Cryo / sub-zeroRequired — dry ice or LN2 to cut retained austenite
Temper2× 2 h · cool to room temp between cycles
Reliable hardness58–62 HRC
High-chromium air-hardening die steel. Plate quench, cryo to convert retained austenite. Low or high temper both used — cross-check your target.
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
300°F
149°C
62 HRC
400°F
204°C
61 HRC
500°F
260°C
60 HRC
600°F
316°C
59 HRC
Composition (typical, wt%)
Element
%
C
1.55%
Cr
11.5%
V
0.8%
Mo
0.9%
Mn
0.35%
AISI D2 / Hudson Tool Steel typical
HeatTreatBench — the recipes in your shop, offline
Get the full D2 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.