2004 年 44 巻 2 号 p. 404-413
The effect of chemical composition and ferritic hot rolling on the formation of texture in the hot rolled and coiled, cold rolled, and cold rolled and annealed ultra-low carbon steels was studied. One of the experimental steels was fully stabilized with respect to carbon, whereas two others were expected to have some carbon in solution under equilibrium conditions. The steels were processed to yield mainly gamma fiber texture intensities in the austenitically hot rolled condition. Three different thermomechanical treatments were applied, including rolling in the ferrite temperature region. After hot rolling and coiling, the steels were cold rolled and annealed. The crystallographic orientations for each condition were presented in the form of so-called skeleton plots along the RD-, TD- and ND-fibers. It was found that the resulting texture in the hot rolled and coiled as well as in the cold rolled and annealed steels was dependent on the degree of recrystallization of the ferritic substructure. A well-advanced state of recrystallization eliminated the detrimental rotated cube component, leaving behind texture with a complete gamma fiber. The average strain ratio, measured for the cold rolled and annealed steels, increased with advancing state of recrystallization and increasing intensity of the {111}‹110› texture component. It was also found that adding 100 ppm of Nb to the Ti alloyed ULC steel increased the average strain ratio by 15% at a given {111}‹110› texture intensity.
