The invention relates to a method for preparing a high strength thick steel plate for a large
oil storage tank in a low cost, the method particularly applies to a high strength thick steel plate for a large
oil storage tank, which is welded by line energy which is equal or less than 120 KJ / cm. The weight percentages of
chemical constituents are that carbon is 0.01-0.12 percent,
silicon is 0.15-0.35 percent,
manganese is 1.45-1.80 percent,
phosphorus is equal or less than 0.010 percent,
sulfur is equal or less than 0.003 percent, aluminum is 0.02-0.06 percent,
vanadium is 0.02-0.06 percent,
nickel is 0.20-0.40 percent,
nitrogen is 0.003-0.006 percent, and the other is
ferric, other alloying elements and inevitable impurities. The invention uses on-line
quenching and off-line
tempering processes, thereby reducing valuable alloying elements, obtaining high strength high
toughness thick steel plate which has excellent
welding performance and does not need to preheat above 0 DEG C, reducing the producing cost, saving energy, increasing production efficiency and improving
welding construction conditions, and the invention is capable of being widely used for constructions of a 10-30 cubic myriametre of large
oil storage tank.