| 摘要 |
PROBLEM TO BE SOLVED: To produce high-tensile steel in which the safety of structures against fracture is increased by raising energy absorption in the shifting process from the occurrence and propagation of ductile fracture to brittle fracture and which has excellent fracture resistance. SOLUTION: In this method for manufacturing the high-tensile steel having excellent fracture resistance, a steel bloom containing specific components, having <=0.4% carbon equivalent (Ceq.) and having the balance Fe with inevitable impurities is heated to a temperature between the Ac3 transformation point and 1,050 deg.C and subjected to hot rolling including hot rolling under the conditions of <=850 deg.C initiation temperature, >=750 deg.C finishing temperature and 50-95% cumulative draft. Successively, accelerated cooling at (5 to 100) deg.C/s cooling rate is started at <=750 deg.C and stopped at >=600 deg.C. By this procedure, high uniform elongation characteristics, high ductile crack propagation resistance and high toughness can simultaneously be provided.
|
