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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 low temperature impact toughness of nodular cast iron, starting from 4 aspects of chemical composition, matrix structure, graphite structure and preparation process, the as-cast microstructure of low-temperature nodular cast iron consists of spheroidal graphite, ferrite, pearlite and a small amount of cementite. The amount of pearlite in as-cast samples increases with the increase of nickel content and decreases with the increase of silicon content. After the graphitizing annealing heat treatment, the amount of pearlite in the sample is reduced, the amount of ferrite is increased, and the cementite is completely eliminated. In order to ensure the use of castings at low temperatures, will not occur brittle fracture.