灰铸铁件加工面麻点状小孔缺陷的分析及防止

Analysis and Prevention of Pocked Spots Defect on Cutting-Machined Surface of Gray Iron Casting

采用金相方法对HT300铸件加工面麻点状小孔缺陷的形貌、分布特征和产生原因进行了分析。认为:麻点是由许多尺寸在0.3mm以下的小孔组成,多产生在凝固过程中冷速较慢的厚壁部位,主要分布在石墨密集区域,特别是在石墨封闭或半封闭区域;铸件w(C)和w(Si)量偏高,凝固过程中局部冷速过慢,切削用量偏大都有可能引起这种缺陷。提出了预防这种缺陷的四条措施。

By using metallographic method, the morphology, distribution feature and formation reason of the pocked spots-shaped pinholes on the machined surface of HT300 grade gray cast iron casting was analyzed. It was considered that the pocked spots are actually many small pinholes sized less than 0.3 mm, they are normally existing in the heavy section area which cooling relatively slowly during solidification process, and mainly in the graphite-dense area, especially in the area enclosed or nearly enclosed by grap...