Texture and Microtexture Evolution in an Ultra‐Low Carbon Steel During Recrystallization

Abstract

Recrystallization texture and microtexture in a cold-rolled ultra-low carbon steel were investigated using X-ray diffraction and electron backscattered diffraction based orientation imaging microscopy (EBSD/OIM). Aspects such as nucleation, evolution of the volume fraction, and grain size were considered. Special emphasis was put on the grain coarsening of various texture components during recrystallization: an important grain selection associated with a significant advantage in size and number of the {111} recrystallized grains is observed. This grain selection gives rise to the development, in the last stages of recrystallization, of a strong c fiber associated with good drawing properties.Recrystallization and texture evolution during continuous annealing of cold-rolled low-carbon steel have been studied by many authors. [1±3] A strong c-fiber texture appears to be responsible for the high formability in low-carbon steels. Two main theories based on oriented nucleation [4,5] and selective growth [6,7] have competed for an interpretation of texture development and some attempts have also been made to find complementary approaches based on advantage in frequency or size. [8,9] EBSD techniques have been used to analyze the evolution of the grain size and volume fraction of certain texture components during the recrystallization process.The material used was an ultra-low carbon steel whose composition is shown in Table 1. This steel was industrially produced and processed by casting to about 85 % cold reduction.After cold rolling, the material was laboratory annealed to obtain different amounts of recrystallization ( Table 2). The annealing cycles were performed on a laboratory CA simulator. The samples were heated in a protective atmosphere up to the soaking temperature, in the 580±700 C range, at a rate of about 17 C/s. Soaking time was 60 s, followed by gas cooling to the over-aging temperature (400 C) at a rate close to 40 C/s. The samples were then over-aged for 100 s and finally cooled to room temperature.Texture measurements were carried out using a Philips X'pert-MRD X-ray diffractometer with Co Ka radiation and the resulting data were analyzed with the MTM-HFM program to determine the orientation distribution function (ODF).Orientation imaging microscopy was carried out in a Philips XL30cp scanning electron microscope (SEM), using TSL (TexSEM Laboratories) MSC 2200 equipment.Quantitative metallography was carried out on the EBSD orientation images for different texture components. The components considered are the c-fiber grains having a {111} plane perpendicular to the normal direction (ND), the cube grains having a {100} plane perpendicular to ND, and finally the grains with a {110} plane perpendicular to ND. The orientation tolerance, for the definition of the texture components, is 15 in all cases. The rest of the grains that cannot be identified within these categories are hereafter called ¹othersª.Partially and fully recrystallized samples were analyzed and the criterion for grain definition in a p...

Generalized pole figures from post-processing whole Debye–Scherrer patterns for microstructural analysis on deformed materials

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Determination of hot and cold rolling textures of steels: Combined Bayesian neural network model

“…The retardation of austenite recrystallisation in Nb steel during hot rolling is attributable to two complementary factors: the presence of solute Nb in the austenite and the precipitation of Nb carbonitrides in the matrix. Finally, as it is well known, 25 25,26 the unrecrystallised austenite leads to a finer microstructure after austenite to ferrite transformation, and the finer the microstructure, the lower the I (111)/ I (100) ratio,27 which can explain the decrease in r m value in Nb bearing steels as compared with Ti steels after the hot rolled stage.…”

Cold Rolled Microstructure and Its Evolution during Recovery and First Recrystallisation Stages in Low Carbon Steels

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