Production process of high-elongation nodular cast iron being as cast condition

Abstract

The invention discloses a production process of high-elongation nodular cast iron being as cast condition. The production process comprises the following steps: sorting; burdening: taking materials by weight percentage as follows: 35-45% of cast iron Z18 or Z22, less than 35% of foundry returns and 30-55% of steel scraps; melting: putting burdened materials into a furnace for melting, melting the materials into molten iron, rising the temperature of the molten iron to be 1600-1650 DEG C, carburetting and complementing silicon; then conducting desulfuration process; complementing oxygen and reducing manganese and conducting dephosphorization process; finally carrying out on-the-spot chemical contents analysis, adjusting the chemical contents, conducting the next operation after the chemical contents are qualified; balling by utilizing pour-over method; and breeding instantly by adopting an inoculant when in casting so as to obtain the high-elongation nodular cast iron being as cast condition. According to the high-elongation nodular cast iron being as cast condition provided by the invention, the cost is lowered, the production period of a cast is shortened; the sorting range of the raw materials of the nodular cast iron is enlarged; the cast can not shrink easily; and the cost is saved, silicon iron alloy does not need to be added or is little added after the casting treatment.

Description

technical field [0001] The invention relates to the technical field of casting, in particular to a production process of as-cast high-elongation ductile iron castings. 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 method 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 method of high-elongation ductile iron are increasingly recognized and valued by the industry. First, high-temperature annealing will cause energy consumption and...

AI Technical Summary

Problems solved by technology

This is a relatively low-carbon and high-silicon high-toughness ductile iron production method. 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

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