Titanium microalloying hot-rolling thick steel plate with low yield ratio and high strength and production process of steel plate

The invention discloses a titanium microalloying hot-rolling thick steel plate with low yield ratio and high strength and a production process of steel plate. The titanium microalloying hot-rolling thick steel plate comprises the chemical components in percentage by weight: 0.15-0.18 percent of C, 0.20-0.40 of Si, 0.50-0.80 percent of Mn, less than or equal to 0.020 percent of P, less than or equal to 0.010 percent of S, 0.060-0.080 percent of Ti, 0.010-0.030 percent of Als, less than or equal to 0.35 of carbon equivalent value (CEV percentage). The production process comprises the following steps of: 1) melting and carrying out continuous casting: melting molten steel and casting the molten steel into blanks according to set components; 2) rolling: in the rolling process, heating temperature of casting blanks is controlled between 1,220-1,270 DEG C, the temperature preservation time is more than or equal to 180 minutes, the rolling temperature in a recrystalline region is more than or equal to 105 DEG C and a finish rolling temperature in a non-recrystalline region is less than or equal to 860 DEG C; 3) cooling after rolling: in the cooling process, the cooling speed of a steel plate subjected to the finish rolling is15-40 DEG C/s; and 4) straightening the steel plate and then stacking to slow cooling. The low-yield-ratio high-strength hot-rolling steel plate of which the thickness is 40-80mm, the tensile strength is more than or equal to 550MPa, the elongation rate is more than or equal to 25 percent, the yield rate is less than or equal to 0.80, and the welding performance and the forming performance are high can be produced; and moreover, expensive alloying elements Cr, Ni, Mo, Cu and the like are not added into the produced hot-rolling steel plate with high strength, so that the production cost is low.