Steel plate for high-strength high-toughness low-yield easily-welding structure and method for manufacturing same

The invention provides a steel plate for a high-strength high-toughness low-yield easily-welding structure. The steel plate comprises the following chemical components in percentage by weight: 0.02 to 0.08 percent of C, 0.30 to 0.50 percent of Si, 1.50 to 1.80 percent of Mn, 0.02 to 0.04 percent of Nb, 0.005 to 0.030 percent of Ti, 0.008 to 0.20 percent of Mo, 0.30 to 0.90 percent of Cr, 0.30 to 0.50 percent of Cu, 0.10 to 0.40 percent of Ni, 0.010 to 0.070 percent of Als, and the balance of Fe. The method for manufacturing the steel plate comprises the steps of molten iron pretreatment, rotary furnace smelting, refining, continuous casting and rolling, wherein the steel blank heating temperature before rolling is between 1,050 and 1,220 DEG C, the rolling temperature in a recrystallization area is more than or equal to 1,000DEG C, and the rolling temperature in a non-recrystallization area is between 950 and (Ar3 plus 0 to 100) DEG C; and after rolling, the temperature is held, and the plate blank is subjected to accelerated cooling. The method has the advantages of unnecessary addition of B and V, low cost, short production period, and the obtaining of the bainite plus ferrite structure without complex thermal treatment, and can control the yield of the steel plate below 0.8 under the condition of ensuring high strength, high toughness and good welding property.