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在生产大型离心复合铸铁轧辊时,对一些要求高强度的轧辊,我们以球墨铸铁作辊芯材料,其辊颈处直径为550~650mm。对于厚断面球墨铸铁件,国内多采用钇基重稀土镁合金进行球化处理。但考虑到该合金价格约为轻稀土镁合金的十倍多,所以我们最后选用轻稀土镁合金作球化剂、以75Fe－Si作孕育剂,来处理大型离心复合铸铁轧辊的辊芯。只要正确地选用原铁水成分及最终成分、适当的球化剂用量和处理温度,并进行多次孕育,用轻稀土镁合金处理厚断面球墨铸铁,同样能得到良好的机械性能。我们对几个大型轧辊的下辊颈进行心部取样,测得其铸态机械性能为σb~450MPa,δ~5%。
In the production of large-scale centrifugal composite cast iron roll, for some require high-strength roll, we use ductile iron core material, the roll neck diameter of 550 ~ 650mm. For thick cross-section ductile iron parts, the domestic use of yttrium-based rare earth magnesium alloy for ball treatment. However, taking into account the alloy is about ten times the price of light rare earth magnesium alloy, so we finally use light rare earth magnesium alloy as a nodulizer, 75Fe-Si as inoculant to deal with large centrifugal composite cast iron roll core. As long as the correct selection of the original hot metal components and the final composition of the ingredients, the appropriate nodulizer dosage and processing temperature, and repeated inoculation, with light rare earth magnesium alloy processing thick cross-section ductile iron, also get good mechanical properties. We sampled the core of the lower roll neck of several large rolls and found that the as-cast mechanical properties were σb ~ 450MPa and δ ~ 5%.