| 摘要 |
PURPOSE:To produce an extremely fine wire having ultra-high strength by subjecting the steel wire contg. specific ratios of C, Si and Mn to heating, cooling and cold drawing under specific conditions and specifying the structure and the total content of H. CONSTITUTION:A steel wire contg., by weight %, 0.01-0.50% C, <=3.0% Si and <=5.0% Mn and consisting of the balance iron and unavoidable impurities is heated to Ac1-1,100 deg.C temp. at <=4.5mm wire diameter and is then cooled. The composite structure in which the low-temp. transformed and formed phase consisting of the martensite and bainite permitted to partly contain residual austenite or the mixed structure composed thereof, i.e., the mixed structure composed mainly of a massive phase and acicular phase is dispersed in a 10-75% volumetric fraction range in the ferrite phase is obtd. by this treatment. The wire is then cold rolled to <=0.5mm wire diameter and the total content of H in the steel is reduced to <=1ppm. The ultra-high strength extremely fine wire having >=300kgfmm<2> strength and <=0.5mm wire diameter is thereby obtd.
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