OIL-TEMPERED WIRE AND PROCESS FOR PRODUCING THE SAME

摘要

An oil-tempered wire that has high fatigue strength and toughness after the nitriding treatment, and a method of producing the same, and a spring using the oil-tempered wire are provided. The oil-tempered wire has a tempered martensite structure. A lattice constant of a nitride layer formed on a surface of the wire is 2.870 Å to 2.890 Å when the oil-tempered wire is nitrided. The oil-tempered wire is produced by wire drawing a steel wire and quenching and tempering the wire drawn steel wire. The quenching is performed after the radiation heating is performed at 850 to 950°C for over 30 sec to 150 sec, and the tempering is performed at 400 to 600°C.