A kind of production method of thick and large section ductile iron

Abstract

The invention relates to a production method of spheroidal graphite cast iron with a thick large section in the technical field of casting. The production method comprises the following steps: 1) successively and continuously adding steel scraps, scrap returns and pig iron in a smelting furnace so as to keep the existence of continuous melted iron in the smelting furnace, and finally keeping the melted iron under the overheating temperature of 1470 DEG C - 1490 DEG C for 3-5 min; 2) adding 0.2-0.4% of SiC in a casting ladle so as to pretreat the melted iron; 3) removing the melted iron in the casting ladle, wherein the height-diameter ratio of the casting ladle is required to be larger than 1.2, and removing the casting ladle to a wire feeder; 4) performing wire feeding processing on the melted iron in the casting ladle at a certain speed within the temperature range of 1400 DEG C - 1440 DEG C, and respectively, synchronously and uniformly feeding an inoculation cored wire and a spheroidized cored wire to the bottom of the liquid surface of the melted iron in the casting ladle; 5) after melted iron slags obtained after the wire feeding process in the step 4) are processed, performing casting pouring, and while performing casting pouring, uniformly adding a Si-Ba inoculant along with a melted iron flow so as to perform instant inoculation. The spheroidal graphite cast iron produced by the production method disclosed by the invention has the characteristics that the rate of spheroidization is high; the number of graphite nodules is large; the distribution is uniform; the mechanical performance is stable.

Description

technical field [0001] The invention relates to the technical field of casting, in particular to a production method of thick and large section ductile iron. Background technique [0002] Thick and large-section ductile iron castings are mainly for castings with a wall thickness ≥ 60mm. The cooling conditions of such castings are harsh, which may easily cause graphite distortion in the center of the thick wall or hot spots of the casting, the number of graphite balls will decrease, the structure will be coarse, and graphite will float. The mechanical properties decrease and more waste products appear. High waste leads to increased costs, reduced profits, reduced returns and many other problems, resulting in a vicious circle, making the quality of castings hover at a lower level. [0003] With the continuous improvement and improvement of ductile iron production technology, ductile iron castings have been more and more widely used in the manufacturing industry. The metamorp...

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Problems solved by technology

[0004] The invention aims at the problems existing in the pretreatment process of ductile iron materials in the prior art, and provides a production method of ductile iron with thick and large cross-sections, so as to improve the quality of pretreatment of molten iron of ductile iron, thereby improving the casting quality of ductile iron parts with thick and large cross-sections , reduce scrap rate

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