Low-cost production process for as-cast high-elongation nodular cast iron

Abstract

The invention discloses a low-cost production process for as-cast high-elongation nodular cast iron. The method comprises the following steps of: selecting materials; burdening, namely preparing 20 to 45 weight percent of Z18 or Z22 new cast iron, less than 55 weight percent of foundry returns and 30 to 55 weight percent of scrape steel; smelting, namely feeding the prepared materials into a furnace and smelting; nodulizing, namely nodulizing by a nodularizing process; and performing instantaneous inoculation by using an inoculant during casting and purifying simultaneously to obtain the as-cast high-elongation nodular cast iron. The nodular cast iron which is obtained by the low-coast production process for the as-cast high-elongation nodular cast iron is the as-cast high-elongation nodular cast iron, middle and high-temperature ferritizing annealing is not needed, and the elongation can reach over 10 percent; and a large amount of scrape steel materials and foundry returns are used, so that cost is reduced, and the production cycle of a cast is shortened; the selection range of the ductile iron raw materials is widened; the sinkhole of the cast is avoided; cost is saved; and few ferro-silicon alloy or no ferro-silicon alloy is added into a furnace rear.

Description

technical field [0001] The invention relates to the technical field of casting, in particular to a production process of low-cost as-cast high-elongation nodular cast iron. Background technique [0002] In the field of casting, ductile iron with an elongation greater than 10% is called high-elongation ductile iron, which is widely used in the machinery industry and automobile manufacturing industry. [0003] The general production process of high elongation ductile cast iron is to use the chemical composition of carbon (C) 3.5-4%, silicon (Si) 2.0-2.5%, manganese (Mn) 0.2-0.6%, phosphorus (P) ≤ 0.06%, Sulfur (S) ≤ 0.03% as-cast nodular cast iron, through medium and high temperature annealing above 800-950 ℃ to meet the elongation requirement of more than 10%. [0004] The following three deficiencies in the production process of the above-mentioned high-elongation ductile iron are more and more recognized and valued by the industry. First, because high-temperature anneali...

AI Technical Summary

Problems solved by technology

This is a relatively low-carbon and high-silicon high-toughness ductile iron production process. Because it needs to be annealed at 820±20°C, it not only wastes energy, but also increases production costs, and also prolongs the production cycle; Carbon is relatively low, at 3.0-3.2%, the graphitization ability of ductile iron is insufficient, castings are prone to shrinkage defects, and in order to prevent castings from shrinkage, it is necessary to increase the riser or cold iron; because the molten iron is relatively carbon Low, at 3.0-3.2%, so the ability of graphite to form nuclei decreases, resulting in a decrease in casting nodularity and graphite morphology

[0006] The current production of ductile iron is mainly obtained by using new iron (Q10-Q16) and returning materials to melt and then spheroidizing, or adding a small amount of scrap steel to the traditional nodular cast iron ingredients, and the addition amount is no more than 15%. Need to add a lot of new iron, the casting material is mainly new iron, high cost and low profit

Images