Laminations for copper rotors utilize exactly the same annealing practices as laminations used for aluminum rotors. Information about typical annealing practices is listed in the "Magnetically Soft Materials" section of The Metals Handbook.
Semi-processed grades of electrical steel are delivered in the cold rolled, un-annealed condition, and so must be annealed after stamping to develop suitable magnetic properties. The laminations are typically annealed at temperatures between 790 and 845°C (1450 and 1550°F) for about one hour in a decarburizing atmosphere. The objective of the annealing is to optimize magnetic properties by:
- Eliminating stresses
- Promoting and controlling grain growth
- Further reducing impurities, particularly carbon, nitrogen and sulfur.
Fully processed grades of electrical steel are intended for applications where the laminations can be stamped and placed into service without an additional re-heat treatment. The desirable magnetic characteristics are produced during the manufacturing of the steel, so additional heat treatment by the purchaser is not required. However, after stamping the laminations are typically given a low temperature anneal (at 750-950oC) to remove oils and greases applied during the stamping operation.
Is referencing in this manner enough to get around copyright issue, or do we need to get permission from ASM to use the information from The Metals Handbook.