The Influence of Milling Parameters on Surface Properties in Milled AZ91C Magnesium Alloy

A full factorial design of experiment was applied in running 36 experiments to investigate the effect of milling parameters including cutting speed, feed rate, cutting depth and machining media at two levels, on surface integration properties of magnesium AZ91C alloy such as grain size, secondary phase content, surface microhardness and roughness. In all cases, a fine grained surface with higher secondary phase sediment and microhardness was obtained in comparison to the raw material. According to analysis of variance results, the most effective parameter on grain size, secondary phase percent and microhardness was cutting depth and the most effective parameter on surface roughness was the feeding rate. although the grain size in all machined samples was smaller than that of the raw material but due to the dual effect of cryogenic conditions, which both cool and lubricate and reduce the temperature and strain rate at the same time, the direct effect of this parameter on grain size was not significant. The collective effect of parameters on grain size and microhardness was also significant.