High-r-value thick-specification IF automotive steel and production method thereof

The invention relates to high-r-value thick-specification IF automotive steel and a production method of the IF automotive steel. The method comprises the steps that desulfuration, bessemerizing, RH vacuum refining and continuous casting are carried out on molten iron to obtain a continuous casting sheet billet; hot rolling is carried out on the continuous casting sheet billet to obtain a hot rolling sheet billet; reeling is carried out on the hot rolling sheet billet to obtain a hot rolling steel coil; uncoiling acid pickling is carried out on the hot rolling steel coil; cold rolling is carried out on the hot rolling steel coil after acid pickling, and a cold-rolled steel sheet is obtained; the cold-rolled steel sheet is annealed in a continuous annealing furnace; the cold-rolled steel sheet after annealing is flatted; the high-r-value thick-specification IF automotive steel produced through the method has the good forming property and mechanical property and can meet the requirement of a middle-and-top-grad