Enhanced functional properties of Mg alloys by cryogenic machining

Surface integrity of manufactured components has a critical impact on their functional performance. Magnesium alloys are lightweight materials used in the transportation industry and are also emerging as a potential material for biodegradable medical implants. However, the unsatisfactory corrosion performance of Mg alloys limits their application to a greater extent. Surface integrity factors, such as grain size, crystallographic orientation and residual stress, have been proved to remarkably influence the functional performance of magnesium alloys, including corrosion resistance, wear resistance and fatigue life. In this paper, the influence of machining conditions, including dry and cryogenic cooling (liquid nitrogen was sprayed to the machined surface during machining) on the surface integrity of AZ31B Mg alloy was investigated. A finite element study was conducted for machining of AZ31B Mg alloy. A model was developed and incorporated to predict the temperature distribution within the workpiece and chip during machining in different conditions. Good agreements between the predicted and measured temperature distribution in the literature. Cryogenic machined samples are found to have greater surface finish in comparison with dry machined samples. Further, maximum temperature rise at the surface during machining during cryogenic machining was lower than in the case of dry machining. © Research India Publications.