低温环境下提高球墨铸铁冲击韧度的方法

Method to Improve Impact Toughness of Ductile Iron in Low Temperatures

提高球墨铸铁低温冲击韧度,要从化学成分、基体组织、石墨组织、制备工艺4个方面着手,低温球墨铸铁的铸态组织由球状石墨、铁素体、珠光体及少量渗碳体组成。铸态试样的珠光体量随镍量增加而增加,随硅量的增加而减少。石墨化退火热处理后,试样珠光体量减少,铁素体量增加,渗碳体完全消除。从而保证铸件在低温环境下使用时,不至于发生脆性断裂。

To improve the impact toughness of ductile iron in low temperature from the four aspects of the chemical composition, the matrix microstructure, the graphite morphology, and the preparation process. The as-cast microstructure of low temperature ductile iron consists of spherical graphite, ferrite, pearlite and a small amount of cernentite. The pearlite amount in as-east specimens increases with the increase of the content of nickel, while decreases with the increase of the content of silicon After graphitization annealing heat treatment, the amount ofpearlite in sample reduces, the amount of ferrite increases, the cementite eliminates completely to prevent castings from brittle fracture in low temperature environment.