Critical reduction in rolling of dynamo sheet

Summary

• 1. Dynamo steel has a critical deformation range equivalent to a relative reduction of 2–8%. After critical reductions, dynamo steel is coarse-grained (20–90 grains per sq. mm) and therefore its specific watt losses are 10 to 14% lower [than without such treatment].

• 2. Some reduction of magnetic induction in strong fields after critical reductions (averaging 2%) is compensated by an increase of the space factor of the steel from 88–90% for hot rolled sheet to 96–97% after critical reductions.

• 3. There is no technical difficulty in applying critical reductions to dynamo steel and they can be recommended for improving its service properties.