Laser cleaning of steels after high temperature oxidation

Abstract

Summary form only. In the present work, the effects of nanosecond pulsed laser irradiation on oxidised steel surfaces were investigated, in order to estimate the possibility of using laser techniques for cleaning applications. During high temperature oxidation, the oxide layer developed on the surface of pure Fe consisted of two successive layers: a 20 nm-thick Fe/sub 2/O/sub 3/ and a 1000 nm-thick Fe/sub 3/O/sub 4/ ones. In the case of the stainless steel containing 18% Cr, the surface layer was consisted of Cr-oxide; whilst in the case of the steel containing 15% Cr and 6% Al, it consisted mainly of Al-oxide. Both oxide layers presented a sub-micron thickness For the purpose of this work, a Nd:YAG laser, emitting at 1064 and 532 nm, with a FWHM pulse of 145 ns, was used. The influence of the wavelength, the energy density, the number of pulses and the cathodic polarisation of the metallic sample, on the removal mechanisms and the cleaning efficiency of the technique was investigated.