WORK HARDEN W012
The metal part becomes hard or brittle by flexing rather than by heat treatment. Austenitic metals become hard this way.
Most of the corrosion resistant stainless steels we use in the seal and pump business are austenitic and this hardening can cause a premature failure with the springs and welded metal bellows we design into mechanical seals.
The hardening can occur during operation of the seal or during the manufacturing process. The hardening can be removed by annealing the piece at a suitable annealing temperature (somewhere below the melting temperature).