Cavitation erosion behaviors of surface chromizing layer on 316L stainless steel.

• Cavitation erosion behaviours of surface chromizing layer were investigated. • The pitting and galvanic corrosion resistances were enhanced due to high Cr concentration. • Excellent combination of surface hardness and surface toughness was obtained. • The cavitation erosion mechanism of chromizing layer was proposed. To enhance the cavitation erosion resistance of industrial components, two types of Cr-rich diffusion layers were fabricated on 316L stainless steel through pack chromizing process. The chromizing layer before post heat treatments exhibited poor cavitation erosion performances, which could be ascribed to its high brittleness and the galvanic corrosion. The chromizing layer after post heat treatments showed the excellent cavitation erosion resistance with a 3.97 times lower erosion mass loss compared with that of 316L stainless steel. The corrosion resistance was significantly improved with a 12.5-time lower free corrosion current density than 316L stainless steel, and the surface mechanical properties of chromizing layer also exhibited great combination of hardness and toughness. Therefore, the higher cavitation resistance was attributed to the better corrosion and mechanical performances originating from the more homogeneous microstructure after post heat treatments. [ABSTRACT FROM AUTHOR]