Long-acting synthesizing process of heavy sectioned ductile iron

Abstract

The invention relates to a long-acting comprehensive treatment process of heavy wall ductile iron. The process comprises: placing ductile iron special pig iron materials and scrap steel in an appropriate amount in a medium frequency induction furnace, and smelting the materials at a temperature between 1350 and 1450DEG C according to the conventional method of: adding 0.1 to 2.0 percent of Cu; then adding 1 to 5 percent of nodulizer into a nodulizing ladle for nodulizing graphite, wherein the compositions of the nodulizer include: 10.0 to 12.0 percent of Mg, 2.0 to 3.0 percent of rare earth, 40.0 to 45.0 percent of Si, 2.5 to 3.0 percent of Ca, 2.5 to 2.9 percent of Ba, less than 1.5 percent of Al, balance Fe; and putting 0.1 to 1 percent of inoculant in a casting ladle in advance and pouring liquid iron into the casting ladle, the compositions of the inoculant have: 70.0 to 75.0 percent of Si, 0.5 to 0.6 percent of Ca, less than 1.5 percent of Al, 1.0 to 1.2 percent of Bi, balance Fe,and finally casting products. The process has the advantages of: improving the form of graphite, reducing degenerating graphite, and obviously improving the nodularity of heavy wall nodular iron andcomprehensive mechanical properties of castings.

Description

technical field [0001] The invention relates to a long-term comprehensive treatment process of thick-walled nodular cast iron, which belongs to the technical field of cast iron materials. Background technique [0002] Compared with general medium and thin-walled castings, thick-walled ductile iron has many different and more complicated problems. Due to the slow cooling rate of thick-walled cast iron, the eutectic time in the solidification process is long, and problems such as graphite distortion, ball number reduction, coarse structure, composition segregation and graphite floating appear. Among them, the problem of abnormal graphite has attracted many scholars to conduct a lot of research. Since the crystallization of metals always occurs in the supercooled liquid phase, supercooling is the decisive factor affecting the driving force of phase transformation, thereby affecting the crystal growth morphology. The degree of undercooling (ΔT) of graphite into spheres is gene...

AI Technical Summary

Problems solved by technology

However, under normal casting conditions, it is very difficult to meet the undercooling required for spheroidization only from the cooling rate. Therefore, it is necessary to find a way to increase the undercooling from the composition of the alloy.

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