Metal finishing Q&As since 1989

-----

Minimum magnetic annealing temperature for 316 stainless steel.

We turn S/S components up to 10 kg from 316 bar stock and polish these to a mirror finish. We need to achieve a very low magnetic susceptibility for the finished product of <0.02. The turning process increases the mag sus due to work hardening so we have tried vacuum annealing the turned product prior to polishing and this works well but the annealing often results in very small pit marks showing up in the polishing. These appear to be harder than the surrounding material as small drag marks appear around these areas when polishing. Is there a minimum temperature we can use that will reduce the magnetic susceptibility but not change the material so we can avoid the pit marks?
Our only other option is to use 904 grade but the cost is significantly higher.

Paul Copeland
Manufacturer - Melbourne Australia
October 5, 2011