HEAT-TREATED STEEL WIRE HAVING EXCELLENT FATIGUE-RESISTANCE CHARACTERISTICS

摘要

Provided is a heat-treated steel wire having excellent fatigue-resistance characteristics. This heat-treated steel wire has a prescribed chemical component composition and the remainder comprises iron and unavoidable impurities. A tempered martensite structure at a depth of 0.3 mm from the surface includes: no more than 0.20/µm2 Cr-based carbides having a circle-equivalent diameter of at least 0.1 µm and less than 0.3 µm; no more than 0.002/µm2 Cr-based carbides having a circle-equivalent diameter of at least 0.3 µm and less than 0.7 µm; and no more than 0.0010/µm2 Cr-based carbides having a circle-equivalent diameter of at least 0.7 µm. The residual austenite content is more than 5 vol% and no more than 15 vol%.