Preparation method of large-tonnage nodular cast iron casting

Abstract

According to the preparation method of the large-tonnage nodular iron casting, the number of balls is large, spheroidization is uniform, spheroidal graphite distortion is small, and the deformation amount of the casting in a casting state is small. The preparation method creatively adopts a ladle-to-ladle spheroidization to adjust the temperature so that the temperature can be controlled, and a four-time composite inoculation block technology is adopted; the number of large-tonnage ductile iron graphite nodules in a cast state is remarkably increased, and finally it can be guaranteed that the number of cast nodules is large, spheroidizing is uniform, deformity is avoided, and the mechanical property is guaranteed; meanwhile, the compacted blocky inoculant is adopted to inoculate the molten iron before and after spheroidizing, slow-release inoculation is achieved through multiple times of slow release, the molten iron fully exists in a temperature and concentration fluctuation area, and therefore the graphite nodules are numerous, round and uniform; according to the method, the spheroidal graphite can be stably obtained, the distortion is small, and the high elastic modulus can be obtained, so that the deformation of a casting in an as-cast state is reduced.

Description

technical field [0001] The invention relates to a casting method for iron castings, in particular to a preparation method for large-tonnage ductile iron castings. Background technique [0002] The matrix structure of QT600-3 is pearlite-based ductile iron. It has the characteristics of high strength, high stiffness, medium toughness and plasticity, good wear resistance and good casting performance. It has high comprehensive performance and is widely used in various dynamic machinery. Crankshaft, connecting rod, hydraulic cylinder block, clutch plate and other parts and machine tool castings. At present, in the casting production process, the wall thickness of large beams varies from 20 to 200 mm. The gray iron manufacturing process is simple and feasible, but its mechanical properties are poor, the elastic modulus is low, and the as-cast deformation is large. Using ductile iron to make beams, its mechanical properties will double, and its elastic modulus will double, which ...

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Problems solved by technology

[0003] At present, nodular iron is used to manufacture large-tonnage beams. It is necessary to overcome and solve the small number of graphite, the unbalanced amount of graphite, the excessive amount of carburized body at the thin wall, and the insufficient pearlite content at the thick wall. Preventing graphite distortion and other problems at the thick and large section of the guide rail

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