Pipe die powder for centrifugally casting nodular cast iron pipe and preparation process thereof

Abstract

The invention discloses pipe die powder for centrifugally casting a nodular cast iron pipe and a preparation process thereof. The pipe die powder comprises the following components in percent by mass: 60-65 percent of Si, 1.5-2.0 percent of Ca, 2.0-3.0 percent of Ba, 1.4-1.6 percent of Mn, 1.0-1.5 percent of Mg, 1.0-2.0 percent of Zr, 0.7-1.5 percent of Al and the balance of Fe; and the granularities of pipe die powder comprise less than 1.5 percent of 80 mu, 25-30 percent of 100-120 mu, 40-50 percent of 140-180 mu, 25-30 percent of 200-300 mu and less than 2.5 percent of more than 300 mu. The preparation process comprises the following steps of: preparing, melting, pouring, cooling, crushing, milling, proportioning granularities and packaging in vacuum. The pipe die powder has the advantages of uniform components, consistent melting points and reasonable granulometric class, and is beneficial to the prolonging of the service life of a pipe die of the nodular cast iron pipe, the reduction of a series of casting defects of cockles, poor nodulizing, surface cracks and the like of the nodular cast iron pipe, the improvement of the quality of the nodular cast iron pipe and the yield, and the lowering of the production cost.

Description

technical field [0001] The invention relates to the technical field of ductile iron pipe manufacture, in particular to a pipe mold powder for centrifugally casting ductile iron pipes and a preparation process thereof. Background technique [0002] Centrifugally cast ductile iron pipes have both good corrosion resistance of cast iron and good comprehensive mechanical properties of steel, and their comprehensive economic cost is lower than that of steel pipes. Therefore, the development of centrifugal ductile iron pipes is rapid, especially in water supply projects. The application of pipes has been quite extensive, basically replacing other pipes. [0003] Because the production process of water-cooled metal mold centrifugal casting ductile iron pipe is very different from the traditional casting process, its cooling speed is fast, it is easy to chill the casting, produce carbides, and affect the structure and mechanical properties of the ductile iron pipe, and the ductile ir...

AI Technical Summary

Problems solved by technology

However, in the nearly 20 years since the metal molded water-cooled centrifugal ductile iron pipe was put into production in my country, domestic pipe mold powder manufacturers have avoided the difficult smelting, fine powder recovery, high processing cost, and low product yield. The compounding process mostly adopts the cold processing process of directly mixing and compounding several raw materials after mechanical crushing to make pipe mold powder. The product composition is uneven, the melting point is inconsistent, the particle size is unreasonable, and the performance is unstable. In the production of large-diameter ductile iron pipes ( D>200mm) fashion is competent, but when used in the production of small-diameter ductile iron pipes (D<150mm), due to the substantial reduction in the amount of molten iron, the casting defects of ductile iron pipes increase, and imported pipe mold powder must be used to produce Therefore, it is very necessary to develop an efficient and excellent pipe mold powder for the production of centrifugal casting ductile iron pipes in the current market where ductile iron pipes are more and more widely used

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