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

Abstract

An application of the excimer laser in the area of material characterization making use of its ablative ability to perform surface sulphur printing is presented. It is shown that the differential ablative and surface melting capability of the excimer laser is useful in microetching sulphide inclusions in flat polished steel samples and rough fracture 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-flowing liquid from the sulphides. The geometric similarity of the sulphide inclusions is maintained and its spatial extent is amplified about 10 times. This brings sub-micron sulphide particles into optical resolution range. The liquid wetting behavior of the sulphide liquid is variable with Mn/Fe ratio and determines the extent of the halo formation.