Modeling texture change during the static recrystallization of interstitial free steels
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I.
INTRODUCTION
THE characteristics of primary recrystallization textures depend on a large number of metallurgical parameters5 ~,2,3] In extra-low-carbon and interstitial free (IF) steels, it is generally observed that the intensity of the {111)//ND (normal direction) fiber increases at the expense of the {110)//RD (rolling direction) fiber. According to Hutchinson,t4] the strongest component of the recrystallization texture shifts from {111}{110) toward {111}(211) as the level of cold reduction is increased. The observations have been explained as arising from either oriented nucleation or oriented growth, as there is experimental support for the operation of both mechanisms. The oriented nucleation theories assume that the mechanism by which a strain-free nucleus is generated can only take place in grains of particular crystallographic orientations. As discussed by Hu, tS] a nucleus can be formed by the coalescence of two or more subgrains. This mechanism is more likely to occur in grains containing higher amounts of stored energy, i.e., the { 110} and { 111 } orientations in cold-rolled sheets56] According to Hutchinson,pl such orientation dependence of the nucleation process is solely responsible for the dominance of the ND fiber in the texture of recrystallized low- and extra-low-carbon steels. By contrast, strain-induced boundary migration (SIBM) is considered to be responsible for the nucleation of orientations with low levels of stored energy,[Sl as in moderately rolled bcc steels. [9] The selective growth hypothesis is based on the observation that grain boundary mobility is orientation dependent. The experimental evidence for the higher mobility of coincidence site lattice (CSL) boundaries (as opposed to random high-angle boundaries) has been reviewed by Pumphrey, t1~ According to the boundary model of Gordon and Vandermeer, tm the mobility peak differs by a few degrees from the exact CSL position. They also attributed higher L. KESTENS, CSIRA Research Associate, and J.J. JONAS, CSIRANSERC Professor, are with the Department of Metallurgical Engineering, McGill University, Montreal, PQ, Canada H3A 2A7. Manuscript submitted March 23, 1995. METALLURGICAL AND MATERIALS TRANSACTIONS A
mobilities to medium Z CSL (17 < ~ < 33) than to either lower or higher ~ CSL boundaries. By means of recrystallization experiments on Fe-3 pct Si single crystals, Ibe and Lficket~2] obtained evidence for high mobilities in the cases of 27 deg (110) (]s and 84 deg (110) (~17a) rotation relations. They reported a spread of +_ 12 deg around the exact CSL positions. According to Hrlscher et aL, t~31 the former relation is responsible for the strengthening of the { 111 }{211) component in the recrystallization texture of IF steels at the expense of the {211 }(110) rolling component. A special type of selective growth has been described by Watanabe,t~4o~5~ who showed that there is {110} plane matching (PM) between growing and matrix grains during the secondary recrystallization of 3 pct Si oriented electrical steel. Unlike a CSL b
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