| 摘要 |
PROBLEM TO BE SOLVED: To provide a method for producing rod steel by which pock mark is restrained and the improvements of quality and productivity of the rod steel are improved. SOLUTION: Multi-stage hot-rolling is applied to a billet (STP2) to obtain a wire rod. The wire rod is wound as coil-state (STP3) and held under high temperature atmosphere with a non-oxidizing furnace within 24 hr from the hot-rolling (STP4), and successively, air-cooled (STP5). In this way, the wire rod is annealed to prevent aging crack of the wire rod. Then, the wire rod is applied to the second annealing (STP6, 7) and successively, applied to the first pickling. This pickling includes steps of dipping the wire rod into hydrochloric acid water solution bath (STP8), high temperature salt bath (STP9), hydrochloric acid water solution bath (STP10), and nitric acid water solution bath (STP11), and washing the rod by water (STP12), in this order. Successively, the wire rod is applied to pickling (STP13-17). The wire rod having no scale and no pock mark is shipped through these processes. COPYRIGHT: (C)2004,JPO
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