EFFECT OF 114 418 TEXTURE ON ABNORMAL GROWTH DURING SECONDARY RECRYSTALLI- ZATION IN GRAIN-ORIENTED STEEL
Zhiqiao LIU,Ping YANG(),Weimin MAO,Feng'e CUI
School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing 100083
Cite this article:
Zhiqiao LIU,Ping YANG,Weimin MAO,Feng'e CUI. EFFECT OF 114 418 TEXTURE ON ABNORMAL GROWTH DURING SECONDARY RECRYSTALLI- ZATION IN GRAIN-ORIENTED STEEL. Acta Metall Sin, 2015, 51(7): 769-776.
To find out the reason of poor secondary recrystallization behavior in thin-gauged grain-oriented steel, EBSD technique is applied to reveal the grain growth behavior of thin-gauged steel processed by HiB steel method under high cold-rolling reduction. Nitriding treatment with different times is conducted to ensure the occurrence of secondary recrystallization in thin-gauged grain-oriented steel and to determine the effect of nitrogen content. Attention is put on the influence of 114 418 texture on the abnormal growth of Brass and Goss grains. Results show that, at initial stage of secondary recrystallization, 114 418 grains in the surface region of sheets possess obvious growth advantage than the other oriented grains. If these grains in the surface region grew to the central layer of sheet and swallowed the nucleus of secondary recrystallization, abnormal growth could not occur. In contrast, reinforcing the inhibitors at surface region of sheet by nitriding treatment will avoid the excessive growth of surface grains and therefore improve magnetic properties of steel significantly. The {114}<418> grains are adverse to the abnormal growth of Brass-oriented and scattered Goss grains in way of island grains, but their effect on the abnormal growth of Goss grains is weaker.
Fig.1 EBSD orientation images of cold-rolled sample
(a) orientation distribution map (ND—normal direction, RD—rolling direction)
(b) {100} pole figure (TD—transverse direction)
(c) orientation distribution function (ODF), φ2=45°
Fig.2 EBSD orientation images of primary recrystallization sample
(a) orientation distribution (b) ODF, φ2=45°
Fig.3 Grain size distributions of {114}<418> and {111}<112> textures in primary recrystallization sample
Fig.4 EBSD orientation images of samples at different temperatures during secondary recrystallization annealing
(a~f) orientation distribution maps of samples at 950, 975, 1025, 1050, 1075 and 1100 ℃, respectively
(g~l) ODF, φ2=45° at 950, 975, 1025, 1050, 1075 and 1100 ℃, respectively
Fig.5 Macrostructures of secondary recrystallized grains of sample nitrided for 0 s (a), 30 s (b), 60 s (c) and 90 s (d)
Fig.6 EBSD orientation images of abnormally grown Goss grain and Brass-oriented grain of nitriding sample at 1010 ℃ during secondary recrystallization annealing
(a) abnormally grown Goss grain (yellow line indicates grain boundary misorientation <20° or >45°)
(b) {100} pole figure of Fig.6a
(c) abnormally grown Brass-oriented grain (yellow line indicates grain boundary misorientation <20° or >45°)
(d) {100} pole figure of Fig.6c
(e) {100} pole figure of all island grains in abnormally grown Goss grains
(f) {100} pole figure of all island grains in abnormally grown Brass-oriented grains
Fig.7 Difference in misorientation angle distribution between Brass-oriented grains and {114}<418> island grains in sheet interior and at sheet surface
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