Patent ID: 8671727
Filing Date: 2014-03-18
Classification: B21C,B24C,Y10T

Abstract:
1. A method for producing a cold drawn tube, wherein cold drawing is performed for a heat-transfer tube for a steam generator for nuclear power generation the method comprising: subjecting a starting material which is produced in a hot working method to a bright heat treatment; cold rolling the starting material to produce a workpiece which has an outer diameter and wall thickness for cold drawing to be applied thereto; subjecting an inner surface of the workpiece to a blasting treatment by use of blast grains of #100 to #350 in microgrits classification defined in ISO 8486 1996 F standard to provide a blank tube for cold drawing in which an inner surface roughness of the blank tube before drawing, when represented by an average surface roughness Ra defined in ANSI B46.1, satisfies formula (i) below; and forming an oil lubricating film on a surface of the workpiece and performing a high-pressure lubrication drawing;