| 摘要 |
PURPOSE:To obtain a stainless steel pipe having improved dimensional accuracy in roundness after solution heat treatment in UOE forming of a stainless steel plate by forming the stainless steel plate to a size smaller by as much as the rate of increase in diameter owing to the solution heat treatment. CONSTITUTION:In obtaining a stainless steel welded pipe by a UOE method using a stainless steel, the steel plate is formed to an outside shape smaller by as much as the rate of an increase in diameter by a solution heat treatment. Thereafter, this pipe 10 is subjected to high frequency induction heating at prescribed temp. by preheating coils 31-33 and soaking coils 34, 35, whereby the pipe is subjected to the solution heat treatment. If necessary, the pipe 10 is quickly cooled by cooling nozzles 37 from both inside and outside surfaces thereof, whereby the pipe is hardened. Restraining stands 38, 39 are provided before the heat treating part and after the cooling treatment to prevent the deterioration in the roundness of the pipe 10. The steel pipe in a small diameter state is made larger in diameter by this solution heat treatment and the stainless steel welded pipe of high dimensional accuracy is obtained. |
