*3.3. Dimension of Drawn Tubes*

Figure 7 shows the cross sections of the drawn tubes of the selected materials at a die reduction of 0.17 (die diameter *D*die = 1.37 mm). The results observed on the copper tube were already reported in our previous paper [10]. The dotted circles in the image area are equivalent to the die diameter. For each material, all the cross sections were smaller than the die's exit hole. The cross section became smaller than the die's exit hole as the drawing speed ratio increased. Figure 8 shows the measurement results of the outer diameter of the drawn tubes on the die's exit side for each drawing condition. The error bars indicate the standard deviations. The dotted lines indicate the die diameter. The outer diameter was smaller than the die diameter for all drawing conditions. The outer diameter became smaller than the die diameter as the drawing speed increased.

**Figure 7.** Cross sections of the drawn tubes at a die reduction *R*e of 0.17 for each material. The diameter of the dotted circle was drawn to show the size of the exit hole of the die. The results of the copper tubes were already shown in our previous paper [10].

**Figure 8.** Outer diameters of the drawn tubes on the die exit side. (**a**) Die reduction *R*<sup>e</sup> = 0.05, (**b**) *R*<sup>e</sup> = 0.17, and (**c**) *R*<sup>e</sup> = 0.29. The error bars indicate the standard deviations. The dotted lines indicate the exit hole diameter of the die. The results of the copper tubes were already shown in our previous paper [10].
