Selection of raw materials and control of trace elements for production of high-quality SG iron

摘要

During the production of SG iron, the selection of raw materials and control of chemical compositionare most important. From the very early days of SG iron production, the effects of trace elements on graphite formand matrix structure have been studied, and the allowable concentration limits for their detrimental influence hasbeen decreased year by year, during the last fifty years. This paper has reviewed some of the suggested SG irontrace elements in the literature and in several Chinese foundries. It was found that for most SG iron castings, rareearth elements are still required to neutralize the harmful effects of trace elements and improve SG iron quality. Italso found that the use of high purity and ultra-high purity base iron melts enabled integrated, safety-critical andcomplicated SG iron castings of varying thickness, and heavy-section, to be produced successfully. These SGiron castings have surprisingly good structures, and their mechanical and dynamic properties are vastly superiorto those specified in current international SG iron standards. Further study is required on the effects of using highpurity and ultra-high purity base melts on the structure and properties of SG iron.