Interrupted quench in which parts go from austenitizing into a bath held slightly above the Ms temperature, often 150 to 230 °C, stay until surface and core equalize, then cool in air through the martensite range. Because the section transforms nearly all at once, thermal and transformation stresses drop sharply, cutting distortion and cracking. The product is martensite, so the parts still need tempering.
Thin races get marquenched in the 350 oil, a cold-oil dunk turns them into eggs.
Also heard as
- martempering
- marquench
- hot oil quench
Do not mix it up with
- Austempering: Austempering holds long enough to transform the part to bainite, while marquenching takes parts out before transformation so they become martensite.
Related terms
Hot oil
Shop name for quench oil run at about 120 to 230 °C for marquenching and low-distortion quenching.
Ms temperature
The temperature at which martensite starts to form as austenite cools during a quench.
Austempering
Quenching steel into a salt bath above Ms and holding it until the austenite fully transforms to bainite.
Distortion
Unwanted change in shape or size of a part during heat treatment, such as bowing, warping or ovality.