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.