Si-Al-La nucleating agent for preventing shrinkage of ductile iron casting and preparation technique thereof

Abstract

The invention discloses an Si-Al-La nucleating agent for preventing shrinkage of a ductile iron casting. The Si-Al-La nucleating agent comprises the following components in percentage by mass: 70-75%of Si, 3.2-4.5% of Al, 2.0-2.4% of La, 0.8-1.5% of Ca and the balance of Fe. By adopting the Si-Al-La nucleating agent, the problems that a riser cannot be arranged or a feeding distance is overlargeand the like for high-performance thin-walled small workpieces with complicated structures and shapes or certain parts because of geometrical position and technological limits can be effectively solved; shrinkage of the ductile iron casting can be prevented by the Si-Al-La nucleating agent; product quality is improved; the use range is wide; the limit is low; and meanwhile the cost is lowered.

Description

technical field [0001] The invention relates to a preparation process of an inoculant, in particular to a silicon-aluminum-lanthanum inoculant for preventing shrinkage and porosity of ductile iron castings and a preparation process thereof. Background technique [0002] Shrinkage porosity is a unique defect of ductile iron castings, which is more common than ordinary gray iron, also known as micro-shrinkage porosity. The macroscopic fracture morphology of shrinkage porosity is sponge-like, and small, scattered holes that are not easy to distinguish with the naked eye can be observed with the aid of a microscope. Shrinkage porosity seriously affects the performance of ductile iron castings and increases the reject rate of ductile iron castings. [0003] The shrinkage cavity and shrinkage defects of ductile iron castings have always been a headache for foundry workers. With the development of industrial technology, users have higher and higher requirements for the density and...

AI Technical Summary

Problems solved by technology

Although there are the above ways to solve the volume loss defect of ductile iron castings, in the actual production of ductile iron castings, the existing technology still cannot meet the process requirements

For example, nodular iron parts for automobiles are basically high-performance thin-walled small parts with small modulus and complex structural shapes, which have a large tendency to shrinkage and porosity; and due to large batches, they are suitable for production by high-speed wet molding lines, and the mold rigidity Low; due to geometrical position and process limitations, some parts cannot be equipped with risers or the feeding distance is too large; the method of increasing the cooling rate of the lower cooling iron is also difficult to adopt on high-speed molding lines; therefore, the problem of shrinkage porosity is often difficult to solve