Quench-polish-quench is a multi-step surface treatment sequence used after liquid salt bath nitrocarburizing. The parts are quenched in an oxidizing salt bath, mechanically polished to smooth out surface roughness, and then quenched again in the oxidizing bath. This final step restores the protective black oxide layer removed during polishing, maximizing both lubricity and corrosion resistance.
Heard on the job
The print calls for QPQ on these gun barrels to keep them from rusting in the field.
Also heard as
- quench-polish-quench