14
Approximate
Hardness
Conversion
Numbers
for
Non
‐
Austenitic
Steels
(Rockwell
B
Hardness
Range)
A
Rockwell
Superficial
Rockwell
Number
Rockwell B
100kgf
(HRB)
Vickers
(HV)
10‐mm
Standard
ball
3000kgf
(HBS)
Knoop
500‐gf
and
Over
(HK)
A
Scale
60 kgf
(HRA)
F Scale
60kgf
(HRF)
15‐T Scale
15‐kgf
(HR15T)
30‐T Scale
30‐kgf
(HR30T)
45‐T Scale
45‐kgf
(HR45T)
100
99
98
97
96
95
94
93
92
91
90
89
88
87
86
85
84
83
82
81
80
79
78
77
76
75
74
73
72
71
70
69
68
67
66
65
64
63
240
234
228
222
216
210
205
200
195
190
185
180
176
172
169
165
162
159
156
153
150
147
144
141
139
137
135
132
130
127
125
123
121
119
117
116
114
112
240
234
228
222
216
210
205
200
195
190
185
180
176
172
169
165
162
159
156
153
150
147
144
141
139
137
135
132
130
127
125
123
121
119
117
116
114
112
251
246
241
236
231
226
221
216
211
206
201
196
192
188
184
180
176
173
170
167
164
161
158
155
152
150
147
145
143
141
139
137
135
131
129
127
125
124
61.5
60.9
60.2
59.5
58.9
58.3
57.6
57.0
56.4
55.8
55.2
54.6
54.0
53.4
52.8
52.3
51.7
51.1
50.6
50.0
49.5
48.9
48.4
47.9
47.3
46.8
46.3
45.8
45.3
44.8
44.3
43.8
43.3
42.8
42.3
41.8
40.9
40.4
…
…
…
…
…
…
…
…
…
…
…
…
…
…
…
…
…
…
…
…
…
…
…
…
…
99.6
99.1
98.5
98.0
97.4
96.8
96.2
95.6
95.1
94.5
93.9
93.4
92.8
93.1
92.8
92.5
92.1
91.8
91.5
91.2
90.8
90.5
90.2
89.9
89.5
89.2
88.9
88.6
88.2
87.9
87.6
87.3
86.9
86.6
86.3
86.0
85.6
85.3
85.0
84.7
84.3
84.0
83.7
83.4
83.0
82.7
82.4
82.1
81.8
81.4
81.1
83.1
82.5
81.8
81.1
80.4
79.8
79.1
78.4
77.8
77.1
76.4
75.8
75.1
74.4
73.8
73.1
72.4
71.8
71.1
70.4
69.7
69.1
68.4
67.7
67.1
66.4
65.7
65.1
64.4
63.7
63.1
62.4
61.7
61.0
60.4
59.7
59.0
58.4
72.9
71.9
70.9
69.9
68.9
67.9
66.9
65.9
64.8
63.8
62.8
61.8
60.8
59.8
58.8
57.8
56.8
55.8
54.8
53.8
52.8
51.8
50.8
49.8
48.8
47.8
46.8
45.8
44.8
43.8
42.8
41.8
40.8
39.8
38.7
37.7
36.7
35.7