Magnetic properties characterization of shear-textured 4 wt% Si electrical steel sheet
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Srinivasan Chandrasekar School of Industrial Engineering, Purdue University, West Lafayette, IN, USA; and Center for Materials Processing and Tribology, Purdue University, West Lafayette, IN 47907, USA
Kevin P. Trumblea) School of Materials Engineering, Purdue University, West Lafayette, IN, USA; and Center for Materials Processing and Tribology, Purdue University, West Lafayette, IN 47907, USA (Received 29 July 2016; accepted 17 November 2016)
Simple shear deformation via hybrid cutting-extrusion is used to produce continuous electrical steel sheet from a commercial high-silicon (nominal 4 wt%) iron alloy of poor workability in a single deformation step, a fundamentally different route from the multi-step processing of rolling and annealing currently in use. The shear texture created in the sheet is found to be quite different from that produced by rolling. The magnetic properties of the shear-textured Fe–Si sheet are measured using closed-circuit permeametry and compared with those from sheet produced by rolling of the same alloy and a commercial non-grain-oriented sheet of similar composition. Properties compared include maximum relative permeability, induction, coercivity, and hysteresis loss. The results are interpreted in terms of microstructure, texture, and composition. A unit cell representation of the shear texture components is introduced that relates the expected orientation of easy magnetization directions with the sheet axes.
I. INTRODUCTION
Rolled sheets of ferromagnetic materials serve as magnetic cores for many important electromagnetic devices, with applications ranging from large power distribution transformers to rotating electric motors.1 For improving the efficiency of these devices, the electrical and magnetic properties of the sheets composing the magnetic core must be optimized: high magnetic permeability (l 5 B/H), high saturation induction (Bs), low coercivity (Hc), and low core loss are desired. An overarching requirement of the processing is low cost. Few alloys satisfy these application requirements better than alloys of iron with silicon (Fe–Si). Commercial processing of Fe–Si sheet is done through combinations of multi-step hot and cold rolling. Two distinct types of sheets having vastly different structures and magnetic properties are produced. Sheets processed primarily by hot rolling are classified as non-grainoriented (NGO) due to a weak (near random) crystallographic texture, while the application of iterative cold rolling and high temperature annealing is used to develop Contributing Editor: Michael E. McHenry a) Address all correspondence to this author. e-mail: [email protected] DOI: 10.1557/jmr.2016.458
a strong cube-on-edge (Goss) texture resulting in grainoriented (GO) sheets. While these two products serve a significant application range, improvements in the properties of these Fe–Si sheets have been scarce in recent decades due to combined processing and alloy limitations. Such limitations have ignited new efforts to develop improved Fe–Si sheet for efficient electroma
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