耐热球铁中碎块状石墨的产生机理及防止措施

结合生产实践中铁液过冷度对石墨形核的影响,研究了耐热球铁中的碎块状石墨产生机理。结果表明,耐热球铁中热节部位极易出现碎块状石墨,而导致这种碎块状石墨出现的主要原因为铁液凝固过程中具有较高的局部成分过冷。提高铁液活性、控制CE及微量元素成分、选取合适的孕育剂和孕育方式、提高局部冷却速度、减少铸件热节等工艺方案可以有效防止耐热球铁中的碎块状石墨产生问题。

Formation Mechanism and Prevention Measures of Chunk Graphite in Heat-resistant Nodular Iron

Based on the effect of the degree of hot metal supercooling on the graphite nucleation in production practice,the mechanism of the formation of chunk graphite in heat-resistant nodular iron was studied.The results show that the thermal centers of heat-resistant ductile iron are prone to the occurrence of chunk graphite,and the main reason for the occurrence of such chunk graphite is that the molten iron has high local component undercooling during the solidification process.Improving the activity of molten iron,controlling the composition of CE and trace elements,selecting the appropriate inoculation agent and inoculation method,increasing the local cooling speed and reducing the hot section of casting can effectively prevent the problem of chunk graphite in heat-resistant nodular iron.