SEM and TEM microstructural investigation of high-speed tool steel after laser melting

The microstructure of a continuous CO2 laser-melted high-speed steel, namely M2, has been studied. The formation of the microstructure under rapid solidification conditions is described by means of scanning electron microscopy, transmission electron microscopy and energy-dispersive X-ray spectroscopy. A very fine dendritic structure is characteristic for the microstructure formed under such rapid solidification conditions like laser melting. This structure generally consists of fine dendrites of austenite crossed by a very fine carbide network or the eutectic without the primary large carbides. The structure obtained in the surface layer after laser melting permits to get a high level of hardness and shows an improved wear resistance.