Reprocessing a lot that came out soft from a slack quench, the wrong recipe or over-tempering. Parts are normally normalized or annealed first to erase the old structure, then austenitized and quenched again. Each rehard adds decarb, distortion and grain growth risk, and many aerospace and automotive specs limit or forbid it without customer approval.
Lot's three points soft from the bad quench, normalize and rehard, and write it up as rework.
Also heard as
- reharden
- re-harden
Related terms
Slack quench
A quench too slow to make full martensite, leaving pearlite, bainite or ferrite and low hardness.
Normalizing
Heating steel above its upper critical temperature and cooling it in still air to refine and even out grain.
Points
Shop shorthand for Rockwell numbers, as in a part running two points high on hardness.
Decarburization
Loss of carbon from the surface of steel during heating, leaving a soft skin that will not fully harden.