The effect of the module to microstructure and mechanical properties in the production of spherical graphite cast irons

In this thesis, GGG70L material, which is a spherical graphite cast iron alloy, has been used. Model A was cast to rectangular prism shaped models with dimensions of 100 mm x 100 mm x 300 mm, model B 50 mm x 50 mm x 300 mm and model C 25 mm x 25 mm x 300 mm. Module values of the models were calculated. The effects of the change in the module value on the microstructure and mechanical properties of the material were investigated. In the size of C model samples were removed from A and B model and the effects of modulus change on hardness, tensile and microstructure were investigated. First the samples were subjected to polishing and then etching. After the microstructure investigations of the samples were taken, photographs were taken from the images taken. Afterwards, image analysis was performed. Sphericalization of samples before etching, mean sphere diameter and percentage distribution of spheres; Microstructure analysis and percentage phase distribution were determined after the samples were etching. Finally SEM examinations of the samples were made. As a result of the study, the expected results were reached. It has been determined that the chemical composition of the casting material confirms to the standards. As the module size decreased, tensile strength, yield strength and % elongation values were determined to decrease. It was determined that the hardness increased in an inverse proportion to the decrease of the module size. It was determined that the sample with low module value had a smaller sphere diameter due to faster cooling. It was observed that the sample with smaller module value solidified more rapidly and the number of spheres over to mm2 was increased in parallel. It has been observed that the amount of sphericity and % sphericity graphite increase as module value decreases. It has been found that the change of the module does not directly affect the phase change in the structure and it is seen that the changes in the phase analysis are affected by the chemical composition of the existing samples.