Effect of copper precipitates on the stability of microstructures and magnetic properties of non-oriented electrical steels

• Small quantities of copper were added to non-oriented electrical steels.
• A metastable Cu-rich phase precipitated in hot-rolled bands.
• These precipitates can increase the microstructure stability of the steel.
• These precipitates can also increase the stability of magnetic properties.
• The microstructure and magnetic properties can be controlled by these precipitates.

Non-oriented electrical steels with different amounts of copper were prepared and the microstructure and magnetic properties of each kind of steel were studied. The results show that there exist a large number of Cu-rich metastable precipitates in the hot-rolled bands of the steels containing copper. They not only can decrease the sensitivity of the microstructures and magnetic properties of the steels to the change of process parameters but also can significantly reduce the core loss of the steels by improving the recrystallization textures without obviously decreasing the magnetic induction. Therefore, it is possible to control the microstructures and then magnetic properties of non-oriented electrical steels by the copper precipitates.