Experiment study on the corrosion resistance of the surface metamorphic layer of grindingComments Off on Experiment study on the corrosion resistance of the surface metamorphic layer of grinding
Workpiece will face corrosive problems during its application after the manufacturing process. As the common final process, grinding can generate special metamorphic layer on the surface of workpiece and change the initial corrosion resistance of workpiece. In order to study the corrosion resistance of workpiece after grinding process, the paper carries on combining experiment of grinding and electrochemical corrosion. The characteristic of corrosion resistance of grinding is revealed based on the association of grinding mechanism and electrochemical theory. The corrosion potential of workpiece after grinding is higher than matrix, which shows the grinding surface is difficult to begin to corrode. Electrochemical impedance spectroscopy (EIS) shows the grinding surface has large phase angle, impedance and capacitance characteristic because the metamorphic layer of grinding has good obstructive ability. They reveal that grinding improves the surface corrosion resistance of workpiece. Then the mechanism of the corrosion resistance of grinding is revealed. The special grain boundary formed in grinding with much C element, large clusters and complex shape prolongs the corrosion channel, which reduces the corrosive speed. While, the sensitive hardening structure generated in grinding hardening with much free energy is easy to form the corrosion cell, which will accelerate the corrosion.
Grinding is always the final procedure in the manufacturing process, which will decide the final characteristic of surface layer and its surface integrity of the workpiece. So the grinding has a key meaning to technology level of the modern equipment manufacturing1,2,3. Before the grinding process, the workpiece is always machined by all kinds of cutting process, such as the turning, milling, boring and planning. Therefore, the grinding, on the one hand, needs to lower the machining errors of the former process and increase the machining precision of workpiece, then needs to obtain the high quality of surface integrity in the surface layer during the process on the other hand4,5,6,7. Grinding uses the abradant to remove the materials of workpiece. The grinding wheel has a large linear velocity and the strain rate of the processed material is large8,9. Combining with the cutting effect with large numbers of abrasive grain, large grinding force and high grinding temperature are generated during the grinding process, adding the factors of mechanical vibration.
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