Cryo / sub-zeroOptional — dry ice recommended for stability
Temper2× 2 h · cool to room temp between cycles
Reliable hardness57–62 HRC
Air-hardening tool steel — preheat at 1450°F, plate-quench to stay flat. Cryo trims retained austenite.
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
60 HRC
500°F
260°C
58 HRC
600°F
316°C
57 HRC
Composition (typical, wt%)
Element
%
C
1%
Cr
5.25%
V
0.25%
Mo
1.1%
Mn
0.7%
Si
0.3%
AISI A2 typical
HeatTreatBench — the recipes in your shop, offline
Get the full A2 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.