Preparation method of ferritic ductile iron

Abstract

The invention relates to the field of spheroidal graphite cast iron, in particular to ferritic spheroidal graphite cast iron and a preparation method thereof. The ferritic spheroidal graphite cast iron comprises, by mass, 3.5%-3.8% of carbon, 2.4%-2.7% of silicon, 0.29%-0.35% of manganese, 0.03%-0.04% of cerium, 0.045%-0.06% of magnesium, 0.08%-0.1% of yttrium, 0.01%-0.02% of molybdenum, 0.02%-0.03% of rhenium, not more than 0.04% of phosphorus, not more than 0.018% of sulphur and the balance iron. The preparation method particularly includes the steps of (1), melting raw materials by a medium-frequency induction furnace prior to desulfurization; (2), uniformly mixing silicon carbide powder with rare earth magnesium alloy, then pouring the mixture into a spheroidizing package, covering the spheroidizing package with a first inoculant for spheroidizing and primary inoculation treatment prior to secondary inoculation treatment, and casting so as to obtain a cast; (3), subjecting the cast to heat treatment so as to obtain the ferritic spheroidal graphite cast iron. The ferritic spheroidal graphite cast iron is high in spheroidizing ratio and strength and excellent in toughness and impact plasticity, and the preparation method is simple and efficient.

Description

Technical field [0001] The invention relates to the field of nodular cast iron, in particular to a method for preparing ferrite nodular cast iron. Background technique [0002] The production of ductile iron in my country started very early. It was successfully developed and put into production in 1950. So far, the annual output of ductile iron in my country has reached 2.3 million tons, ranking third in the world after the United States and Japan. The rare earth magnesium spheroidizing agent suitable for my country's national conditions has been successfully developed, and the production technology and research work of as-cast spheroidal graphite cast iron and austenite-bainite spheroidal graphite cast iron have reached a high technical level. Ferritic nodular cast iron refers to nodular cast iron in which the ferrite content in the matrix is ​​greater than 80% and the remainder is pearlite. It has good impact plasticity and toughness, but low strength. It is used in the manufa...

AI Technical Summary

Problems solved by technology

Chinese patent CN 103060671 A discloses a "ferritic ductile iron and its preparation method". This invention adjusts the content of carbon, silicon and manganese in molten iron by selecting high-quality raw materials. The molten iron is deoxidized and purified, pretreated and spheroidized Inoculation treatment to obtain high-strength and high-toughness ferritic ductile iron, but the strength and toughness of the ferritic ductile castings can be further improved

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