Extra-thick tire mold steel plate with excellent corrosion resistance produced by adopting rolling instead of forging and spheroidizing annealing process and manufacturing method of extra-thick tire mold steel plate

The invention relates to an extra-thick tire mold steel plate with excellent corrosion resistance and a manufacturing method. The extra-thick tire mold steel plate is produced by adopting a process of replacing forging with rolling and a spheroidizing annealing process. The steel plate comprises the following chemical components in percentage by mass: 0.40-0.55% of C and 0.2-0.4% of Si; p < = 0.008%; s < = 0.005%; 0.60 to 0.85 percent of Mn; 0.02 to 0.04 percent of Al; nb is less than or equal to 0.01%; 0.30%-0.45% of Cr, Ni and Ti; ceq is less than or equal to 0.65; and the balance of Fe and inevitable impurities. According to the design, the ultra-thick tire mold steel plate with the thickness of 50-120 mm is produced by adopting the processes of medium C, low Mn, rapid TMCP (rolling replaces forging) and spheroidizing annealing; a specific regression equation is found through specific process parameters and corresponding corrosion resistance, and the optimal spheroidizing annealing process can be selected