Nodulizing agent for high-nickel austenite ductile iron as well as preparation and application methods of nodulizing agent

Abstract

The invention relates to a nodulizing agent for high-nickel austenite ductile iron. The nodulizing agent comprises the following components by mass percent: 25-35% of nickel, 8-15% of magnesium, more than 30-40% of silicon, not more than 0.1% of rare earth, and the balance being iron and inevitable impurities, wherein the particle size of the nodulizing agent is 10-20mm. The nodulizing agent has the characteristics that the magnesium oxide content can be reduced, the yield of magnesium can be improved, the nodulizing rate and the production efficiency are improved, and the manufacturing cost is low.

Description

technical field [0001] The invention relates to a nodulizer for high-nickel austenitic nodular iron and a preparation and use method thereof, belonging to the technical field of nodulizers. Background technique [0002] High-nickel austenitic nodular cast iron is a cast iron with certain thermal strength, which has good oxidation resistance and growth resistance, and has excellent thermal shock resistance, thermal creep resistance, corrosion resistance, high temperature oxidation resistance and With low thermal expansion and low-temperature impact toughness, it is widely used in the manufacture of heat-resistant and corrosion-resistant parts and components such as seawater pumps, valves, supercharger housings, exhaust pipes, and valve seats. High-nickel austenitic ductile iron has a face-centered cubic lattice structure with closely packed atoms, and has a stable austenite structure at room temperature, and has higher thermochemical stability than ordinary ductile iron and s...

AI Technical Summary

Problems solved by technology

Because the dendrites of the high-nickel austenite material are relatively developed during the solidification process, and the rare earth with a low melting point is often adsorbed on the interface between graphite and austenite, so that the austenite circle around the graphite cannot be closed for a long time, forming a carbon atom diffusion process. Channels, which eventually lead to the appearance of fragmented graphite in the casting, and often distributed along the austenite dendrites, so ordinary rare earth magnesium nodularizers cannot be applied to the production of high-nickel austenitic materials

However, nickel-magnesium alloys have higher specific gravity and higher melting point due to their high nickel content. On the one hand, the melting temperature of the alloy will be increased, resulting in a significant increase in the content of magnesium oxide in the nodulizer. Larger, the melting point of the nodulizer increases, so when dealing with high-nickel austenitic nodular iron, the stirring force on the molten iron is weak, which easily leads to uneven distribution of magnesium in the molten iron

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