Materials Science and Engineering A 427 (2006) 301–305 Orientation dependence of stored energy of cold work in semi-processed electrical steels after temper rolling S.F. Castro a , J. Gallego b , F.J.G. Landgraf c , H.-J. Kestenbach a,∗ a Department of Materials Engineering, Universidade Federal de S˜ ao Carlos 13565-905 S ˜ ao Carlos, SP, Brazil b Department of Mechanical Engineering, UNESP, Ilha Solteira, SP, Brazil c Instituto de Pesquisas Tecnol´ ogicas, S ˜ ao Paulo, SP, Brazil Received 9 December 2005; accepted 25 April 2006 Abstract Microhardness measurements were carried out in a low carbon lamination steel after 6% of temper rolling, in order to evaluate local variations of work hardening as a function of crystallographic orientation. EBSD (electron back scattered diffraction) was used to determine grain orientations with respect to individual rolling planes and rolling directions. Hardness was shown to increase with the local Taylor factor. TEM observations and a well-known dislocation hardening model were used to confirm the equivalence between hardness values and the stored energy of cold work. A definite correlation between stored energy and Taylor factors could therefore be established, being more consistent than previous data reported in the literature. The improvement was thought to be related to the rather small plastic deformation, during which Taylor factors could be considered to remain constant. © 2006 Elsevier B.V. All rights reserved. Keywords: Electrical steels; Plastic deformation; Stored energy; Taylor factors 1. Introduction Two different but directly related research topics were inves- tigated in the present paper. From a technological point of view, the effect of grain orientation on the stored energy of cold work after temper rolling was analyzed in order to con- tribute to the understanding of texture formation during the final decarburizing and grain growth anneal applied commercially to non-oriented, semi-processed electrical steels. These steels are largely used as core material for rotating electrical machinery, representing an important commercial product for low-carbon cold-rolled sheet [1]. After annealing, the sheet may receive a so-called skin or temper-rolling pass between 5 and 10% reduc- tion in thickness, after which it is sold to the customer as a “semi-processed” product. In this case, it is the manufacturer of the electrical equipment who, after cutting and/or punching, will apply a final decarburizing anneal that is also used to adjust ∗ Corresponding author. Tel.: +55 16 3361 8501; fax: + 55 16 3351 5404. E-mail addresses: sergiocastro@cosipa.com.br (S.F. Castro), gallego@dem.feis.unesp.br (J. Gallego), landgraf@ipt.br (F.J.G. Landgraf), dhjk@power.ufscar.br (H.-J. Kestenbach). the ferrite grain size for optimized magnetic properties. In addi- tion, special steel compositions and processing conditions have been investigated in order to develop favourable textures which are well known in principle [2], but which remain difficult to be obtained in commercial practice [2,3]. From a scientific point of view, the relationship between stored energy and the Taylor factor was re-evaluated experi- mentally, using small amounts of plastic deformation in order to avoid the problem of grain rotations that are known to occur during larger deformations, and which have limited the extent of experimental confirmation of the importance of Taylor fac- tors during previous investigations. It is generally accepted that stored energy is proportional to the amount of slip activity which, in polycrystalline materials, depends on grain orientation. The stored energy of cold work is therefore supposed to change from grain to grain according to the local crystallographic orienta- tion as a function of applied stress. An important example can be found in the proper case of cold-rolled low-carbon steels for which, many years ago, the stored energy was shown to vary with the orientation of the rolling plane according to the sequence E (1 1 0) > E (1 1 1) > E (2 1 1) > E (1 0 0) [4,5]. Since stored energy represents the driving force for recrystallization, certain crystallographic orientations will be enhanced during annealing 0921-5093/$ – see front matter © 2006 Elsevier B.V. All rights reserved. doi:10.1016/j.msea.2006.04.092