摘要我国是一个铸铁生产大国，步入 21 世纪以来，球墨铸铁生产更是迎来一个 高速增长的阶段。兼具优良性能以及低廉的制造成本，球墨铸铁大量应用于工业 各个领域，其中最有发展前途的是高强、高韧性球墨铸铁，它赋予了材料更高的 机械性能和工艺性能。本文介绍了高韧球铁优异性能、研究现状和前景，并着重 介绍了 Si 在球墨铸铁中的作用和 Si 固溶强化球墨铸铁的优越性，探讨了高 Si 球墨铸铁工艺的可行性。81343

本文选择 QT500-14 为实验方向，采用树脂砂造型，使用球化剂 C-6A、孕 育剂 YF-150 进行处理，将 Si 含量控制在 3。3%~4。1%、 CE 控制在 4。5%左右， 同时控制其他合金元素的含量，如 S、Mn、P、Re、Mg 等。最终浇注 120mm、 180mm、240mm、300mm 的球墨铸铁试块，综合分析试块的金相和力学性能。 研究总结高 Si 球墨铸铁的特性及高 Si 对厚大断面铸件的影响。同时结合实验中

出现的石墨形态、低温冲击问题，提出改进工艺，期望可以生产出符合要求的 QT500-14，这对行业内生产高强高韧性球墨铸铁具有十分重要的理论价值和实 践意义。

毕业论文关键字：球墨铸铁；Si 固溶强化；工艺设计；试块性能

Abstract China is the largest producer of cast iron, the growth rate of ductile iron production becomes excessively fast since entering the 21st century。 Because of ductile iron with excellent propety and low cost, it has been used widely in various industrial fields。 The ductile iron with high strength and tenacity is one of the most promising, it gives material a higher mechanical properties and process performance。 The paper introduces excellent properties of high tough ductile iron, current Studies and prospect on that, especially introduces the effect of Si element on ductile iron, and the superiority of Si solid solution strengthening on ductile iron, at the same time, the feasibility of high Si ductile cast iron is discussed。

In the paper, we choose QT500-14 as the experimental direction, furan resin sand molding process was used, Treatment with the nodulizer of the C-6A and inoculation of YF-150, control the Si content in the range of 3。3%~4。1% and CE in about 4。5%, at the same time, control the content of other alloy elements Such as S, Mn, P, Re, Mg,

etc。 Finally casts were poured out that wall thickness of test block were 120mm、

180mm、240mmand300mm。 I did a comprehensive analysis on metallographic and mechanical properties of the test block。Later the characteristics of high Si ductile cast iron and the effect of high Si on heavy section castings are studied。 At the same time, the improved process was put forward based on the shape of graphite and the impact of low temperature。 Hope that the material of QT500-14 can be produce。 It has very

important theoretical value and practical significance to produce high strength and high toughness ductile iron in the industry。

Key words: Ductile iron; Si solution strengthened; Process design; Test block property

目 录

第一章 绪论 1

1。1 引言 1

1。2  球墨铸铁 1

1。2。1 球墨铸铁概述 1

1。2。2 球墨铸铁的生产工艺 3

1。2。3  球墨铸铁的研究现状 4

1。3 Si 在球墨铸铁中的作用 5

1。3。1 Si 促进石墨化 5

1。3。2 Si 在基体中的固溶强化作用 6

1。3。3 Si 的孕育形核作用