Low-Ni and low-Cr corrosion-resistant nodular cast iron and preparation method thereof

Abstract

The invention relates to low-Ni and low-Cr corrosion-resistant nodular cast iron and a preparation method thereof, and belongs to the technical field of casting alloys. The alloy comprises the following chemical components: 3.3-3.8% of C; 2.4% to 2.8% of Si; mn: < = 0.4%; less than or equal to 0.05% of P; s: less than or equal to 0.025; 2 to 3 percent of Ni; cr: 0.2 to 0.4%; 0.03 to 0.06 percent of Mg residue; re residue: 0.02-0.05%, and the balance being Fe. The preparation method comprises the following steps: (1) adding waste steel, pig iron, nickel plates, ferronickel, foundry returns and the like into an intermediate frequency furnace to be smelted into molten iron; (2) spheroidizing and inoculating the molten iron; and (3) pouring is conducted, stream inoculation is added during pouring, and the high-performance corrosion-resistant nodular iron casting is obtained. The spheroidization level of the prepared spheroidal graphite cast iron is 1-2 levels, the spheroidization rate is larger than or equal to 90%, the matrix structure is ferrite and pearlite, the tensile strength is 500-550 Mpa, the ductility is larger than or equal to 10%, and the spheroidal graphite cast iron can normally work in the marine environment. And part of duplex stainless steel products can be replaced, and the effect is remarkable.

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