T E C H N I C A L PA P E R 99%, examined by EBSD mapping. The number of crystals along the <111> direction is high in both wires11. In the wires obtained by alternate drawing, the crystals along the <100> direction are strongly oriented near the surface of the wire. These wires have a double fiber structure along the <111> and <100> directions or a fiber structure with a random crystal orientation. The above findings can explain the following results, i.e., the wires obtained by alternate drawing have slightly lower tensile strength than the wires obtained by conventional drawing, and their ductility until breakage is increased. Summary In this study, the authors examined the mechanical properties, such as the strength and ductility until breakage, the conductivity and the fracture characteristics revealed by the repeated bending test, of aluminum wires for automobile harnesses obtained by alternate wire drawing. The reasons behind the advantages of the wires obtained by alternate drawing over the wires obtained by conventional drawing were discussed on the basis of the crystal orientation mapping by XRD and EBSD. The following results were obtained. The shear strain generated on the wire surface during each pass of alternate drawing is canceled by reversing the drawing direction of the subsequent pass; thus, the equivalent strain accumulated in the wires is smaller than that in the wires obtained by conventional drawing, as revealed by FEA. The tensile strength and the breaking strain of the wires obtained by alternate drawing are 263 MPa and 0.024, respectively, indicating good mechanical properties. In particular, the tensile breaking strain is 15% higher than that of the wires obtained by conventional drawing. The number of repetitions until breakage, residual stress, and conductivity of the wires obtained by alternate drawing are superior to those of the wires obtained by conventional drawing. The reasons behind the superiority of the wires obtained by alternate drawing in terms of ductility and the number of repetitions until breakage were discussed referring to the crystal orientation mapping by XRD and EBSD. It was found that the wires have a double fiber structure along the <111> and <100> directions or a fiber structure with a random crystal orientation, leading to wires with high ductility and good fracture characteristics, as revealed by the repeated bending test. Figs. 8. Crystal orientation of drawn wire by conventional drawing (left) and alternate drawing by EBSD map10. 32%, respectively. From Fig. 6, it is confirmed that electric conductivity is decreased by the drawing process. However, comparing the alternately drawn and conventionally drawn wire, it was found that the electric conductivity of the alternately drawn wire is slightly higher than that of the conventionally drawn wire. It was considered that in the case of alternate wire drawing, suppressing the formation of additional shear strain and hence increase in the electrical resistance was inhibited. Crystal orientations analysis of drawn wires by XRD and EBSD. The authors have explained that the properties of wires obtained by alternate drawing are superior to those obtained by conventional drawing for use in wire harnesses. The reasons behind the increase in breakage elongation (ductility) and the number of repetitions until breakage are discussed in terms of the crystal orientation revealed by XRD and EBSD. Fig. 7 shows the XRD intensities at the (111), (100), (220), (311) and (222) planes, along with the {111} and {100} pole figures of wires obtained by conventional drawing (Rt = 99.8%) and alternate drawing (Rt = 99.8%). It has been reported that the XRD intensity along the <111> direction of the wires obtained by conventional drawing with a high Rt exceeding 99% becomes extremely high9. The fiber structure along the <111> direction becomes coarse and the wire strength is considered to increase. Similarly, the XRD intensity along the <111> direction of the wires obtained by alternate drawing is also high. However, the XRD intensity along the <100> direction is higher than that of the wires obtained by conventional drawing. The wires obtained by alternate drawing are considered to have a double fiber structure along the <111> and <100> directions. This finding indicates that the ductility of the wires obtained by alternate drawing increases. Fig. 8 shows the crystal orientation of the wires obtained by conventional drawing and alternate drawing with Rt = W W W. W I R E N E T. O R G Acknowledgments This study was conducted by the assistance of Japanese scientific research funds (JSPS). The authors thank the Furukawa Electric Co. in Japan for its support and providing the tested material. n J A N U A R Y 2 0 2 0 W I R E J O U R N A L I N T E R N AT I O N A L 55

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