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本文研究了球墨铸铁奥氏体化过程,基体含碳量、不同断面试样加热和冷却时的温度分布以及各种正火工艺的机械性能结果表明:球铁的奥氏体转变过程很快,奥氏体转变刚结束时,基体含碳量较低,约为0.55-0.65％,保温使基体继续增碳直到饱和。不同断面试样表面和中心温度差随温度升高而减小。当铸件表面达850℃以上时,温差可以忽略。因此。没有必要为使工件温度均匀化而保温。同时试验结果并发现:保温对改善机械性能并无作用,但提高冷却速度可显著提高机械性能,特别是对于直径小于120毫米的工件更为有效。
In this paper, the austenitization process of ductile cast iron, the carbon content of the matrix, the temperature distribution during the heating and cooling of different cross-section specimens and the mechanical properties of various normalizing processes were studied. The results show that the ductile iron has a rapid austenite transformation process, At the end of the austenite transformation, the carbon content of the matrix is relatively low, about 0.55-0.65%, so that the matrix continues to increase carbon until saturated. The temperature difference between the surface and center of specimens with different cross sections decreases with the increase of temperature. When the casting surface of more than 850 ℃, the temperature difference can be ignored. therefore. It is not necessary to keep the temperature of the workpiece uniform. At the same time the test results also found that: Insulation has no effect on the improvement of mechanical properties, but increasing the cooling rate can significantly improve the mechanical properties, especially for the workpiece diameter less than 120 mm more effective.