The Effects of Sandblasting on the Surface Properties of Magnesium Sheets: a Statistical Study

In the present study, the effects of sandblasting on the surface properties of magnesium (Mg) sheets were investigated. A 32 Central Composite Design (CCD) of Experiments was developed and applied to attain reliability, reproducibility, and significance of the experimental results. Following the CCD, pressure and application distance were selected as factors (experimental variables), whereas the surface roughness, hardness, and corrosion current were measured as the response variables (surface properties). Three effects of the factors were studied (pressure change, distance change, and their combined change) through an Analysis of Variance. The charts of the main effects showed that in the case of roughness and corrosion current, the three effects are significant to their modification, i.e., they increase by raising any of the factors or both at the same time. On the other hand, only the pressure is significant for the modification of hardness, this means that hardness can be improved by increasing the pressure, regardless the application distance. Also, it was found that pressure is the key factor for the modification of roughness, hardness, and corrosion current, accounting for a contribution of 57.0%, 72.8%, and 61.0%, respectively. The microstructural analysis showed that sandblasting produces a grain refinement and leaves a deformed crystalline structure in a subsurface layer. Also, for high pressures and short application distances defects such as cracks and voids are generated on the surface. All these microstructural changes correlate to the modification of the surface properties.