Effect of Heating Rate on Microstructure Evolution and Magnetic Properties of Cold Rolled Non-Oriented Electrical Steel

The effects of heating rate(ranging from 50 to 300 ℃/s)during the final annealing process on microstructure evolution and magnetic properties of cold rolled non-oriented electrical steel were investigated.It was found that increasing heating rate increased the nucleation temperature and complete recrystallization temperature.At the same time,heating rate increasing could cause the substantially refined structures for the recrystallization grains and this grain refinement would decline when the heating rate was beyond 50 ℃/s.The recrystallization texture exhibited pronounced improvement with heating rate,such as the intensity decrease of < 111 //ND(normal direction)fiber and the intensity increase of {110}<001 Goss texture component.The texture improvement and grain size refinement caused by heating rate increasing resulted in complicated variation of the magnetic properties.The magnetic induction(B50)keeps increasing while heating rate increases from 15 to 300 ℃/s which is due to the recrystallized texture optimization caused by rapid heating.The core losses(P1.5/50)decrease while heating rate increases from 15 to 100 ℃/s;however,the core losses would increase when heating rate is higher than 100 ℃/s,which is caused by the mean grain size refinement after rapid heating annealing.The results indicate that recrystallization texture and the magnetic properties of the non-oriented electrical steel can be improved definitely by rapid heating during the final annealing treatment.