磺酸自硬砂引起球铁件表层异常组织的研究

A Study of the Abnormal Structure at the Surface Layer of Nodular (SG) Iron Castings Produced by Sulfonic Acid Cured Sand Mold

通过实验研究,用甲苯磺酸作催化剂的呋喃树脂自硬砂与稀土镁作催化剂生产的球铁件,通常在其铸件表层出现异常组织。提出导致异常组织产生的原因,同时又降低了试件的冲击值,并且采用反应型或屏蔽型涂料将可防止球铁件表层异常组织缺陷,为生产性能良好的球铁件提供技术依据。

By analyzing the result of the experiment, it reveals that the abnormal structure usually appears at the surface layer of nodular iron castings produced by furan-sulfonic acid, toluene sulfonic acid （TSA）, cured sand mold with the nodulizing agent, Mg-RE alloy. It shows that the abnormal structure （graphite flakes in a ferrite-rich matrix） is caused by the evolution of sulfur dioxide （SO2） with TSA during casting and solidification. It is found that the abnormal structure can be prevented by using such particular mold coating materials as the reactive or the protective type, which provides technical support of nodular iron casting.