New information on texture development in regular and high-permeability grain-oriented silicon steels
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I.
INTRODUCTION
THE genesis
of the sharp cube-on-edge (COE) or Goss texture in grain-oriented silicon steels has held the interest of scientists for almost half a century. The average deviation from ideal orientation in the so-called regular material (RM) is about 7 deg; this is produced in general by two stages of cold reduction with an intermediate anneal and uses MnS as grain growth inhibitor. 1 Superior-quality steels with high permeability and an average deviation of only - 3 deg (HM) have been developed 2 using only one stage of cold reduction and a combination of A1N and MnS as grain growth inhibitor. A considerable volume of research into the origin of the Goss texture has been published over the years. (References can be found in D~irmann. 3) Two specific comments can be made with respect to the early works: (a) most authors concentrated on texture studies starting with primaryrecrystallized specimens, and (b) although it was known that the texture in low-carbon steels can vary through the thickness of a strip, 4 such variation was not examined in detail. In our work, therefore, it was decided to take up a study of texture development beginning with the hot-rolled stage and to investigate the influence, if any, of throughthickness texture variation. The most important aspect of our study was, however, to apply orientation distribution function analysis (ODF) 5'6 to obtain more quantitative information. Although it has been established 7 to be a very powerful method, its application to Fe-Si has, surprisingly, so far been rather limited. 8-~3 The objective of this paper is limited to the presentation of a comparative picture of texture development in both regular and high-permeability silicon steels with selected results and highlighting of some unique features. The many complex SANAK MISHRA is Research Manager and Head, Product Development, R & D Centre for Iron and Steel (SAIL), Ranchi 834002, India. C. DARMANN, formerly with Institut fiJr Allgemeine Metallkunde und Metallphysik, RWTH Aachen, is with Hoesch Stahl, A.G., Post fach 902, 4600 Doytmund 1, Federal Republic of Germany. K. LUCKE is Director, Institut fiir Allgemeine Metallkunde und Metallphysik, Kopernikus Strasse 14, 5100 Aachen, Federal Republic of Germany. This paper is based on a presentation made at the symposium "Physical Metallurgy of Electrical Steels" held at the 1985 annual AIME meeting in New York on February 24-28, 1985, under the auspices of the TMS Ferrous Metallurgy Committee.
METALLURGICAL TRANSACTIONS A
and voluminous details of the sequence of evolution of texture in each of these steels are discussed elsewhere, RM 14 and HM. ~5
II.
EXPERIMENTAL
A. Starting Material and Further Processing In the case of RM, the starting material was a 2.3 mm thick commercially hot-rolled strip (not annealed) with the nominal chemical composition by weight percent: 3.32 Si, 0.031 C, 0.060 Mn, 0.010 P, 0.023 S, 0.0034 N, and trace AI. This was processed in the laboratory in a manner similar to that described by May and Turnbull t and Fied
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