| 摘要 |
PROBLEM TO BE SOLVED: To remove the anisotropy of crystals generated at the time of subjecting a cold-forged product to rolling by subjecting a hot-rolled wire material to thermal annealing at a specified temp. and then executing wire drawing operation at a specified reduction of area. SOLUTION: A material subjected to hot rolling to produce a ferritic stainless steel wire or wire rod is thermally annealed at 720 to 800 deg.C and is next subjected to wire drawing operation at >=40% area reduction. In the case the thermal annealing condition is <720 deg.C, the growth of the crystal grain size is not seen, and no sufficient softening for executing wire drawing in which the area reduction is high is obtd. Moreover, in the case of the annealing temp. exceeding 800 deg.C, duplex grain size is seen in the crystal grain size. The reason why the area reduction is controlled to >=40% is that, as the area reduction at the time of the wire drawing is made larger, the crystal grains are made finer, and the anisotropy of the crystal orientation generated at the time of the hot rolling is dissolved. In the case of <40% area reduction, small shape defects are seen at the time of the cold forging.
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