EXCIMER-LASER USED AS A MATERIALS CHARACTERIZATION TOOL - SULFIDE INCLUSION PRINTING IN STEEL

An application of the excimer laser in the area of material characteri zation making use of its ablative ability to perform surface sulphur p rinting is presented. It is shown that the differential ablative and s urface melting capability of the excimer laser is useful in microetchi ng sulphide inclusions in flat polished steel samples and rough fractu re surfaces. An optimum laser fluence is found to be that which melts the sulphide particles without significant melting of the steel matrix or causing overlap of the characteristics halo formed by the out-flow ing liquid from the sulphides. The geometric similarity of the sulphid e inclusions is maintained and its spatial extent is amplified about 1 0 times. This brings sub-micron sulphide particles into optical resolu tion range. The liquid wetting behavior of the sulphide liquid is vari able with Mn/Fe ratio and determines the extent of the halo formation.