METHOD FOR MANUFACTURING SILICON AND CHROMIUM-CONTAINING BAR-STEEL MATERIAL EXCELLENT IN SCALE DETACHABILITY

摘要

PROBLEM TO BE SOLVED: To provide a method for hot-rolling a bar-steel material with which the generation of surface flaw formed during hot-rolling the bar-steel material can be restrained without needing large investment for facility and a bar-steel material product satisfying the recent severe guarantee to the surface flaw can be manufactured.;SOLUTION: The method for manufacturing a Si and Cr-containing bar-steel material, excellent in the scale detachability, is performed as the followings: after holding a steel billet containing ≥0.05 mass% Si and ≥0.1 mass% Cr in a heating furnace at the temperature of 1000 to 1150°C within 60 min, and before extracting after heating at 1200 to 1350°C for ≥5°C/min, this steel billet is held within 10 min and extracted from the heating furnace. Thereafter, a water-vapor-oxidizing treatment for exposing the steel billet under the wet atmosphere of 30 to 60°C dew point for short time of ≤2 sec is applied for one or more times, and a high pressure water descaling and the rolling are performed.;COPYRIGHT: (C)2009,JPO&INPIT