| 摘要 |
High strength steel wire for spring containing, by mass %, C: 0.67% to less than 0.75%, Si: 2.0 to 2.5%, Mn: 0.5 to 1.2%, Cr: 0.8 to 1.3%, V: 0.03 to 0.20%, Mo: 0.05 to 0.25%, W: 0.05 to 0.30%, and N: 0.003 to 0.007%, having a total of contents of Mn and V of 0.70%≰Mn+V≰1.27% and a total of contents of Mo and W of 0.13%≰Mo+W≰0.35%, limiting P: 0.025% or less, S: 0.025% or less, and Al: 0.003% or less, and having a balance of iron and unavoidable impurities, having a microstructure comprised of, by volume percent, over 6% to 15% of retained austenite and tempered martensite, having a prior-austenite grain size number of 10 or more, having a density of presence of spheroidal carbides with a circle equivalent diameter of 0.2 to 0.5μm of 0.06 particles/μm2 or less, having a density of presence of spheroidal carbides with a circle equivalent diameter of over 0.5μm of 0.01 particles/μm2 or less, and having a tensile strength of 2100 to 2350 MPa.
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