TECHNICAL PAPERS Fig. 10. Measurement points of Young’s modulus. Fig. 11. Relationship between Rt and Young’s modulus (operational drawing). drawing machine, a single wire can be continuously drawn with multiple passes and simultaneously drawn at multiple positions, and drawing heat can be effectively transmitted to the next die. In the experimental drawing, however, the die was exchanged after each pass and drawing heat was not retained, which caused a difference in the effect of heat generated on the wires. Drawn wire in plant. The occurrence of dynamic recrystallization was confirmed for wires obtained by operational drawing. The metal structure in the cross section of the drawn wires by SEM was observed to determine the diameter of crystal grains. Fig. 5 shows images of the metal structures of the wires drawn with Rt = 99.47, 99.84, 99.96, and 99.99%. In Fig. 5, the structure is highly dense for the wire with Rt = 99.47%, and no dynamic recrystallization is observed. For the wire with Rt = 99.84%, however, some crystal grains are enlarged. Further increasing Rt to 99.96 and 99.99%, dynamic recrystallization progresses and the number of recrystallized grains per cross-sectional area and their diameter increases. To demonstrate the occurrence of dynamic recrystallization for the above drawn wires, the crystal orientation of the drawn wires was measured by EBSD. Fig. 6 shows maps in which the crystal orientation is visualized. Focusing on the <111> and <100> orientations only, the crystal orientations within the range of 0–10o were mapped. In Fig. 6, the blue, red and white regions represent the <111> orientation, the <100> orientation, and random orientations other than along the two orientations, respectively. As compared with Figs. 5 and 6, the orientations of the recrystallized grains shown in Figs. 5(b)-(d) are judged to be along the <100> orientation. Regarding the distribution of orientations in the entire cross section, the following distribution is observed for all samples: <100> oriented crystal grains are distributed at the center of the wire, <111> oriented crystal grains are distributed slightly outside the center, and <100> oriented crystal grains and those with random orientations are distributed further outside the center. <111> oriented crystal grains are also confirmed at the surface of the wire. Fig. 7 shows the distribution of crystal grain size for the cross-sectional area of the samples shown in Fig. 6. Also, 60 | WIRE JOURNAL INTERNATIONAL Figs. 8 and 9 show the ratios of <111> and <100> orientations to cross-sectional area and the ratios when the summation of the two orientations is assumed to be 1, respectively. In Fig. 7, crystal grains with diameters of approximately 2 μm or smaller are predominant in the cross-sectional area of all the samples. In general, the diameter of crystal grains decreases with the progress of drawing; however, for Rt of 99.84% or higher, some of the <111> oriented crystal grains change to <100> oriented crystal grains, and the diameter of the dynamically recrystallized grains gradually increases as drawing progresses. Crystal grains with diameters larger than 20 μm are observed for Rt = 99.99%. As shown in Fig. 8, the wire drawn at Rt = 99.47% has a conspicuous amount of <111> orientation. Also, the wire has a fairly amount of <100> orientation. It seems that the wire drawn at Rt = 99.47% has the structure of only <111> and <100> orientations. As for the wire drawn at Rt = 99.84%, in which dynamic recrystallization were confirmed, the ratio of two orientations to the cross-sectional area of the drawn wire decreases to extremely low level. It is thought that the conversion of the crystal orientation is caused by the occurrence of dynamic recrystallization, and that as a consequence, random orientations increase. As for the sample wires, which were drawn at bigger Rt than 99.84%, there was a <100> orientation increase in proportional with Rt. There is a remarkable progression of dynamic recrystallization with the decrease of wire diameter. This means that the wires drawn at Rt = 99.99% have more <100> orientation. Looking at the ratios of the two orientations shown in Fig. 9, the formation of <100> orientation becomes conspicuous in the wire drawn at an Rt bigger than 99.47%, where no dynamic recrystallization occurs. As a result, the phenomenon agrees with the report written by Inakazu2. The relationship between the metal structure and Young’s modulus was also examined. Fig. 6 shows that the entire structure changes nonuniformly during drawing because of the occurrence of dynamic recrystallization. Young’s modulus was measured at both near the central part and at the surface of the wire. Figs. 10 and 11 show the measurement points and results of Young’s modulus, respectively. The Young’s modulus of the drawn wires maintains a value