極低温変形均一化伸線による高炭素鋼線の高強度化の検討

概要

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Recently, interest in the global environment has increased demands for strong structural components and lightweight parts. Thus, strengthening high-carbon steel wires is also needed. However, further strengthening is limited by the occurrence of delamination in twisting. The major reasons for the delamination are assumed to be (a) strain aging induced by heat generated and (b) nonuniform deformation in drawing. In this study, (1) cryogenic drawing and/or (2) uniform-deformation drawing schedules were discussed. Cryogenic drawing was realized by holding the wire in a box filled with liquid nitrogen prior to drawing. On the other hand, a uniform-deformation schedule was realized using an optimum combination of die angle and reduction in area per pass. It is found that either cryogenic drawing or uniform-deformation schedule is not effective. It is found, however, that cryogenic drawing with a uniform-deformation schedule, i.e., the combination of the two, is effective for retarding delamination and strengthening high-carbon steel wires.