the hardness conversion table that its Rockwell hardness is roughly between HRC20-30. However, if different heat treatment methods are used, its hardness will be different. For example, after isothermal quenching, the hardness can reach 38-51HRC.
3. Brinell hardness and Rockwell hardness of QT600-3
The Brinell hardness of ductile iron QT600-3 is usually in the range of 190-270HB. According to the hardness conversion table, its Rockwell hardness is roughly between HRA68-82, HRB99-109 or HRC22-32. If it undergoes special heat treatment, such as quenching and tempering, its hardness will be improved. For example, after adopting a suitable quenching process, the hardness may reach about HRC38-51.
4. Brinell hardness and Rockwell hardness of QT700-2
The Brinell hardness of ductile iron QT700-2 is usually in the range of 225-305HB. According to the hardness conversion table, its Rockwell hardness is roughly between HRA74-85, HRB103-113 or HRC25-35.
If special heat treatment is performed, such as induction hardening, the hardness of the wheel rim can reach 50-58HRC.
V. Brinell hardness and Rockwell hardness of QT800-2
The Brinell hardness of ductile iron QT800-2 is usually in the range of 240-310HB. According to the hardness conversion, its Rockwell hardness is roughly between HRA78-88, HRB106-116 or HRC30-35.
If special heat treatment is performed, such as quenching and tempering, its hardness will be improved, and the Rockwell hardness may reach about HRC35-45.
VI. Brinell hardness and Rockwell hardness of QT900-2
The Brinell hardness of ductile iron QT900-2 is usually in the range of 280-360HB. Converted to Rockwell hardness, it is roughly between HRA82-92, HRB109-119 or HRC35-40.
If it undergoes special heat treatment, such as using a suitable quenching and tempering process, its Rockwell hardness may be improved to around HRC40-50.
VII. Metal Rockwell Hardness Testing Scale
Overview
Rockwell hardness is to use a diamond cone with a vertex angle of 120° or a steel ball with a diameter of 1.588mm to press into the surface of the metal material under a certain load, and determine the Rockwell hardness value of the metal by the indentation depth.
Scale
Depending on the hardness of the metal material, different Rockwell hardness scales can be selected, and the commonly used ones are HRA, HRB, and HRC. HRA scale is suitable for high hardness materials, such as cemented carbide, etc., using 588.4N load and diamond cone indenter; HRB scale is suitable for softer metal materials, such as annealed copper alloy, etc., using 980.7N load and 1.588mm diameter steel ball indenter; HRC scale is suitable for medium to high hardness metal materials, such as hardened steel, etc., using 1471N load and diamond cone indenter.
Advantages
Easy operation: The test process is relatively simple and the hardness value can be obtained quickly.
Good repeatability: Under standardized operation, different operators can get relatively consistent results when testing under the same conditions.
Wide range of applications: By selecting different scales, metal materials with various hardness ranges can be measured.
Limitations
High requirements for material surface: The material surface needs to be flat and smooth, otherwise it will affect the measurement accuracy.
Small indentation: For materials with uneven structure, the measurement results may fluctuate greatly due to different indentation positions.
Hardness values cannot be directly converted to other hardness units: there is no exact conversion relationship with Brinell hardness, Vickers hardness, etc., and it can only be approximately converted through empirical formulas or charts.
8. Brinell hardness scale
The Brinell hardness scale is divided into HBS (ordinary steel ball indenter) and HBW (hard alloy indenter). In the Brinell hardness measurement of ductile iron, the HBW scale is usually used because the hard alloy ball indenter is more suitable for measuring ductile iron with higher hardness and can obtain more accurate and reliable results.
The Brinell hardness test requires the selection of appropriate test force F and indenter ball diameter d. For ductile iron, the commonly used test conditions are to use a 10mm diameter hard alloy ball indenter, a test force of 3000kgf (29420N), and the corresponding Brinell hardness scale is HBW10/3000. The indentation area under this test condition is larger, which can reflect the average value of the comprehensive influence of various components in a larger range of ductile iron. It is not affected by individual components and slight unevenness, and can accurately reflect the true hardness of ductile iron.
