HomeTechnique & ApplicationThe Numbers Of Rockwell Hardness For Steel

The Numbers Of Rockwell Hardness For Steel

These conversions are based on interlaboratory tests conducted on the following grades: Types 201, 202, 301, 302, 304, 304L, 305, 316, 316L, 321, and 347. Tempers ranged from annealed to extra hard for Type 301, with a smaller range of tempers for the other types. Test coupon thicknesses ranged from approximately 0.1 in. (2.5 mm) to 0.050 in. (1.27 mm).

Rockwell Hardness Number Rockwell Superficial Hardness Number
C Scale,150-kgf Diamond Penetrator(HRC) A Scale,60-kgf, Diamond Penetrator(HRA) 15-N Scale,15-kgf,Superficial Diamond Penetrator(HR15N) 30-N Scale,30-kgf,Superficial Diamond Penetrator(HR30N) 45-N Scale,45-kgf, Superficial Diamond Penetrator(HR45N)
48 74.4 84.1 66.2 52.1
47 73.9 83.6 65.3 50.9
46 73.4 83.1 64.5 49.8
45 72.9 82.6 63.6 48.7
44 72.4 82.1 62.7 47.5
43 71.9 81.6 61.8 46.4
42 71.4 81.0 61.0 45.2
41 70.9 80.5 60.1 44.1
40 70.4 80.0 59.2 43.0
39 69.9 79.5 58.4 41.8
38 69.3 79.0 57.5 40.7
37 68.8 78.5 56.6 39.6
36 68.3 78.0 55.7 38.4
35 67.8 77.5 54.9 37.3
34 67.3 77.0 54.0 36.1
33 66.8 76.5 53.1 35.0
32 66.3 75.9 52.3 33.9
31 65.8 75.4 51.4 32.7
30 65.3 74.9 50.5 31.6
29 64.8 74.4 49.6 30.4
28 64.3 73.9 48.8 29.3
27 63.8 73.4 47.9 28.2
26 63.3 72.9 47.0 27.0
25 62.8 72.4 46.2 25.9
24 62.3 71.9 45.3 24.8
23 61.8 71.3 44.4 23.6
22 61.3 70.8 43.5 22.5
21 60.8 70.3 42.7 21.3
20 60.3 69.8 41.8 20.2