As-cast high-strength high-elongation synthetic nodular cast iron and preparation method thereof

Abstract

The invention relates to the field of as-cast high-strength high-elongation synthetic nodular cast iron. The invention relates to as-cast high-strength high-elongation synthetic nodular cast iron anda preparation method thereof. The nodular cast iron is characterized in that under the as-cast condition, the nodular cast iron meets performance requirements that the tensile strength Rm is larger than or equal to 700 MPa, and the percentage elongation A after fracture is larger than or equal to 10%; the matrix is a pearlite-ferrite mixed matrix; the content of pearlite is 55%-75%, a spheroidizing grade is 1-2, a graphite size grade is 6-7, the nodular cast iron is composed of elements, by mass, 3.5%-3.7% of C, 2.9-3.3% of Si, less than or equal to 0.2% of Mn, less than or equal to 0.035% ofP, less than or equal to 0.02% of S, 0.5%-0.7% of Cu, 0.55%-0.75% of Ni, 0.030%-0.065% of Mg and the balance of Fe and trace elements. The method has the beneficial effects that scrap steel and raw material pure iron are adopted for recarburization, base iron is smelted in a medium-frequency induction furnace, then pretreatment, spheroidizing treatment and inoculation treatment are conducted, final pouring is conducted, and QT700-10 is achieved under the as-cast condition.

Description

technical field [0001] The invention relates to the field of synthetic nodular cast iron with high strength and high elongation in as-cast state. The invention is a synthetic nodular cast iron with high strength and high elongation in as-cast state and a preparation method thereof. It belongs to the field of high-performance metal materials and is mainly used for automobiles, high-speed rail parts and mechanical parts requiring high comprehensive mechanical properties. Background technique [0002] Ductile iron has low cost and excellent comprehensive performance. It is widely used in engineering fields and maintains continuous and stable development and growth. Replacing stamped and welded parts and steel castings with ductile iron parts can bring many advantages such as cost reduction, structural stability, and rigidity improvement, but it also puts forward higher requirements for the comprehensive mechanical properties of ductile iron. Among the grades of ductile iron s...

AI Technical Summary

Problems solved by technology

The tensile strength of ductile iron produced by this method reaches 700MPa, but the elongation is only about 4.5%. Although it meets the requirements of the current national standard QT700-2, it cannot meet the higher elongation requirements of materials of the same grade.