Production method of nodular iron casting and nodular iron casting prepared by adopting method

Abstract

The invention discloses a production method of a nodular iron casting and the nodular iron casting prepared by the method. The production method comprises the following steps: proportioning; the waste steel, the spheroidal graphite pig iron, the carburant and the spheroidizing agent are mixed according to a certain proportion; a smelting procedure; the mixed ingredients are added into a smelting furnace to be smelted, and molten iron is obtained; tapping and inoculating molten iron; adding a first inoculant for inoculation when the molten iron is discharged from the furnace; a spheroidizing inoculation procedure; a second inoculant is added in the spheroidizing process for inoculation; and in the casting process, a third nucleating agent is added for casting stream inoculation. And the effective time of all-time pouring inoculation is prolonged. The number of distorted graphite nodules in a metallographic structure is reduced, the inoculation effect of molten iron of a ladle tail casting at the last stage of pouring is fully guaranteed, the mechanical performance and the metallographic structure consistency of the whole ladle of poured casting are improved, and the qualified rate of the mechanical performance and the metallographic structure of a nodular iron casting made of a high-toughness material and a ladle tail inspection test block reaches 95% or above.

Description

technical field [0001] The invention relates to the technical field of ductile iron castings, in particular to a production method of ductile iron castings and ductile iron castings produced by the method. Background technique [0002] The inoculation process of spheroidal graphite castings in the current foundry production usually adopts the double inoculation process of simultaneous inoculation with silk feeding and inoculation with flow during pouring. The double inoculation treatment process is a relatively mature inoculation treatment process in the field of ductile iron production at present, so that the reasonable control of the production process parameters can meet the requirements of the metallographic structure of the product material. [0003] However, when producing as-cast high-performance, high-toughness QT400-15 / 18, QT500-7 or QT600-7 grades of ductile iron castings, the content of metal and non-metallic elements that affect spheroidization in cast pig iron, ...

AI Technical Summary

Problems solved by technology

[0003] However, when producing as-cast high-performance, high-toughness QT400-15 / 18, QT500-7 or QT600-7 and other grades of ductile iron castings, the content of metal and non-metallic elements that affect spheroidization in cast pig iron, especially metal titanium The content of (Ti) has not been effectively controlled, the content is too high, and the pouring time is too long

Take the inspection test block at the end of the package, the elongation (A%) of the toughness index of the casting will be significantly reduced, and in severe cases, the elongation of the casting will be unqualified

In addition, because the effective pouring time of inoculation has not been extended, the inoculation of castings declines in the later stage of pouring, and the number of graphite balls is more distorted.

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