Influence of chemical composition and processing conditions on the microstructure and magnetic properties of low-carbon Si-Al-Sb electrical steel sheets

•Magnetic properties of Si-Al and Si-Al-Sb electrical steels.•Si + Al and Si + Al + Sb electrical steels processed by alternative route.•In-situ phase transformation analysis by dilatometry.•Columnar grain growth in Si + Al and Si + Al + Sb electrical steels. It has been recently reported that the magnetic behavior of electrical steels containing Si + Al, can be improved by an alternative processing route, which involves the intercritical annealing of the hot-rolled bands before cold-rolling. The effects of such processing route has not been investigated in steels containing Si-Al-Sb. It has been reported that Sb can enhance the magnetic behavior of these steels. The present work reports the microstructure and magnetic properties of Si-Al-Sb electrical steels processed by the alternative processing route. Results were compared with those of Si-Al electrical steel sheets processed both by the conventional and the alternative route. Microstructural characteristics of hot-rolled electrical steel samples were modified by an intercritical annealing conducted at 850 °C from 30 min to 720 min. After this, samples were cold rolled using thickness reductions of 80 % and 90 %, and annealed at 750 °C, 850 °C and 950 °C for 8 min. Characterization of the samples included: spark optical emission spectrometry, dilatometry, optical microscopy and scanning electron microscopy, while magnetic properties were determined in a silicon steel sheet iron loss tester. Results demonstrate that, Si-Al-Sb steels processed by the alternative route exhibit better performance (higher permeability, lower coercivity, lower core loss), than Si + Al steels processed either by the conventional or the alternative route.