一、绪言 我厂与华中工学院合作,首先采用1~#稀土硅铁对碳当量Ce=3.9～4.05％冲天炉铁水进行孕育处理试验,并与相同碳当量75硅铁的孕育铸铁进行比较,证明了稀土（Re）对提高灰铸铁机械性能和减小断面敏感性的有利作用。在此基础上我们于八四年开始研制一种以稀土为主要成份,包含Cr、Cu等合金元素的复合孕育剂代替传统的75硅铁,以期获得既有良好铸造性能,又有较高机械性能和组织均匀性的铸铁,以满足生产发动机缸体缸盖等复杂薄壁高强度铸件的要求。 生产试验在南柴厂进行,孕育后铁水直接用来浇注缸体缸盖。大量数据分析结果表明,稀土复合孕育剂孕育的灰铸铁较75硅铁孕育灰铸铁,机械性能有明显提高（约2～4公斤/毫米~2）,而且在较高碳当量（即Ce=3.90～4.2％）时,抗拉强度乃能稳定达到HT25-47牌 First, the introduction I plant and Huazhong Institute of Technology, the first use of 1 ~ # rare earth ferrosilicon carbon equivalent Ce = 3.9 ~ 4.05% cupola hot metal inoculation test, and with the same carbon equivalent of 75 ferrosilicon ferroalloy pregnant were compared, The beneficial effects of rare earth (Re) on improving the mechanical properties and reducing the sensitivity of the gray cast iron have been proved. On this basis, we started in 1984 to develop a rare earth as the main ingredient, including Cr, Cu and other alloying elements composite inoculant instead of the traditional 75 ferrosilicon, in order to obtain both good casting performance, but also a higher mechanical Performance and homogeneity of the cast iron to meet the production of engine cylinder head and other complex thin-walled high-strength castings requirements. The production test was carried out in Nanchai Plant, and the hot metal was used to pour the cylinder head directly. The results of mass data analysis showed that the mechanical properties of gray cast iron inoculated with rare earth composite inoculant were significantly improved (about 2 ~ 4 kg / mm ~ 2) compared with that of 75 ferrosilicon, ~ 4.2%), the tensile strength can reach HT25-47 steadily