Laser surface melting of cast iron containing undercooled graphite

Laser surface melting experiments were carried out on an alloy cast iron with 3% C, 2% Si and 0.25% Ti containing undercooled graphite. Different heating times and energy densities were used to achieve different penetration depths and cooling rates. The microstructures obtained after surface melting and after various heat treatments are presented and discussed. It is shown how the cooling rate and concentration influence the solidification behaviour of high carbon cast irons. The composition chosen for the experiments can be considered as representative of many cast irons.--AA