Metallographic Microscope is used for inspection of the micro structure for gray iron and ductile iron castings. The crystal structure is inspected (nodularity), this to ensure the strength and material quality of desired material standard.
Frequently used standards are:
EN GJS 400-15, also know as GGG40, QT 400-15
EN GJS 500-7, also know as GGG50, QT 500-7