| 摘要 |
<p>PURPOSE:To easily produce a high grade tie rod by subjecting a billet of low- or medium-carbon steel with specific composition to hot rolling and cold drawing under respectively specified conditions and then performing cold forging and machining. CONSTITUTION:A billet of a carbon steel which has a composition containing, by weight, 0.20-0.50% C, 0.03-0.80% Si, 0.50-2.00% Mn, <0.035% P, <0.030% S, 0.01-0.05% Al, and 0.005-0.025% N or further containing one or >=2 kinds among 0.05-0.50% Ni, 0.05-0.50% Cr, and 0.05-0.50% Mo is heated up to 1000-1150 deg.C and hot-rolled into wire rod so that rolling finishing temp. is regulated to 750-950 deg.C. The resulting wire rod is cooled at 5-50 deg.C/sec average cooling rate. Subsequently, the wire rod is cold-drawn and cold-forged so that tensile strength is regulated to >=80kgf/mm<2>, by which a material 10 having a ball joint part forming part 10a, an intermediate shaft part 10b, a hexagonal part 10c, and a screw forming part 10d is formed. Further, a small diameter part 1e is formed between a shaft part 1b and a ball joint part 1a by means of machining and screw cutting is executed on the part 10d, by which a tie rod 1 can be formed.</p> |
