| 摘要 |
PROBLEM TO BE SOLVED: To provide a method for heating a billet, applying the optimum heat pattern to the pipe-making of a high Cr-based seamless steel pipe having a little defect in the internal surface. SOLUTION: In a pre-heating process for billet with a heating furnace before piercing-rolling the high Cr-based seamless steel pipe, the inner part of the heating furnace is divided into a preheating zone, a heating zone and a soaking zone and in the case of using Ta(°C) for targeted extracting temperature at the outlet side of the soaking zone, the heat pattern in the heating furnace is made to≤Ta(°C) in the pre-heating zone, to Ta(°C)±10°C in the heating zone and to Ta(°C) in the soaking zone. COPYRIGHT: (C)2007,JPO&INPIT
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