PURPOSE: To manufacture a seamless tube consisting of high alloy steel or the like at high efficiency of rolling.
CONSTITUTION: A billet 1 consists of an allay steel contg. at least ≥5wt.% Cr or Ni, or an alloy consisting essentially of Cr, Ni or Mo is used. A steel plate 2 consists of carbon steel to which oxidation-treatment is preliminarily applied is joined to the end face on the side from where piercing of the billet 1 is started by welding. Next, the billet 1 to which the steel plate is joined is heated in a heating furnace, a hollow base stock is made by piercing the billet using a piercing plug 3 and the seamless tube is manufactured by rolling the obtained hollow base stock. In this way, the service life is improved, the life is prolonged, the frequency of plug change is decreased and the consumption unit of tool is reduced.
ARIIZUMI TAKASHI
YAMAZAKI MOTOHARU
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