| 摘要 |
PROBLEM TO BE SOLVED: To provide a high-strength steel plate with superior arrestability which has high strength and is free from deterioration in HAZ toughness and from anisotropy at a low cost. SOLUTION: The high-strength steel plate has a chemical composition containing, by mass, 0.03 to 0.15% C, 0.1 to 0.5% Si, 0.5 to 2.0% Mn, up to 0.02% P, up to 0.01% S, 0.001 to 0.1% Al, 0.005 to 0.02% Ti, 0.15 to 2% Ni, 0.001 to 0.008% N, with the balance being iron and unavoidable impurities, and microstructure of ferrite and/or pearlite with bainite as the mother phase wherein the average Heywood diameter of grains having crystal orientation differences of 15°or above is 15μm or below in the regions spread up to the depth of 10% of the plate thickness from the face and the back and that is 40μm or below in the other region. COPYRIGHT: (C)2008,JPO&INPIT |
