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Heat treatment — Jominy hardenability

End-quench hardenability curve · ASTM A255

Compare alloy steels' through-hardening capability. The Jominy test ranks hardenability by hardness vs distance from a quenched end.

Inputs

HRC
At the quenched end, ~maximum hardness possible for this carbon level
HRC
Standard Jominy reference distance · indicates deep hardenability
mm
Distance into the section where you need the target hardness
HRC
mm
If specified, computes equivalent Jominy distance at the bar centre (Grossmann ≈ 0.4·D)
workhorse machine-shaft alloy

Results

Jominy hardenability curve · ASTM A255
target 45 HRCJ = 16mm01020304050203040506070Jominy distance J (mm from quenched end)Hardness (HRC)ASTM A255 · single-bar end-quench · τ ≈ 14 mm exponential approximation
H_RC at J=0: 60 · J=32mm: 35 · @ target J=16mm: 43.0 → WARN — within 3 HRC of target
Bar centre equivalent J (Grossmann ≈ 0.4·D)20mm
Higher J32 = deeper hardenability (4340 = deep, 1040 = shallow). Pick the alloy whose Jominy curve passes above the target HRC at your target depth. For oil quench at large sections (D > 50 mm) you typically need 4140 or better.
Download all inputs + calculations + outputs as a single PDF.