Ground Flat Stock - Steel Grades and Processing

Most of the Ground Flat Stock pieces are annealed and ready for machining and heat treatment. (But there are exceptions explained below.) The available tool steel grades are O-1, A-2, A-6, D-2, H-13, M-2, H-13, and S-7. W-1 tool steel is also available but the pieces are cold drawn instead of precision ground.

Stainless steel GFS has the second greatest variety of sizes and steel grades.  The available stainless steels are 410, 420 and 440C. The pieces are annealed and can be hardened by heat treatment. Pre-hardened GFS is 4142 steel. It is not annealed. It is hardened to 26-34 Rc (261-321 Brinell) and has 85% machinability compared to 1.0% carbon steel. Low carbon GFS is C-1018 steel or A-36 steel. It is annealed and stress-relieved. Its hardness is only about 85 Rb (168 Brinell). It can be case hardened.

The Steel Grades Table below shows available the steel grades and how each is processed. To use the table, find the Material type and Steel Grade in the left two columns. Read the manufactures’ conditioning and machining of the pieces in the other columns of the same row.

Material Type Grade Condition Machining
Tool Steel O-1
Annealed Precision Surface Ground
Tool Steel W-1 Annealed Cold Drawn
Stainless Steel 410
Annealed Precision Surface Ground
Pre-Hardened 4142 Through Hardened Precision Surface Ground
Low Carbon C-1018 Annealed and Stress-Relieved Precision Surface Ground