Rapid cooling from the austenitizing or solution temperature in water, brine, oil, polymer solution, molten salt or pressurized gas. In steel the goal is to cool faster than the critical rate so austenite becomes martensite; in aluminum and precipitation-hardening alloys it freezes alloying elements in solution. Quench speed is a trade-off: faster means deeper hardening but more distortion and cracking risk.
Pull the rack and quench, ten seconds max from door open to oil.
Ask what a part was quenched in before judging its hardness; the same medium-hardenability steel can read several points apart between still oil and agitated water.
Also heard as
- quenching
- quench hardening
Related terms
Quenchant
The liquid or gas used to quench parts, chosen for its cooling speed and the distortion it produces.
Quench severity
How fast a quenchant pulls heat out of steel, usually rated by the Grossmann H value.
Martensite
The hard, needle-like phase that forms when austenite is quenched fast enough to trap its carbon.
Dunk
Heat-treat slang for quenching a part, especially by hand into an open oil or water tank.
Quench crack
A crack that forms during or soon after quenching from thermal and transformation stress in hardened steel.