COLD DRAWING METHOD FOR FERRITIC STAINLESS STEEL PIPE

摘要

PURPOSE:To carry out the cold drawing without generating such defect as cracks, etc., by specifying the relation between the required time for drying of the film and the drying temperature when the ferritic stainless steel pipe is to be cold drawn utilizing the lubricity of the film formed by the conversion coating process. CONSTITUTION:The oxalate film forming process and the metallic soap lubricating process are applied to the ferritic stainless steel pipe which is added with such stabilizing element as titanium, niobium, etc. After that, the cold drawing is carried out at the rate of area reduction, 10-45%, utilizing lubricity of this conversion coated film; hereupon, the heating temperature T (lower than 160 deg.C) necessary for reducing hydrogen penetrated while the film forming process down to an extent allowable for the cold drawing process, and the holding time (t) seconds, are settled so as to satisfy the correlational formula, 1n t=13.4-0.05T. According to this method, the steel pipe or piping available for chemical plants, etc., can be manufactured without generating the working cracks, etc.