Classic oil-hardening tool steel — easy to heat-treat, deeper hardening than plain carbon.
Temper → hardness chart
Approximate HRC after a double-temper at each temperature (from the sources below). Set your target and pick the matching temper.
Temper °F
Temper °C
Hardness
350°F
177°C
62 HRC
400°F
204°C
61 HRC
450°F
232°C
59 HRC
500°F
260°C
57 HRC
Composition (typical, wt%)
Element
%
C
0.95%
Cr
0.5%
V
0.2%
W
0.5%
Mn
1.2%
Si
0.3%
AISI O1 / Uddeholm Arne typical
HeatTreatBench — the recipes in your shop, offline
Get the full O1 recipe plus 25 more steels offline — set your target HRC and the app gives you the exact temper, with a forge timer and a per-blade log. Works in the shop with no signal.