Brinell hardness calculator
Brinell hardness from HB = 2F / (π D (D − √(D² − d²))) per GB/T 231.1 and ISO 6506, with the indentation area, the 0.102F/D² test condition and a check that d/D falls inside the valid 0.24–0.6 window.
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Hardness result
Computed per GB/T 231.1 and ISO 6506.
Enter the indentation diameter to calculate Brinell hardness
Brinell hardness: 0 · Indentation area: 0 · Test condition: 0
What this tool does
- Convert a bench reading: the tester reports the indentation diameter, this formula turns it into HBW.
- Cross-check a lab report by back-computing the indentation diameter from the quoted HBW.
- Decide whether a test is valid: d/D must sit between 0.24 and 0.6 or the standard says to repeat it.
Example
Input
3.5
Output
布氏硬度：100.65087 HBW 压痕面积 A = πD(D − √(D² − d²))：19.870668 mm² 公式 HB = 2F / (π D (D − √(D² − d²)))：2 × 1000 ÷ (π × 10 × 0.632503) = 100.65087 试验力：1000 kgf = 9806.65 N 试验条件 0.102F/D²：1.02 → 非标准条件 压痕直径比 d/D：0.35（在 0.24–0.6 的有效区间内）
D10 at 3000 kgf with a 4.2 mm indentation gives 206.525 HBW, typical for quenched and tempered steel.
Frequently asked questions
Is F in kilograms-force or newtons?
Kilograms-force. GB/T 231.1 and ISO 6506 define Brinell hardness with F in kgf, where 3000 kgf is about 29420 N. The tool accepts N as well and divides by 9.80665 first.
What is the valid range for d?
The standard requires d between 0.24D and 0.6D, roughly 650 HBW down to 30 HBW. Outside that the indentation is too small (too hard or too little force) or too large (too soft) and the result is not comparable — change the test force.
What is the difference between HBW and HBS?
The indenter material: HBW uses a tungsten carbide ball, HBS a hardened steel ball. ISO 6506 dropped the steel ball in 2005, so modern reports should all read HBW.
What does the 0.102F/D² condition mean?
It is the similarity principle: as long as 0.102F/D² is the same, different ball diameters give the same hardness on the same material. Steel uses 30, copper and aluminium 10, soft metals 5, bearing alloys 2.5.
Why is there no HRC conversion?
There is no exact analytical link between Brinell and Rockwell — only tables and empirical fits that vary by material. Use a dedicated conversion tool rather than a plausible-looking number.
Keywords：布氏硬度Brinell hardnessHBW压痕直径硬度换算GB/T 231.1球压痕材料检测