FERRITIC HEAT RESISTING STEEL HAVING EXCELLENT CORROSION RESISTANCE AND WORKABILITY, AND ITS PRODUCTION METHOD

摘要

PROBLEM TO BE SOLVED: To provide inexpensive steel products having excellent resistance characteristics to inside corrosion (local corrosion and general corrosion) under an exhaust gas concentrating and thickening liquid environment in an exhaust system of an engine of motorcar, motorcycle etc. SOLUTION: There is found out that there is a need for strict control of the amount of solid solution P in steel in order to exhibit the excellent corrosion resistance in the environment generated by the concentrating and thickening liquid including exhaust gas components and the Ti-added highly corrosion resistant ferritic heat resisting steel is regulated in the amount of the solid solution P of the steel to≤0.15%. The method for manufacturing the same comprises performing hot rolled sheet annealing in a coil form with a box annealing furnace, holding the steel sheet for 60 seconds to 20 hours in a temperature region of 800 to 900°C and cooling the same at 5 to 40°C/hr at an average cooling rate down to 650°C. COPYRIGHT: (C)2006,JPO&NCIPI