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 mel ting using 2 kW continuous wave Nd-YAG laser. The cavitation erosion a nd corrosion characteristics of laser surface melted stainless steels in 3.5% NaCl solution at 23 degrees C were studied by means of a 20 kH z ultrasonic vibrator at a peak-to-peak amplitude of 30 mm and a poten tiostat respectively. In a series of 4 h cavitation tests, the cavitat ion erosion resistance of laser-melted S31603 with 50% overlapping of melted tracks was found to be improved by 22% at 23 degrees C as compa red with the as-received specimen and very close to that of the as-rec eived S30400. No improvement on the cavitation erosion resistance of S 30400 and S32760 was found. The pitting potential of laser-melted S316 03 increased from 359 to 452 mV at 23 degrees C. The deformation mecha nism by cavitation and the pitting morphology of the laser-melted stai nless steels were discussed in terms of microstructure and residual st ress. (C) 1998 Elsevier Science S.A.