Brinell hardness testing is a common method manufacturers, and engineers use to ascertain the hardness of metal components and materials during the design and manufacturing of these materials. But the tools and equipment available might be for a different test like the Rockwell hardness test. The challenge then becomes getting an equivalent hardness value from a Rockwell hardness value. Consequently, designers and engineers often turn to hardness conversion tables and charts to interpret a hardness value from one hardness testing to the other.
I. What is Rockwell Hardness?
Rockwell hardness testing is a destructive testing method used to determine the tensile strength of a material using an indenter and a set of known loads. The indenter is usually made of steel and can have a ball or conical shape depending on the material tested. Also, depending on the thickness of the material, the load often ranges from 60kg to 150kg. Additionally, the depression caused by the indenter is usually measured and used in a formula to calculate the hardness value of the material. These hardness values can be represented in different scales and converted to values of a different hardness testing method.
Related Article: What are the Advantages and Disadvantages of the Rockwell Method
II. What is Brinell Hardness?
Brinell hardness often requires an indenter ball of hardened steel with a 10mm diameter to cause an indentation on the test material. The weight of this indenter ball is usually 3,000kgf, and it measures the hardness of both soft and hard materials. However, the Brinell hardness test requires an optical instrument like a microscope to determine the indentation on the material caused by the ball indenter.
Related Article: What are the Advantages and Disadvantages of the Brinell Method
III. What is the Difference between Rockwell and Brinell?
Various features differentiate Rockwell and Brinell hardness testing apart. While some are obvious, others are not immediately noticeable and need some digging to identify these differences. These differences include
- Both indenters are different, with a 10mm ball indenter used in Brinell testing and a cone-shaped indenter with a diamond tip for Rockwell testing.
- The hardness values are also different for both hardness testing methods. That’s why a conversion chart is often required to get an equivalent hardness value for the Brinell hardness value when professionals carry out the Rockwell test and vice versa.
- Where the Rockwell test directly measures the indentation on the material, the Brinell test often requires an optical instrument to measure the indentation.
IV. Can you Convert Rockwell to Brinell?
Using a standard formula, it is possible to get equivalent values of Brinell hardness tests from a Rockwell hardness test. This formula also helps to create a conversion table popular in the hardness testing industry for instantly converting between the two hardness tests. However, it is good to note that these conversion formulas and tables only give approximate values but are accurate within tolerable error boundaries.
Related Article: Hardness Test Comparison: Rockwell vs Brinell
Related Article: Rockwell C to Brinell Hardness Conversion Chart
V. How do you Convert HRC to BHN?
Using charts and formulas helps designers and engineers convert the hardness value they get from one hardness test to the required hardness test value. For instance, converting from a Rockwell hardness test on the C scale (HRC) to a Brinell hardness test value requires using the formula: BHN = 5.970 x (HRC + 104.7). This formula gives an approximate value for the Brinell hardness value, and quality assessment professionals use it to create the conversion tables and charts for instant conversion.
VI. Rockwell to Brinell Hardness Conversion Chart
Rockwell Hardness | Brinell Hardness | ||||||
HRA 60kg Brale | HRB 100kg 1/16″ Ball | HRC 150kg Brale | HRD 100kg Brale | HRE 100kg 1/8″ Ball | HRF 60kg 1/16″ Ball | 3,000kg 10mm Steel Ball | 500kg 10mm Steel Ball |
86.5 | — | 70 | 78.5 | — | — | — | — |
86.0 | — | 69 | 77.7 | — | — | — | — |
85.6 | — | 68 | 76.9 | — | — | — | — |
85.0 | — | 67 | 76.1 | — | — | — | — |
84.5 | — | 66 | 75.4 | — | — | — | — |
83.9 | — | 65 | 74.5 | — | — | 739 | — |
83.4 | — | 64 | 73.8 | — | — | 722 | — |
82.8 | — | 63 | 73.0 | — | — | 705 | — |
82.3 | — | 62 | 72.2 | — | — | 688 | — |
81.8 | — | 61 | 71.5 | — | — | 670 | — |
81.2 | — | 60 | 70.7 | — | — | 654 | — |
80.7 | — | 59 | 69.9 | — | — | 634 | — |
80.1 | — | 58 | 69.2 | — | — | 615 | — |
79.6 | — | 57 | 68.5 | — | — | 595 | — |
79.0 | — | 56 | 67.7 | — | — | 577 | — |
78.5 | 120 | 55 | 66.9 | — | — | 560 | — |
78.0 | 120 | 54 | 66.1 | — | — | 543 | — |
77.4 | 119 | 53 | 65.4 | — | — | 525 | — |
76.8 | 119 | 52 | 64.6 | — | — | 500 | — |
76.3 | 118 | 51 | 63.8 | — | — | 487 | — |
75.9 | 117 | 50 | 63.1 | — | — | 475 | — |
75.2 | 117 | 49 | 62.1 | — | — | 464 | — |
74.7 | 116 | 48 | 61.4 | — | — | 451 | — |
74.1 | 116 | 47 | 60.8 | — | — | 442 | — |
73.6 | 115 | 46 | 60.0 | — | — | 432 | — |
73.1 | 115 | 45 | 59.2 | — | — | 421 | — |
72.5 | 114 | 44 | 58.5 | — | — | 409 | — |
72.0 | 113 | 43 | 57.7 | — | — | 400 | — |
71.5 | 113 | 42 | 56.9 | — | — | 390 | — |
70.9 | 112 | 41 | 56.2 | — | — | 381 | — |
70.4 | 112 | 40 | 55.4 | — | — | 371 | — |
69.9 | 111 | 39 | 54.6 | — | — | 362 | — |
69.4 | 110 | 38 | 53.8 | — | — | 353 | — |
68.9 | 110 | 37 | 53.1 | — | — | 344 | — |
68.4 | 109 | 36 | 52.3 | — | — | 336 | — |
67.9 | 109 | 35 | 51.5 | — | — | 327 | — |
67.4 | 108 | 34 | 50.8 | — | — | 319 | — |
66.8 | 108 | 33 | 50.0 | — | — | 311 | — |
66.3 | 107 | 32 | 49.2 | — | — | 301 | — |
65.8 | 106 | 31 | 48.4 | — | — | 294 | — |
65.3 | 105 | 30 | 47.7 | — | — | 286 | — |
64.7 | 104 | 29 | 47.0 | — | — | 279 | — |
64.3 | 104 | 28 | 46.1 | — | — | 271 | — |
63.8 | 103 | 27 | 45.2 | — | — | 264 | — |
63.3 | 103 | 26 | 44.6 | — | — | 258 | — |
62.8 | 102 | 25 | 43.8 | — | — | 253 | — |
62.4 | 101 | 24 | 43.1 | — | — | 247 | — |
62.0 | 100 | 23 | 42.1 | — | — | 240 | 201 |
61.5 | 99 | 22 | 41.6 | — | — | 234 | 195 |
61.0 | 98 | 21 | 40.9 | — | — | 228 | 189 |
60.5 | 97 | 20 | 40.1 | — | — | 222 | 184 |
59.0 | 96 | 18 | — | — | — | 216 | 179 |
58.0 | 95 | 16 | — | — | — | 210 | 175 |
57.5 | 94 | 15 | — | — | — | 205 | 171 |
57.0 | 93 | 13 | — | — | — | 200 | 167 |
56.5 | 92 | 12 | — | — | — | 195 | 163 |
56.0 | 91 | 10 | — | — | — | 190 | 160 |
55.5 | 90 | 9 | — | — | — | 185 | 157 |
55.0 | 89 | 8 | — | — | — | 180 | 154 |
54.0 | 88 | 7 | — | — | — | 176 | 151 |
53.5 | 87 | 6 | — | — | — | 172 | 148 |
53.0 | 86 | 5 | — | — | — | 169 | 145 |
52.5 | 85 | 4 | — | — | — | 165 | 142 |
52.0 | 84 | 3 | — | — | — | 162 | 140 |
51.0 | 83 | 2 | — | — | — | 159 | 137 |
50.5 | 82 | 1 | — | — | — | 156 | 135 |
50.0 | 81 | 0 | — | — | — | 153 | 133 |
49.5 | 80 | — | — | — | — | 150 | 130 |
49.0 | 79 | — | — | — | — | 147 | 128 |
48.5 | 78 | — | — | — | — | 144 | 126 |
48.0 | 77 | — | — | — | — | 141 | 124 |
47.0 | 76 | — | — | — | — | 139 | 122 |
46.5 | 75 | — | — | — | 99.5 | 137 | 120 |
46.0 | 74 | — | — | — | 99.0 | 135 | 118 |
45.5 | 73 | — | — | — | 98.5 | 132 | 116 |
45.0 | 72 | — | — | — | 98.0 | 130 | 114 |
44.5 | 71 | — | — | 100.0 | 97.5 | 127 | 112 |
44.0 | 70 | — | — | 99.5 | 97.0 | 125 | 110 |
43.5 | 69 | — | — | 99.0 | 96.0 | 123 | 109 |
43.0 | 68 | — | — | 98.0 | 95.5 | 121 | 107 |
42.5 | 67 | — | — | 97.5 | 95.0 | 119 | 106 |
42.0 | 66 | — | — | 97.0 | 94.5 | 117 | 104 |
41.8 | 65 | — | — | 96.0 | 94.0 | 116 | 102 |
41.5 | 64 | — | — | 95.5 | 93.5 | 114 | 101 |
41.0 | 63 | — | — | 95.0 | 93.0 | 112 | 99 |
40.5 | 62 | — | — | 94.5 | 92.0 | 110 | 98 |
40.0 | 61 | — | — | 93.5 | 91.5 | 108 | 96 |
39.5 | 60 | — | — | 93.0 | 91.0 | 107 | 95 |
39.0 | 59 | — | — | 92.5 | 90.5 | 106 | 94 |
38.5 | 58 | — | — | 92.0 | 90.0 | 104 | 92 |
38.0 | 57 | — | — | 91.0 | 89.5 | 102 | 91 |
37.8 | 56 | — | — | 90.5 | 89.0 | 101 | 90 |
37.5 | 55 | — | — | 90.0 | 88.0 | 99 | 89 |
37.0 | 54 | — | — | 89.5 | 87.5 | — | 87 |
36.5 | 53 | — | — | 89.0 | 87.0 | — | 86 |
36.0 | 52 | — | — | 88.0 | 86.5 | — | 85 |
35.5 | 51 | — | — | 87.5 | 86.0 | — | 84 |
35.0 | 50 | — | — | 87.0 | 85.5 | — | 83 |
34.8 | 49 | — | — | 86.5 | 85.0 | — | 82 |
34.5 | 48 | — | — | 85.5 | 84.5 | — | 81 |
34.0 | 47 | — | — | 85.0 | 84.0 | — | 80 |
33.5 | 46 | — | — | 84.5 | 83.0 | — | 79 |
33.0 | 45 | — | — | 84.0 | 82.5 | — | 79 |
32.5 | 44 | — | — | 83.5 | 82.0 | — | 78 |
32.0 | 43 | — | — | 82.5 | 81.5 | — | 77 |
31.5 | 42 | — | — | 82.0 | 81.0 | — | 76 |
31.0 | 41 | — | — | 81.5 | 80.5 | — | 75 |
30.8 | 40 | — | — | 81.0 | 79.5 | — | 74 |
30.5 | 39 | — | — | 80.0 | 79.0 | — | 74 |
30.0 | 38 | — | — | 79.5 | 78.5 | — | 73 |
29.5 | 37 | — | — | 79.0 | 78.0 | — | 72 |
29.0 | 36 | — | — | 78.5 | 77.5 | — | 71 |
28.5 | 35 | — | — | 78.0 | 77.0 | — | 71 |
28.0 | 34 | — | — | 77.0 | 76.5 | — | 70 |
27.8 | 33 | — | — | 76.5 | 75.5 | — | 69 |
27.5 | 32 | — | — | 76.0 | 75.0 | — | 68 |
27.0 | 31 | — | — | 75.5 | 74.5 | — | 68 |
26.5 | 30 | — | — | 75.0 | 74.0 | — | 67 |
26.0 | 29 | — | — | 74.0 | 73.5 | — | 66 |
25.5 | 28 | — | — | 73.5 | 73.0 | — | 66 |
25.0 | 27 | — | — | 73.0 | 72.5 | — | 65 |
24.5 | 26 | — | — | 72.5 | 72.0 | — | 65 |
24.2 | 25 | — | — | 72.0 | 71.0 | — | 64 |
24.0 | 24 | — | — | 71.0 | 70.5 | — | 64 |
23.5 | 23 | — | — | 70.5 | 70.0 | — | 63 |
23.0 | 22 | — | — | 70.0 | 69.5 | — | 63 |
22.5 | 21 | — | — | 69.5 | 69.0 | — | 62 |
22.0 | 20 | — | — | 68.5 | 68.5 | — | 62 |
21.5 | 19 | — | — | 68.0 | 68.0 | — | 61 |
21.2 | 18 | — | — | 67.5 | 67.0 | — | 61 |
21.0 | 17 | — | — | 67.0 | 66.5 | — | 60 |
20.5 | 16 | — | — | 66.5 | 66.0 | — | 60 |
20.0 | 15 | — | — | 65.5 | 65.5 | — | 59 |
— | 14 | — | — | 65.0 | 65.0 | — | 59 |
— | 13 | — | — | 64.5 | 64.5 | — | 58 |
— | 12 | — | — | 64.0 | 64.0 | — | 58 |
— | 11 | — | — | 63.5 | 63.5 | — | 57 |
— | 10 | — | — | 62.5 | 63.0 | — | 57 |
— | 9 | — | — | 62.0 | 62.0 | — | 56 |
— | 8 | — | — | 61.5 | 61.5 | — | 56 |
— | 7 | — | — | 61.0 | 61.0 | — | 56 |
— | 6 | — | — | 60.5 | 60.5 | — | 55 |
— | 5 | — | — | 60.0 | 60.0 | — | 55 |
— | 4 | — | — | 59.0 | 59.5 | — | 55 |
— | 3 | — | — | 58.5 | 59.0 | — | 54 |
— | 2 | — | — | 58.0 | 58.0 | — | 54 |
— | 1 | — | — | 57.5 | 57.5 | — | 53 |
— | 0 | — | — | 57.0 | 57.0 | — | 53 |
Conclusion
In conclusion, converting Rockwell hardness to Brinell hardness scale requires a conversion table created using a carefully calculated formula to get an equivalent hardness value. However, you need to know that it is an approximate value with very high accuracy. This conversion will often help when the testing equipment available is one for Rockwell while the required hardness testing scale is a Brinell scale and vice versa.