中文摘要：

利用本地丰富的钇基重稀土合金处理铁水,探讨高温条件下灰铸铁、蠕墨铸铁和球墨铸铁的石墨组织和力学性能,同时用数理统计的方法推导出它们的线性膨胀系数回归方程.结果表明：高温下三种铸铁的断裂破坏特性分别为解理断裂、准解理断裂和韧窝断裂.同时证实了球墨铸铁具有比灰铸铁和蠕墨铸铁高得多的高温抗拉强度;蠕墨铸铁具有较优良的综合高温耐热性能,尤其是伸长百分率和耐热疲劳性要大大优于灰铸铁;球墨铸铁和蠕墨铸铁相变前的线性膨胀系数比灰铸铁低而且保持相对稳定.同时它们具有比灰铸铁低得多的相变收缩率.

英文摘要：

In this paper, local rich resources of yttrium base heavy rare earth was used to treat molten iron. Graphite structures and mechanical properties of gray cast iron, compacted graphite cast iron and ductile cast iron were studied under condition of high temperature. And their linear regression equation for expansion coefficient were proposed age, quasi cleavage and dimple fracture cast iron and ductile cast iron. Moreover The results showed that their fracturing properties were cleav- in high temperature for gray cast iron, compacted graphite it was confirmed that high temperature tensile strength of nod- ular cast iron is much stronger than that of gray iron and compacted graphite cast iron. Compacted graphite cast iron has excellent comprehensive high temperature resistant performance, and especially the elongation percentage and thermal fatigue resistance is much better than that of gray cast iron. Lin- ear expansion coefficient before phase change of ductile cast iron and compacted graphite cast iron were lower than that of gray cast iron and remained relatively stable, and they has the phase change contraction ratio much lower than that gray cast iron.