MANUFACTURE OF STAINLESS STEEL PIPE HAVING LAYER WITH FINE-GRAINED STRUCTURE

摘要

PURPOSE:To manufacture simply and easily a stainless steel pipe having a layer with a fine-grained structure on the inside by wetting the inside of an austenitic stainless steel pipe with an aqueous ammonium salt soln. having a specified concn. or above, and subjecting the whole pipe to soln. heat treatment at a specified temp. or above. CONSTITUTION:The inside of an austenitic stainless steel pipe is wetted with an aqueous soln. contg. an ammonium salt, especially ammonium carbonate by >=5g (expressed in terms of anhydride) per 100g soln., and both ends of the pipe are sealed with heat insulators. The whole pipe is then subjected to soln. heat treatment at >=1,000 deg.C to manufacture a stainless steel pipe having a layer with a fine-graind structure on the inside.