High strength steel for structure having excellent fatigue crack arrestability and manufacturing method thereof

摘要

The structural high strength steel having excellent fatigue crack propagation suppression characteristics according to one embodiment of the present invention is characterized by containing 0.02 to 0.12% of C, 1.7 to 2.5% of Mn, 0.01 to 0.8% of Si, 0.005 to 0.10 of Nb, 0.005 to 0.1% of Ti, 0.005 to 0.5% of Al, not more than 0.02% of P, not more than 0.004% of B, not more than 0.015% of N, not more than 0.01% of S and remaining Fe and unavoidable impurities, And the surface layer portion includes tempered bainite as a base structure, fresh martensite as a second phase, and austenite as a residual structure, , And the center portion may include lasbenite.