Large-section cast ferrite nodular cast iron and preparation method thereof

The invention belongs to the technical field of nodular cast irons, concretely relates to control and casting production of a nodular cast iron material, and especially relates to a large-section cast ferrite nodular cast iron QT580-15A and a preparation method thereof. Performances of a separately cast test block with the wall thickness being greater than 60mm and an attached test block with the thickness of 70mm respectively meet requirements (separate cast: the tensile strength is not smaller than 580MPa, the yield strength is not smaller than 450MPa, and the elongation is not smaller than 15%; and attached cast: the tensile strength is not smaller than 530MPa, the yield strength is not smaller than 400MPa, and the elongation is not smaller than 12.5%) through selecting raw materials, controlling the components of molten iron, optimizing a nodulizer, a covering agent and a technology, determining an inoculant and the technology, and controlling the addition amount and the addition method of trace alloy elements.