Ground Flat Stock - Hardness and Machinability

The tool steels (O-1, A-2, D-2, H-13, S-7, and W-1) are annealed. The tools steels can be hardened with the appropriate heat treatment methods. The steel (4142) GFS is pre-hardened and can be machined with conventional tooling. The low carbon steel (C-1018) and the stainless steels (410, 420, and 440C) GFS are also ready for machining. The low carbon steel can be case hardened if desired.

The Ground Flat Stock Hardness and Machinability Table below lists the hardness and machinability of available steel grades. To use the table, find the Material type and Steel Grade in the left two columns. Read the hardness and machinability in the other columns of the same row.

Material Type Grade Brinell Hardness Rockwell Hardness Machinability *
Tool Steel(Annealed) O-1 177-212 88-95 Rb 95%
A-2 200-235 93-99 Rb 65%
D-2 220-255 97-102 Rb 50%
H-13 230 98 Rb 75%
S-7 188-223 90-97 Rb 95%
W-1 200 93 Rb 100%
Pre-hardened 4142 261-321 26-34 Rc 85%
Stainless Steel 410 217 96 Rb 54%
420 255 25 Rc 45%
440C 229-269 21-28 Rc 45%
Low Carbon C-1018 168 85 Rb 78%

* Compared to 1.0% carbon steel.