Method for performing heat treatment on nodular iron casting in nodular cast iron production

Abstract

The invention discloses a method for performing heat treatment on a nodular iron casting in a nodular cast iron production. The method comprises the following steps: performing metallography detection on the nodular iron casting, judging the nodulizing grade and the matrix structure, and determining the high-temperature graphitization annealing process according to the matrix structure; loading the casting into a furnace, heating the casting to the temperature of 890-910 DEG C and keeping the temperature for 2-4h; cooling in the furnace to 740-760 DEG C and keeping the temperature for 1-3h; cooling in the furnace to the temperature of 600-630 DEG C, discharging the nodular iron casting, and performing air cooling to room temperature to finish the nodular iron casting heat treatment. By adopting the method for performing heat treatment on the nodular iron casting in the nodular cast iron production, the grain crystal is refined, the carbide generated in the freezing cold part is eliminated, the low-temperature impact of the nodular iron casting is reinforced, the hardness is reduced, the machinability is improved, various performances of the low-temperature nodular cast iron can be reached by the material, various property indices are obtained by a stable process, the volume production is realized and the cost is reduced.

Description

technical field [0001] The invention belongs to the technical field of ductile iron production, and in particular relates to a method for heat treating ductile iron castings in ductile iron production. Background technique [0002] Ductile iron with low temperature impact requires good impact performance at low temperature, and its internal quality requirements are very high. How to obtain its various performance requirements and stable production is a difficult point in material production. [0003] Impact toughness reflects the energy absorbed by the material when it breaks, and also reflects the ability of the material to resist crack initiation, development and fracture under rapid deformation conditions. Low-temperature impact toughness is a material toughness index, that is to say, ductile iron castings with high low-temperature impact toughness have high impact toughness at -50°C, and the brittle-toughness transition temperature is low, which can better overcome cold ...

AI Technical Summary

Problems solved by technology

[0005] The invention provides a method for heat treatment of ductile iron castings in the production of ductile iron, aiming to solve the problem of unsatisfa

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