| 摘要 |
PROBLEM TO BE SOLVED: To provide a method for manufacturing a steel bar which prevents adhesion of smut. SOLUTION: This manufacturing method includes multistage hot-rolling for a billet (STP2) to obtain a wire rod. The wire rod is wound up in a coil form (STP3), is kept in a high-temperature environment in an anti-oxidation furnace (STP4) within 24 hours or fewer after the hot rolling, and then is air-cooled (STP5). Thereby, the wire rod is annealed to prevent its aging crack. Subsequently, the wire rod is secondly annealed (STP 6 and 7). Then, the wire rod is immersed in hydrochloric acid solution to remove the scale (STP8). Then, the wire rod is immersed in nitric acid solution to passivate the surface (STP9). Then, the wire rod is immersed in hydrochloric acid solution to remove deposits (STP10). Subsequently, the wire rod is immersed in an alkaline solution to neutralize the acid (STP11). The passivation treatment is not carried out after pretreatment (STP10). COPYRIGHT: (C)2004,JPO
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