Patent ID: 10920298

Abstract:
A steel plate having excellent resistance to fatigue crack growth and manufacturing method thereof, wherein the components of the steel plate in weight percentage are: 0.040-0.070% of C, 0.40-0.70% of Si, 1.30-1.60% of Mn, less than or equal to 0.013% of P, less than or equal to 0.003% of S, less than or equal to 0.30% of Cu, less than or equal to 0.30% of Ni, less than or equal to 0.10% of Mo, 0.008-0.018% of Ti, 0.015-0.030% of Nb, less than or equal to 0.0040% of N, 0.0010-0.0040% of Ca, and the balance being Fe and inevitable impurities. By controlling [% C]×[% Si] between 0.022-0.042, {([% C]+3.33[% Nb])×[% Si]}×Vcooling rate/Tcooling-stopping between 1.15×10−4˜2.2×10−3, carrying out a Ca treatment, and Ca/S=1.0-3.0 and (% Ca)×(% S) 0.28≤1.0×10−3, the optimizing the TMCP process, the finished steel plate has a microstructure which a duplex-phase structure of ferrite+uniformly and dispersedly distributed bainite and has an improved resistance to fatigue crack growth.