Method of manufacturing steel wire for cold / warm forging and steel wire for cold / warm forging

摘要

PURPOSE:To produce the steel wire for cold and warm forging which has excellent plastic workability and the quality uniform in the entire length and circumferential direction and is entirely free from decarburization in a short period of time at a low cost by subjecting a stock wire rod consisting of a steel for machine structural use to a specific heat treatment. CONSTITUTION:While the solid or hollow coiled stock wire rod consisting of the steel for machine structural use is successively un-coiled and run, the entire section is heated from ordinary temp. up to a prescribed target temp. by a rapid heating means within 60 seconds. The wire rod is rapidly cooled by injected cooling fluid, etc., right after the above-mentioned heating up to harden the entire section. The wire rod is then heated up to the prescribed target temp. of 600 deg.C to AC1 transformation point within 60 seconds by the rapid cooling means. The entire section of this wire rod is held at the above-mentioned temp. for a prescribed period of time in a 0 to 600sec by a heat insulating device and is thereafter rapidly cooled. The steel wire for cold and warm forging having 60 to 140kgf/mm2 strength ' b and =60% threshold reduction ratio is obtd. in this way.