Laser surfacing of S31603 stainless steel with engineering ceramics for cavitation erosion resistance

As a preliminary study on incorporating ceramic particles into stainless steels for improving cavitation erosion resistance, ceramic-reinforced coatings were fabricated on austenitic stainless steel UNS S31603 using a laser surfacing technique. Ceramic powders, including WC, Cr3C2, SiC, TiC, CrB2 and Cr2O3, were used to produce surface metal matrix composites (MMCs) with high volume fractions of reinforcement. The powders were pasted on the surface of UNS S31603 first, followed by surface melting using a high power laser. The microstructures and structures of the surfaces were analyzed. The cavitation erosion characteristics of the surface-modified specimens in 3.5% NaC1 solution at 23°C were studied by means of a 20-kHz ultrasonic vibrator at a peak-to-peak amplitude of 30 μm. The cavitation erosion resistance Re of all the laser-modified specimens was improved, except for the case of Cr2O3, with the improvement depending on the microstructure formed. The Re of surface MMCs reinforced with CrB2, WC and TiC increased to 9.4, 8.5 and 1.7 times that of monolithic S31603, respectively. For the specimens modified with Cr3C2 and SiC, a eutectic mixture of austenite and carbides or silicide was formed and the Re was increased by a factor of 4.8 and 2, respectively.