| 摘要 |
PROBLEM TO BE SOLVED: To provide a method of surely manufacturable a high carbon steel sheet capable of meeting the recent demand of users for simplification of a working process and lowering in temperature and shortening in time of heat treatment, having high ductility and high hardenability, and having a composition specified by a carbon steel for machine structural use, a carbon tool steel stock, or a cold-rolled steel strip for spring. SOLUTION: At the time of manufacturing a high carbon steel sheet having a component system specified by a carbon steel for machine structural use or a carbon tool steel stock or a cold rolled steel strip for spring, a steel plate where hot rolling is finished by performing heating treatment at a temperature of >=Ar3 after hot roughing and spheroidal comentite rate is regulated to >=80% is cold rolled at a draft of >=30% and then annealed in the temperature range between 600 deg.C and the Ac1 transformation point to form cementite grains of <=1.5 aspect ratio and ferrite grains of <=1.3 aspect ratio.
|
