The sample is taken from the edge, 1 / 2R and center of lzqt600-3profile. It is first polished by coarse to fine sandpaper, and then polished. It is necessary to ensure that there is no scratch on the metallographic surface of the sample. During polishing, the suspension composed of chromium trioxide and a small amount of chromic anhydride is used as the polishing solution. During corrosion, it is eroded with 4% nitric acid alcohol solution for 10 ~ 15 s, washed with absolute ethanol and dried by cold air. The microstructure was observed by 4xc optical microscope before and after corrosion. The number of graphite balls, equivalent diameter and average shape factor of graphite balls were statistically analyzed by Image J software on the surface of edge, 1 / 2R and center samples before corrosion. Image J was also used for edge, 1 / 2R and center samples after corrosion The content of pearlite and the distance between pearlite lamellae were analyzed by software.
The image J software can realize this function. The software supports various plug-in technologies. According to the user’s own needs, it can also write various Java language geometric feature analysis programs. In the selected region, a series of geometric features of the object to be analyzed are obtained by Image J software. For nodular cast iron, the morphology of graphite and the number of graphite balls have significant influence on the mechanical properties of nodular cast iron. The number of graphite balls, spheroidization rate and pearlite content are generally used to characterize the microstructure of ductile iron. Therefore, Image J software is used to quantitatively analyze the number of graphite balls, spheroidization rate, equivalent diameter, shape factor and pearlite content of different parts (edge, 1 / 2R, center) of horizontal continuous casting lzqt600-3 ductile iron profile, and objectively describe the as cast microstructure characteristics through data.