Gray cast iron etchant: 4% nitric acid alcohol solution microstructure: ferrite+flake graphite

    Firstly, it should be clarified that the scratches on the ferrite are caused by the damage layer during the sample cutting process. In the preparation process of cast iron metallographic samples, it is necessary to first remove the damaged layer caused by cutting. If using a band saw or electric tool, the damage layer generated is much deeper than the damage layer generated by using a metallographic grinding wheel cutting machine. The first step of rough grinding must remove these damage layers caused by cutting.

    Coarse QMAXIS metallographic sandpaper is effective in removing metal damage layers, but it should be noted that each step of the metallographic sandpaper grinding process produces new damage layers, which are gradually removed through subsequent polishing steps.

    If scratches are found on the ferrite structure before polishing, a small diamond polishing solution can be used to remove these scratches; Of course, aluminum oxide polishing paste can also be used to remove it. If there are still small scratches after mechanical polishing, Electropolishing can be selected to remove the small scratches generated during mechanical polishing. However, if the scratches are deep, it is necessary to return to the polishing step using coarse QMAXIS metallographic sandpaper.

    Many metallographic engineers prefer to use erosion in the final step of sample preparation& Flash; Polishing&ndash& Flash; Erosion is such a preparation method that sometimes a sample may even be prepared multiple times using this method. This method is very beneficial for removing plastic flow and small scratches in the metal, but it also exacerbates embossing and sample edge rounding. Here, QMAXIS does not recommend using this step multiple times.