Surface melting of AlSi10Mg with Co2 laser radiation

The melting of sandcast and chillcast AlSilOMg alloys with CO2 laser radiation is investigated as a fuction of processing variables to improve the surface properties with respect to wear resistance by self-quenching and rapid solidification. To overcome the high reflectivity of aluminium alloys graphite coatings were used to increase the energy coupling. In order to avoid any chemical reactions with the ambient, shielding gases such as CO2, He, Ar, and N2 have been used. The results of microstructural refinement are discussed in view of processing variables, melt dynamics, improvement in wear and efficiency of energy coupling in combination with calculations of the processing geometry via diffusive and convective heat transfer.