Hot rolling diaphragm spring steel for automobile and production method of hot rolling diaphragm spring

The invention discloses hot rolling diaphragm spring steel for an automobile and a production method of the hot rolling diaphragm spring steel. The hot rolling diaphragm spring steel comprises the following components by weight percentage: 0.40-0.60% of C, 0.15-0.35% of Si, 0.70-1.20% of Mn, less than or equal to 0.015% of P, less than or equal to 0.008% of S, less than or equal to 0.050% of Alt, 0.10-0.30% of Mo, 0.70-1.20% of Cr, 0.10-0.50% of V and less than or equal to 0.005% N. The production method comprises the processing steps of desulfurating, smelting, refining, conducting vacuum treatment, continuously casting to form a blank, conducting segmented thermal insulation according to temperature, heating the casting blank, rolling, coiling, slowly cooling, shearing a steel band, annealing, molding, quenching, tempering and waiting for application. According to the hot rolling diaphragm spring steel and the production method, the production cost is low; a load of a rolling mill can be reduced; the comprehensive mechanical property is excellent; a steel coil is heated uniformly in the annealing process; the uniformity of a metallurgical structure is ensured; a tempered sorbite structure is obtained by heat treatment of the quenching and the tempering; the steel is separated out by compound precipitation of microalloys, such as Cr, Mo and V in the steel; and high strength and good wear-proof property of the steel are ensured.