Cavitation erosion and pitting corrosion of laser surface melted stainless steels

Surface modification of austenitic stainless steels S31603, S30400 and super duplex stainless steel S32760 was achieved by laser surface melting using 2 kW continuous wave Nd-YAG laser. The cavitation erosion and corrosion characteristics of laser surface melted stainless steels in 3.5% NaCl solution at 23 degrees C were studied by means of a 20 kHz ultrasonic vibrator at a peak-to-peak amplitude of 30 mm and a potentiostat respectively. In a series of 4 h cavitation tests, the cavitation erosion resistance of laser-melted S31603 with 50% overlapping of melted tracks was found to be improved by 22% at 23 degrees C as compared with the as-received specimen and very close to that of the as-received S30400. No improvement on the cavitation erosion resistance of S30400 and S32760 was found. The pitting potential of laser-melted S31603 increased from 359 to 452 mV at 23 degrees C. The deformation mechanism by cavitation and the pitting morphology of the laser-melted stainless steels were discussed in terms of microstructure and residual stress. (C) 1998 Elsevier Science S.A.