High intensity laser effects on stainless steel in a vacuum

The interaction of AISI 304 stainless steel with an intense Q-switched neodymium-doped yttrium aluminium garnet laser beam (λ=1.06 μm) was studied in an ultrahigh vacuum system using Auger electron spectroscopy and quadrupole mass spectroscopy. Laser etching of the sample was observed and a comparison was made with the ion-etching profile of the same sample. Owing to the selective evaporation of oxygen from the liquid layer of stainless steel produced by the laser irradiation, an ultrathin film of elemental iron was formed on the underlying oxide. Moreover diffusion of chromium from the bulk to the surface occurs, which cannot be accounted for by the segregation mechanism that has been proposed to account for surface segregation in some ion-implanted materials.