Nodulizing and inoculating treatment process for nodular cast iron

Abstract

The invention discloses a nodulizing and inoculating treatment process for nodular cast iron. The process includes the following steps that firstly, 1% of a nodulizing agent B, 0.2% of a Si-Ba nucleating agent, 0.3% of a Ba13 long-acting nucleating agent and press iron are sequentially added into a pit of a nodulizing package; and secondly, molten iron is poured into another pit from a furnace, 0.15%-0.3% of a Si-Ba nucleating agent is added during tapping, 0.1%-0.2% of a special-effect 1# metal-stream nucleating agent is added during pouring, and in order to guarantee nodulizing, molten iron obtained after nodulizing contains no more than 0.012% of S and 0.040+ / -0.004% of Mg. The special nodulizing and inoculating modes are adopted, so that the graphite precipitation peak is delayed to the later solidification period from the early solidification period of a casting, that is, most graphitizing expansion is delayed to the later solidification period when an inlet and an outlet of a cavity are solidified and closed, external liquid feeding is stopped and self-feeding can only be conducted through graphitizing expansion, and thus expansion is made to eliminate the shrinkage cavity and porosity more effectively.

Description

technical field [0001] The invention belongs to the field of metallurgy, and in particular relates to a spheroidizing inoculation treatment process of nodular cast iron. Background technique [0002] As early as the 1950s, many casting professionals proposed to solve the shrinkage cavity and shrinkage defects of ductile iron by rationally using graphite self-expansion. But so far, few people can use it flexibly. [0003] They believe that the stronger the inoculation effect, the more favorable the graphitization; the larger the graphitization expansion, the better the self-feeding effect. It is not known that the time of graphite expansion will affect the feeding effect, and some people even advocate that technological measures should be taken to advance graphitization expansion, balance expansion and contraction in the initial stage of solidification, and reduce external feeding shrinkage, thereby reducing the size of the riser the goal of. But in fact, the external feed...

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Problems solved by technology

But in fact, the external feeding conflicts with the expansion of graphite, and shrinkage defects are more likely to occur

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