| 摘要 |
PURPOSE:To produce a steel wire for non-tempered high-strength springs by subjecting a steel consisting of C, Si, Mn, Cr, Mo, V, Nb, and Fe to hot rolling then to force cooling to convert the entire part of a wire rod to martensite structure. CONSTITUTION:The steel contg. 0.15-0.35wt.% C, 1.0-3.0% Si, 0.3-3.0% Mn, and 0.7-5.0% Cr, contg. further at least one kind among 0.05-3.0% Mo, 0.01-1.0% V and 0.01-0.5% Nb and consisting of the balance Fe and inevitable impurities is hot rolled at the intermediate and finish rolling temps. preferably set at <=1,050 deg.C. Such hot rolled material is subjected to the force cooling by water cooling or blast cooling right after the rolling. The wire rod consisting of the martensite structure over the entire part is thereby obtd. The high- strength steel which has about 150kgf/mm<2> tensile strength without executing reheating such as hardening and tempering treatments, is about 150-230kgf/mm<2> in tensile strength after cold working or bluing treatment, has less fluctuating strength and has an excellent drawing value and resistance to permanent set in fatigue is thereby obtd. |
