| 摘要 |
PROBLEM TO BE SOLVED: To provide a high strength hot rolled steel sheet excellent in hole-expandability, elongation and weld characteristics having strength of 700 N/mmclass or more for press worked automobile components and a manufacturing method therefor.SOLUTION: There is provided a high strength hot rolled steel sheet excellent in hole-expandability, elongation and weld characteristics containing, by mass%, C:0.03 to 0.35%, Si:0.01% to 2.0%, Mn:0.3% to 4.0%, P:0.001% to 0.10%, S:0.0005% to 0.05%, N:0.0005% to 0.010%, Al:0.01% to 2.0% and the balance Fe with inevitable impurities and having a crystal structure containing a ferrite phase of over 5%, a bainite phase of over 20% and a pearlitic phase of less than 10% by area friction and a coverage factor of the bainite phase by the ferrite phase of over 30%. |
