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Hardness conversion table cross-referencing Rockwell C (HRC), Brinell (HB 10/3000), Vickers (HV), and approximate tensile strength in MPa for carbon and alloy steels. Hardness Conversion Chart Values are per ASTM E140 and ISO 18265. Brinell values above HRC 40 are generally not reliable because the test ball deforms, so those cells are left blank. Tensile strength conversions above HRC 52 are outside the validated range and are omitted.
HRC |
HB (Brinell) |
HV (Vickers) |
Approx. Tensile Strength (MPa) |
|---|
68 |
- |
940 |
- |
67 |
- |
900 |
- |
66 |
- |
865 |
- |
65 |
- |
832 |
- |
64 |
- |
800 |
- |
63 |
- |
772 |
- |
62 |
- |
746 |
- |
61 |
- |
720 |
- |
60 |
- |
697 |
- |
59 |
- |
674 |
- |
58 |
- |
653 |
- |
57 |
- |
633 |
- |
56 |
- |
613 |
- |
55 |
- |
595 |
- |
54 |
- |
577 |
- |
53 |
- |
560 |
- |
52 |
- |
544 |
2180 |
51 |
- |
528 |
2110 |
50 |
- |
513 |
2050 |
49 |
- |
498 |
1990 |
48 |
- |
484 |
1930 |
47 |
- |
471 |
1870 |
46 |
- |
458 |
1820 |
45 |
- |
446 |
1760 |
44 |
- |
434 |
1710 |
43 |
- |
423 |
1660 |
42 |
- |
412 |
1610 |
41 |
- |
402 |
1560 |
40 |
371 |
392 |
1510 |
39 |
362 |
382 |
1460 |
38 |
353 |
372 |
1420 |
37 |
344 |
363 |
1370 |
36 |
336 |
354 |
1330 |
35 |
327 |
345 |
1290 |
34 |
319 |
336 |
1250 |
33 |
311 |
327 |
1210 |
32 |
301 |
318 |
1170 |
31 |
294 |
310 |
1140 |
30 |
286 |
302 |
1110 |
29 |
279 |
294 |
1080 |
28 |
271 |
286 |
1050 |
27 |
264 |
279 |
1020 |
26 |
258 |
272 |
990 |
25 |
253 |
266 |
970 |
24 |
247 |
260 |
950 |
23 |
243 |
254 |
930 |
22 |
237 |
248 |
910 |
21 |
231 |
243 |
880 |
20 |
226 |
238 |
860 |
How to use the hardness conversion chart
Find your known hardness value in the appropriate column and read across for the equivalent in other scales. These conversions are approximate - they're based on statistical correlations for carbon and alloy steels, not exact mathematical relationships. For austenitic stainless steels, non-ferrous metals, or case-hardened surfaces, use dedicated conversion tables for those materials.
Rockwell C (HRC) is the standard scale for hardened steels (typically 20-68 HRC). Brinell (HB) is common for softer steels and castings (typically 100-450 HB). Vickers (HV) covers the full range and is useful for thin sections and surface hardness testing because it uses a smaller indentation.
Tensile strength conversion is the least accurate column. It's useful for rough estimates but shouldn't replace actual tensile testing when strength values are needed for design calculations.
Related standards
- ASTM E140 - Standard hardness conversion tables for metals
- ISO 18265 - Metallic materials: hardness conversion tables
- ISO 6506 - Metallic materials: Brinell hardness test
- ISO 6507 - Metallic materials: Vickers hardness test
- ISO 6508 - Metallic materials: Rockwell hardness test
- BS EN ISO 6508-1 - UK adoption of Rockwell hardness test
Hardness testing equipment
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Frequently Asked Questions
What HRC is equivalent to 300 HB Brinell?
300 HB Brinell is approximately equivalent to 32 HRC Rockwell C (with an HV Vickers value of around 318). The approximate tensile strength at this hardness is 1170 MPa. These conversions are per ASTM E140 for carbon and alloy steels.
Can I convert hardness to tensile strength?
Yes, but only approximately. Hardness-to-tensile-strength conversion is an empirical correlation, not an exact relationship. It works reasonably well for plain carbon and low-alloy steels in the range of about 20-52 HRC. For other materials or heat treatment conditions, the correlation may not hold. Always test tensile strength directly for critical applications.
Why are some Brinell values blank in the conversion chart?
Above about 40 HRC (371 HB), the Brinell test ball starts to deform, making the results unreliable. The standard Brinell test uses a 10mm tungsten carbide ball with 3000 kgf load, and at high hardness the ball flattens. For hardened steels above 40 HRC, use Rockwell C or Vickers instead.
What is the Hardness Conversion Chart primarily used for?
The Hardness Conversion Chart is a reference tool that cross-references Rockwell C (HRC), Brinell (HB 10/3000), and Vickers (HV) hardness scales, providing approximate tensile strength in MPa for carbon and alloy steels. It adheres to standards ASTM E140 and ISO 18265.
Why are Brinell values above HRC 40 unreliable according to the Hardness Conversion Chart?
Brinell hardness values above HRC 40 are generally not reliable because the test ball deforms under higher pressures, leading to inaccurate readings. As a result, these cells are left blank in the chart.
How does one select an appropriate scale for measuring hardness using the Hardness Conversion Chart?
The selection of a hardness measurement scale depends on the material's properties and the required precision. For instance, Vickers is suitable for thin or small parts due to its wide range of applicability from soft metals to extremely hard materials.
Which standards does the Hardness Conversion Chart follow?
The chart adheres to ASTM E140 and ISO 18265 standards, providing a scientifically validated method for hardness conversion among Rockwell C (HRC), Brinell (HB 10/3000), Vickers (HV), and approximate tensile strength in MPa.
Can you recommend any UK suppliers for obtaining Hardness Conversion Chart materials?
British companies like Bowers硬度转换图表供应商信息似乎没有直接提供在给定的页面内容中。不过，英国的一些知名金属处理和测试设备公司通常会提供此类图表或相关服务。
What is the cost and availability of the Hardness Conversion Chart for UK engineers?
The Hardness Conversion Chart itself, as a reference tool on websites like mlc.org.uk, is typically free to access online. Physical copies or specialized software might have costs associated with them from suppliers.
How does the Hardness Conversion Chart handle tensile strength conversions above HRC 52?
Tensile strength conversions for hardness values above HRC 52 are outside the validated range according to ASTM E140 and ISO 18265 standards, so these values are omitted from the chart.