QT600-3 ductile iron casting and method for producing the same

Abstract

The invention discloses a QT600-3 nodular iron casting and a manufacturing method thereof. The hardness range of the nodular iron casting is between 180 and 220 HB, and the tensile strength of the nodular iron casting is more than or equal to 600 MPa. The nodular iron casting comprises 3.3 to 3.8 percent of C, 2.2 to 2.5 percent of Si, 0.2 to 0.4 percent of Mn, 0.06 to 0.08 percent of rare-earth RE, 0.03 to 0.06 percent of Mg, 0.33 to 0.4 percent of Cu, less than or equal to 0.15 percent of P, less than or equal to 0.02 percent of S, other trace impurity, and the balance being Fe. The manufacturing method thereof comprises the following steps: heating a raw material containing iron into molten iron and smelting the molten iron, and pouring the molten iron into a foundry ladle to cool; pouring the molten iron into the foundry ladle comprising nodulizing agent and copper blocks, and standing; pouring the molten iron into a mold, adding nucleating agent, and cooling the mixture; and finally obtaining the nodular iron casting through opening a box, cleaning, drawing temper, cooling, blasting ball, painting. The tensile strength of the nodular iron casting is high, and the hardness of the nodular iron casting is even.

Description

technical field [0001] The invention relates to a ductile iron casting and a manufacturing method thereof. Background technique [0002] Ductile iron is the abbreviation of ductile iron. Castings made of QT600-3 nodular iron are obtained by melting raw materials such as pig iron, scrap steel and ferromanganese through molten iron smelting, spheroidizing, pouring, and heat treatment. Among them, the main bearing cap of diesel locomotive diesel engine can be this casting . In order to achieve the performance index of the main bearing cap, flow inoculation is carried out while the above pouring is carried out, the heat treatment adopted is normalizing treatment, and tempering treatment is also carried out after normalizing treatment. The tensile strength of the main bearing cap after the above treatment is not less than 600MPa, the yield strength is not less than 370MPa, and the elongation is not less than 3%, but its hardness uniformity is poor, and the hardness range reache...

AI Technical Summary

Problems solved by technology

The tensile strength of the main bearing cap after the above treatment is not less than 600MPa, the yield strength is not less than 370MPa, and the elongation is not less than 3%, but its hardness uniformity is poor, and the hardness range reaches 180HB~270HB, which is not conducive to the mechanical properties of the main bearing cap Processing and Fitting Properties

If it is not normalized, the tensile strength of the main bearing cap will be less than 600MPa