Papers by Author: Xiang Ming Huang

Abstract: Ground white layer is caused primarily by grinding temperature induced phase transformation. So, it may form when grinding temperature exceeds the nominal phase transformation temperature. However, no attempt is made to investigate mechanical effect on formation of white layer. In this study, grinding temperature is measured by using thermocouple technique in grinding of AISI 52100 annealed steel. The specimens are investigated by using scanning electron microscope (SEM), energy disperse spectroscopy (EDS), micro hardness tester and X-ray diffraction (XRD). The microstructure and formation mechanism of white layer are analyzed. Ground whiter layer is confirmed to be composed of fine-grained cryptocrystalline martensite and retained austenite. High hardness of white layer is caused by transformation hardening through fine grain and high dislocation density due to severe deformation. White layer can form at temperatures below the nominal austenitization temperature of the material. Plastic deformation is also important in white layer formation during grinding process. High pressure on grinding surface exists under severe deformation. Phase temperature can be reduced due to high pressure; while crystal grain can be refined by plastic deformation. Oxidation and carburizing phenomenon exist during formation of white layer.

Abstract: White layers formed in grinding process have negative effects on components. White layer will result in brittle surfaces, which will cause product failure. Since grinding parameters may influence white layer formation, it is necessary to study the relationship between white layer thickness and various grinding parameters. In this study, grinding experiments are carried out using harden AISI52100 steel as work material. Grinding parameters，such as wheel speed, workpiece speed, grinding depth, grinding wheel wear and cooling condition on the thickness of white layer have been studied. The specimens were analyzed using a micro hardness tester and SEM. The experiments indicate white layer depth varies with the different combinations of machining parameters. The depth of white layer increases with the grinding depth, wheel speed and wheel wear. There is a critical work table