Cavitation erosion and damage mechanisms of alloys with duplex structures

The cavitation erosion characteristics of alloys with duplex structures such as super duplex stainless steel (UNS S32760) and α+β brass (Cu–40%Zn) in 3.5% NaCl solution at 23°C were investigated by means of a 20 kHz ultrasonic vibrator at a peak-to-peak amplitude of 50 μm. Austenitic stainless steel (UNS S30400) with single phase structure was also investigated for comparison purpose. The effect of heat treatment on the cavitation erosion characteristics of these alloys was also studied. Heat treatment of brass and S30400 stainless steel increases the grain size and ductility, and decreases the mechanical strength of these alloys, leading to an increase of erosion loss. For S32760, the effect of heat treatment on the mechanical properties and grain size is minimal and therefore erosion loss is unaffected. Hardness, tensile strength, engineering strain energy and grain size of the heat-treated alloys correlate well with the cavitation erosion resistance Re by linear regression.