Influência da microestrutura na usinabilidade do ferro fundido nodular FE45012 em diferentes bitolas, obtidos por fundição contínua

Abstract

The present work evaluated the behavior of machinability along the cross section of nodular iron bars produced by continuous casting in different gauges. The gauges studied were cylindrical and rectangular . Throughout the experiments, tests were performed to characterize the materials and machining trials . For the characterization tests of the materials were analyzed hardness, microstructure , stretching, necking , yield and tensile strength over the cross section of the samples. In the machining tests, the samples were subjected to the processes of drilling, turning and milling. The parameters evaluators in these trials were: evolution of tool wear, tool life , machining forces , torque, power and surface roughness . All tests were performed at the Laboratory for Education and Research in Milling of the Faculty of Mechanical Engineering , Federal University of Uberlândia (LEPU/UFU) . The results showed no statistical difference in the feed force machinability during tests with constant pressure to the gauges with diameter 53 mm . As for the gauges circular with a diameter of 156 , 203 and 421 mm and the rectangular gauges , statistical differences between the regions of the nucleus and the intermediate zone . For the results of the depth of the hole during the drilling with constant pressure , the gauges with diameters of 156 and 203 mm , presented , regardless of the machining parameters used statistical difference between the regions of the nucleus and the intermediate zone . The samples of gauge 421 mm diameter and rectangular statistical differences between all regions . In tests turning and milling , it was found increased levels of wear on the tools usinaram the core region in relation to the tools usinaram region of the periphery. There was a tendency , when turning , the machining force increase when the region shifted from the periphery toward the nucleus in circular gauges . No difference was observed between the machining power regions of the gauges used during the milling process . All gauges feature circular roughness Ra statistical difference between the regions of the core and the periphery . There was no statistical difference in roughness between regions during milling .