Since the free carbon in gray cast iron is in flake form, the gray cast iron is also called flake graphite cast iron. The existence of the flake graphites make gray iron almost without any ductility, thus gray iron is a typical brittle metal. However, there are still many industrial applications. For brittle material, the compression fracture load is 1/ν, of the tension fracture load, i.e. F{sub}(fracture, compression) = 1/ ν F fracture, tension, where ν : Poisson's ratio. The purpose of this research is to determine the range of the aspect ratio (H/D, Height/Diameter) within that the above equation is valid. It was found that, for H/D = 0.5～3.0, actual test data were within 13.1% variation from the theoretical data, especially for H/D = 2.5 where the difference between the tested and the calculated data was only 3.4%. When grease was used for lubrication, the applicable range of the aspect ratio was increased (0.5～4.0), while the error was increased to 15.8%. When machine oil was applied, although the error was reduced to 11.1%, the applicable range of the aspect ratio became narrower (0.5～2.0). All the fracture surfaces of the compressive fractured specimens are similar to those of the tensile test specimens, exhibiting a cleavage brittle fracture morphology.
Gray cast iron Aspect ratio Lubrication Compressive fracture