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蠕墨铸铁是一种所含石墨的形状介于片状和球状之间的高强度、有发展前途的新材料。它与孕育铸铁相比具有强度高,塑性、韧性好,抗氧化,抗生长能力强,壁厚敏感性小等优点,与球墨铸铁比较具有铸造性能好,铸件收得率高,热膨胀系数低,导热性、热疲劳抗力高,高温工作时尺寸稳定性好,减震性好等优点。国内近十几年来已将它用于生产发动机缸套、液压件、水泵叶轮、进出水段以及机床床身、工作台等铸件。一、试验情况用蠕墨铸铁生产壁厚约为10mm铸件的主要矛盾是容易形成白口。近年来也有解决这方面问题的经验,如用含一定量Ti的稀土镁钛(Re—Mg—Ti)蠕化剂,适宜于大量生产薄壁蠕铁件。但长期应用含Ti蠕化剂,容易造成Ti的积累,污染回炉料。也有资料介绍加Ca的稀土合金蠕化剂有利于薄壁铸件获得无白口组织。但Ca的吸收率低,加入量多,形成的浮渣多。所以,就存在Ca的合理加入量问题,使薄壁件既不产生白口,而“浮渣少”、蠕化率较高。
Compacted graphite cast iron is a kind of graphite containing shape between the sheet and the ball of high strength, promising new materials. Compared with inoculated cast iron, it has the advantages of high strength, good ductility, good plasticity, toughness, strong anti-oxidation, strong anti-growth ability and small wall thickness sensitivity. Compared with ductile iron, it has better casting performance, higher casting yield and lower thermal expansion coefficient, Thermal conductivity, high thermal fatigue resistance, high dimensional stability when working, good shock absorption and so on. Over the past decade it has been used for the production of engine cylinder liner, hydraulic parts, pump impeller, out of water and machine bed, table and other castings. First, the test situation With compacted graphite cast iron production wall thickness of about 10mm cast the main contradiction is easy to form white. In recent years, there are also experiences in solving this problem. For example, Re-Mg-Ti vermiculite containing a certain amount of Ti is suitable for mass production of thin-walled vermicular iron. However, long-term use of Ti-containing vermiculite, Ti can easily lead to the accumulation of pollution back to the charge. There are also information on the introduction of rare earth alloy Ca plus vermiculite is conducive to thin-walled castings to obtain no white tissue. However, the absorption rate of Ca is low, adding more, the formation of scum and more. Therefore, there is a reasonable amount of Ca added to the problem, so that the thin-walled parts do not produce white mouth, and “less scum”, high rate of vermicular.