Ferritic nodular cast iron, casting and preparation method thereof

The invention discloses ferritic nodular cast iron, a casting and a preparation method of the ferritic nodular cast iron, the ferritic nodular cast iron comprises the following elements in percentage by mass: 92.25-94.25% of Fe, 0.09-0.38% of Cu, 2.92-3.35% of C, 2.92-3.35% of Si, 0.09-0.38% of Mn, less than or equal to 0.04% of P and less than or equal to 0.02% of S. The casting of the ferritic nodular cast iron is formed by pouring the ferritic nodular cast iron material, the core of the ferritic nodular cast iron casting is of a ferritic structure, and the core of the ferritic nodular cast iron casting is of The surface structure of the ferritic nodular cast iron is martensite. The preparation method comprises the following steps: preparing nodular cast iron, pouring a casting, cooling the casting by adopting a staged cooling chill process, and carrying out laser quenching. The ferritic nodular cast iron with the tensile strength of 450 MPa or above, the hardness of 150 HBW or above and the high elongation