Surface and Subsurface Defects Formed in a Cold-Rolled Electrical Steel

The causes for the formation of defects of different characteristics on an electrical-grade cold-rolled steel strip surface are presented. Inspection of material taken from coils that presented failure was conducted using field emission scanning electron microscopy (FEGSEM), energy-dispersive x-ray analyses (EDX), and confocal microscopy (CM). The surface and cross section analyses of selected specimens suggested that the formation of holes and scale-like defects during cold rolling could be related to a considerable number of non-metallic inclusions dispersed within the metallic matrix, the presence of both small MnS particles and silicon-rich oxides in the alloy.