Microstuctural Changes and Corrosion Resistance of the Duplex Stainless Steels after the Laser Surface Processing

M. PICHIPIL, A. NASCIMENTO, M. PINTO, F. AUDEBERT Y M.C. LERARDI

Rio de Janeiro, Brasil

Workshop; III Workshop on Metastable and Nanostructured Materials” (NANOMAT 2006); 2006

The Duplex Stainless Steels are becoming very popular in different industrial applications because of their good mechanical properties and corrosion behaviour.  However in some aggressive environment it is require to enhance their corrosion behaviour. The application of laser surface modification to prolong the service life of engineering components exposed to aggressive environments has gained increasing acceptance in recent years. In the present work the surfaces of three duplex stainless steel were treated by Laser Surface Melting using a CO2 Laser with 400W and two different beam scanning rates. Microstructure characterization was carried out by means of X-ray diffraction and scanning electron microscopy.  The dynamic polarisation curves in 1M-NaCl at 50°C were obtained in order to discuss the laser surface melting effect on duplex stainless steels. In some cases a refinement of the microstructure and homogenisation of chemical composition were obtained. The corrosion resistance of laser surface-melted duplex stainless steels was found to be dependent on the microstructural change which was related to processing conditions.