HARDNESS CRUSH LOAD

Hardness and Crushing Load

SIZE CHROME STEEL BALL CARBON STEEL BALL
inch mm Surface Hardness Crushing Load Surface Hardness Crushing Load
(Kg)		 Case Depth
(mm)
0.5 HV760
~
HV880		 Minimum Crush Load ≧ D1.73〔KN〕 HV760
~
HV880		 0.1
1/32” 0.794
1.0
1/16” 1.588 170 0.4
2.0 250
3/32” 2.381 300 0.5
2.5
3.0
1/8” 3.175 HRC60
~
HRC66		 HRC60
~
HRC66		 500 0.6
5/32” 3.969 800
4.0 --
3/16” 4.762 1100 0.8
5.0 1100
7/32” 5.556 1200 0.9
6.0 1200
1/4” 6.350 1600 1.1
5/16” 7.938 2400
3/8” 9.525 3000 1.4
7/16” 11.112 3500 1.7
1/2” 12.7 4500 1.8
5/8” 15.875 1.9
3/4” 19.050 2.0
7/8” 22.225
1” 25.4

Table 1: Hardness Correction Table

Correction to be added to rockwell "C" readings obtained on spherical surfaces.

Sphercial
Surface
Hardness (Ho)		 Ball Diameter (Metric Sizes)
4mm
(ΔH)		 5mm
(ΔH)		 6mm
(ΔH)		 7mm
(ΔH)		 8mm
(ΔH)		 9mm
(ΔH)		 10mm
(ΔH)
51 6.85 5.48 4.56 3.91 3.42 3.04 2.74
53 6.60 5.28 4.40 3.77 3.30 2.93 2.64
54 6.47 5.18 4.32 3.70 3.24 2.88 2.59
55 6.35 5.08 4.23 3.63 3.18 2.82 2.54
56 6.23 4.99 4.15 3.56 3.12 2.77 2.49
57 6.11 4.89 4.08 3.49 3.06 2.72 2.45
58 5.99 4.80 4.00 3.43 3.00 2.66 2.40
59 5.88 4.70 3.92 3.36 2.94 2.61 2.35
60 5.76 4.61 3.84 3.29 2.88 2.56 2.30

Flat Surface Hardness (H) = Spherical Surface Hardness (Ho) + ΔH

Sphercial
Surface
Hardness (Ho)		 Ball Diameter (Inch Sizes)
1/8”
(ΔH)		 5/32”
(ΔH)		 3/16”
(ΔH)		 7/32”
(ΔH)		 1/4”
(ΔH)		 9/32”
(ΔH)		 5/16”
(ΔH)
51 8.6 6.90 5.75 4.93 4.31 3.83 3.45
52 8.5 6.77 5.64 4.84 4.23 3.76 3.39
53 8.3 6.65 5.54 4.75 4.16 3.69 3.32
54 8.2 6.52 5.44 4.66 4.08 3.62 3.26
55 8.0 6.40 5.34 4.57 4.00 3.56 3.20
56 7.9 6.28 5.23 4.49 3.93 3.49 3.14
57 7.7 6.16 5.13 4.40 3.85 3.42 3.08
58 7.6 6.04 5.03 4.32 3.78 3.36 3.02
59 7.4 5.92 4.94 4.23 3.70 3.29 2.96
60 7.3 5.81 4.84 4.15 3.63 3.23 2.90