Plasma-facing components in tokamak-type fusion reactors are subjected to intense heat loads during plasma disruptions. The influence of high heat fluxes on the depths of heat-affected zones on Type 316 stainless steel with different sulfur impurities was studied for a range of energy densities and disruption times. It was demonstrated in small beam simulation experiments that under certain conditions, impurities through their effect on surface tension create convective flows, hence exercising a determining influence on the flow intensities and the resulting depth of molten layers. When a CO2 laser is used as a heat source, the role of impurities diminishes, due to high temperatures on the surface of the specimens, and all types of stainless steel behave like pure material. However, by using an alternative heat source that produces lower surface temperatures, e.g., tungsten inert gas, the stainless steel containing high sulfur produces much higher melting zone thicknesses compared with the low sulfur steels. Comparison between experimental results and existing theoretical predictions reveal significant differences in the depths of the melt layers.