Effect of pre-annealing prior to cold rolling on the precipitation, microstructure and magnetic properties of strip-cast non-oriented electrical steels

• 来源期刊: 材料科学技术（英文版）
• 年，卷（期）: 2017,（12）
• 页码范围: 1465-1474
• 页数: 10页
• 语种: 英文

摘要

A novel processing route involving strip casting,pre-annealing treatment,cold rolling and recrystallization annealing was applied to a Fe-2.6％Si steel to improve the magnetic properties.The impact of as-cast strip pre-annealing on the microstructure,texture,precipitation and magnetic properties were investigated by electron probe micro-analysis,transmission electron microscopy,and X-ray diffraction analysis,etc.It was found that the precipitation of second-phase particles during strip casting was restrained by rapid solidification.The absence of pre-annealing led to the occurrence of a large amount of 20-50 nm MnS precipitates in the final annealed sheets,which is responsible for fine grains and high core loss (4.01 W/kg) due to grain boundary pinning effect.Although the microstructure and texture of900-1000 ℃ pre-annealed samples were similar to those of as-cast strip,significant grain coarsening together with the strengthening of λ-fiber texture was observed in the 1100 ℃ pre-annealed strips.In comparison with the case of as-cast strip,a higher amount of large-sized precipitates consisting of manganese sulfide and/or aluminum nitride occurred in matrix after pre-annealing.Correspondingly,in the final annealed sheets,the number density of precipitates with sizes smaller than 100 nm was substantially reduced,and 100-200 nm and 200-500 nm sized particles became more dominant in samples subjected to 30-min and 120-min pre-annealing treatments respectively.In addition,the average grain size of final annealed sheets increased with the pre-annealing temperature and time because of the weakened pining effect of coarsen precipitates.Ultimately,the magnetic induction of samples subjected to pre-annealing was slightly increased and ranged from 1.73T to 1.75T owing to the enhancement of {100} recrystallization texture,and simultaneously the core loss significantly decreased until a minimum of 3.26 W/kg was reached.Nevertheless,large number of 200-500 nm particles presented during pre-annealing for 120 min could weaken the improvement in core loss which is likely associated with the pinning effect on magnetic domain wall.