| 摘要 |
PROBLEM TO BE SOLVED: To provide a method for manufacturing a seamless stainless steel tube made of two-phase stainless steel excellent in the quality of the inside surface by using Mannesmann tube making process including stretch reduction. SOLUTION: The method is provided for manufacturing the seamless steel tube having the prescribed size through stretch reduction after elongating a hollow base stock obtained by piercing a billet and, in the case of the manufacture of a tube stock for cold-rolling, the amountΔT (mm) of thickness reduction is controlled in the range specified by the following expression (a) in accordance with the working ratio Rd (%) of the outside diameter in the stretch reduction. Or, in the case of the manufacturing a finished hot-rolled steel tube, it is controlled in the range specified by the following expression (b).ΔT≥1.09×10<SP>-3</SP>Rd<SP>2</SP>-7.05×10<SP>-2</SP>×Rd+0.503 ... (a),ΔT≥1.60×10<SP>-3</SP>Rd<SP>2</SP>-5.92×10<SP>-2</SP>×Rd-0.174 ... (b). In the manufacturing method of (a), (b), it is desirable to properly design the componential composition of the two-phase stainless steel to be applied to the billet so that a manufactured steel tube is provided with excellent corrosion resistance. COPYRIGHT: (C)2005,JPO&NCIPI
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