| 摘要 |
Prodn. of a cold-forged steel-wire rod, having a reduced decarburised layer thickness on the surface combined with excellent cold-forging properties, is claimed. Hot steel-wire rod is rolled and then left to stand for at least 8 seconds while a layer of scale at least 8 microns thick is formed. The rod is then rapidly quenched at a rate of at least 4 deg.c/second to produce a rapidly cooled structure composed of sorbite and/or bainite, as well as a small amt. of incidental martensite. Finally, the material is subject to spheroid annealing in an inert gas having a moisture content of 0.04-0.1%. Pref. the rod contains(%) 0.2-0.6 C, up to 0.5 Si, 0.3-2.0 Mn, 0-1.5 Cr, 0-0.5 Mo, and the balance Fe.
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