This should be confirmation of hardness = darkness FOR NON-ALLOY steel

Rockwell Hardness
Grey Cast Iron - 63
Wrought Iron - 65
AISI 1020 - 68
AISI 1030 - 80
AISI 1040 - 93

Brinell
Grey Cast Iron - 100
Wrought Iron
1020 - 121
1030 - 149
1040 - 201

Last edited by Drew Hause; 03/02/16 08:55 AM. Reason: Brinell numbers added