灰铸铁类(包括高磷铸铁、硼铸铁等)汽缸套加工后常因内表面出现多量针孔而报废。业经确定,针孔的成因和种类是多样的,如夹渣和缩松都可产生针孔。它的主要特征是比较均匀地分布于整个缸套内表面,有时大端内表面分布得多些。此种针孔较细,大多小于0.2mm。由于这种针孔有时在缸套大端内表面(热节处)分布得较多,且孔底有金属光泽,与缩孔的宏观特征有某些相似之处,因此不少人认为它是缩松孔。也有人根据其分布于整个汽缸套内表面的特征(这个特征不同于疏松,疏松一般只出现在热节处)认为它是石墨脱落孔。我们曾对此种针孔进行了系统的分析,查明其为基体剥落针孔,并找到了消除这种针孔的方法 Gray cast iron (including high-phosphorus cast iron, boron cast iron, etc.) Cylinder liner processing often because of the inner surface of a large number of pinhole and scrapped. Industry has identified pinhole causes and types are diverse, such as slag and shrinkage can produce pinholes. Its main feature is more evenly distributed throughout the cylinder liner surface, and sometimes larger end of the inner surface is more distributed. This pinhole smaller, mostly less than 0.2mm. Since such pinholes are sometimes more distributed on the inner surface of large-diameter cylinder end (hot joints) and have a metallic luster at the bottom of the cylinder and have some similarities with the macroscopic features of the shrinkage cavities, many people think that it is Shrinkage hole. It is also based on its distribution in the entire cylinder liner on the surface of the characteristics (this feature is different from loose, loose generally only appear in the hot section) that it is graphite off hole. We have conducted a systematic analysis of such pinholes and found them to be exfoliated pinholes and found ways to eliminate such pinholes