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前言在球墨铸铁中,降低含硅量可以提高常温冲击韧性和降低脆性转化温度,这一规律早已被人们所共知[1][2]。同时近年来对石墨球的尺寸的控制亦逐渐引起人们的注意,因为它无论对球铁的静强度性能及疲劳性能都有一定的影响[3]。但是在国内球墨铸铁的实际生产条件下,作为球化剂的稀土合金或稀土镁合金中皆含有较高的硅,尤其是大多数工厂为了消除铸态组织中的自由渗碳体,一般皆采用大剂量孕育或多次孕育工艺,因此使铁水的最终含硅量大多在2.5%左右或更高。所以生产球铁的工厂都对原料生铁提出了低硅的要求。至于列石墨球尺寸的控制以及它对球铁机械性能的影响,则尚注意得较少。
Preface In the ductile iron, reducing the silicon content can increase the impact toughness at room temperature and reduce the brittle transition temperature, the law has long been known [1] [2]. At the same time, the control of the size of graphite ball has drawn more and more attentions in recent years because of its influence on the static strength and fatigue performance of the ductile iron [3]. However, under the actual production conditions of domestic ductile iron, the rare earth alloy or rare earth magnesium alloy which is a nodulizer contains high silicon, especially for most factories, in order to eliminate the free cementite in the as-cast structure, it is generally adopted High-dose inoculation or multiple inoculation process, so that the final content of molten iron silicon content of about 2.5% or more. Therefore, the production of ductile iron plants have proposed low-silicon raw material requirements. As for the control of column graphite ball size and its effect on the mechanical properties of ductile iron, less attention is paid.