Solution strengthening ferrite casting and preparation method thereof

Abstract

The invention relates to a solution strengthening ferrite casting and a preparation method thereof, and belongs to the technical field of alloys. The casting is prepared from the following components including, by mass, 3.30% to 3.75% of C, 3.5% to 3.90% of Si, 0.08% to 0.12% of Mn, 0.015% to 0.022% of P, 0.008% to 0.012% of S, 0.002% to 0.008% of Sb, 0.040% to 0.050% of Mg, 0.001% to 0.005% of Re, 0.10% to 0.50% of Cu, 0.10% to 0.50% of Ni and the balance Fe. According to the ferrite casting, by adjusting the types and the using amount of all the components of an alloy and meanwhile adding a compounded spheroidizing agent and conducting secondary inoculation treatment, the supercooling of the components of molten iron is improved, the solidification time is shortened, the stability of the ball shape of a graphite ball is ensured, and the strength and the ductility of the casting under the wall thickness of 25 mm-400 mm are ensured.

Description

technical field [0001] The invention relates to a solid solution strengthened ferrite casting and a preparation method thereof, belonging to the technical field of alloys. Background technique [0002] Wind power castings have developed very rapidly in recent years, and the export scale of castings has also continued to increase. The material grades of the four wind power ductile iron parts (hubs, bases, shafts, and bearing housings) have gradually changed from QT400-18AL or EN-GJS-400-18U-LT to High grade development, in the EN-1563-2011 edition, QT500-14 and QT600-10 only mention the performance values ​​of castings with a wall thickness ≤ 60mm. However, with the technological innovation of high performance and light weight of fans, it is an inevitable trend of technological development to replace the QT400-18AL grade commonly used in the industry with high silicon solid solution strengthening. High-silicon solid-solution ferrite ductile iron is characterized by high carb...

AI Technical Summary

Problems solved by technology

High-silicon solid-solution ferrite ductile iron is characterized by high carbon and low-silicon, and the tendency of the material to shrink and porosity is greater than that of conventional QT400-18AL. High-silicon promotes the formation of ferrite and high content of ferrite, but high-silicon also The solubility of carbon in austenite is reduced, resulting in a decrease in the ability to dissolve carbon in molten iron. When the carbon content is too high, the combination of free carbon with iron atoms or elements that are easy to form carbides leads to a decrease in the degree of graphitization. It will lead to the formation of a large amount of primary graphite, and the accumulation of primary graphite on the upper surface of the casting will lead to the deterioration of mechanical properties. When the carbon is low, under the condition of high silicon, the carbon-poor area is insufficient due to insufficient graphite expansion volume, and the solidification volume shrinks too much, resulting in shrinkage defects.

If the silicon content is too high, the fluidity of the molten iron will become poor, which is not conducive to the removal of secondary slag. The temperature of the primary crystal of the high-silicon molten iron is high, the time from the primary crystal to the completion of crystallization is prolonged, the liquid growth time of graphite balls is long, and graphite is deformed due to the influence of trace element segregation. growth, leading to the formation of nail-like and water grass-like graphite, so the mechanical consistency of high-silicon ductile iron is still difficult to control

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