冷激铸铁凸轮轴“黑线”缺陷的产生原因和消除措施

Formation Reason and Elimination Measures of "Black-Line" Defect of Chilled Cast Iron Camshaft

对冷激铸铁凸轮轴的"黑线"缺陷进行显微分析发现,缺陷区的基体组织为珠光体,石墨形态为枝晶点状石墨。对缺陷的产生原因和机理进行了探讨,认为是凝固前沿不断得到释放出的结晶潜热,产生"热量积累",导致凝固前沿温度重新升高,高于凝固前沿介稳定共晶温度以后,冷速变慢产生的灰口组织;提出了防止"黑线"缺陷产生的措施。

The ＂black line＂defect found on chilled cast iron camshafts was analyzed metallographically and found that the microstructure of defect zone consisted of pearlitic matrix and D-type graphite. The reason causing black line defect and its formation mechanism was discussed, and measures to prevent defect formation was proposed.