Research On The Erosion (Cavitation) Behavior Of Copper Alloys Under Multiphase Flow

Copper alloys, with good biological-corrosion resistance, have been widely used inthe ship for its poisonousness achieved from the dissolved copper ions.Service environment of ship propeller is a complex multiphase flow system whichincludes solid, liquid and gas phase. The interaction of cavitation and erosion is the mainreason for the failure of propeller. At present, the studies of interaction under multiphaseflow focus on stainless steel, low alloy steel and high manganese steel. It is rarely reportedon the cavitation and erosion cooperative behavior of copper alloy.In this paper, tin brass and aluminum bronze were selected, which were widely usedas ship propeller. The mechanism of erosion-cavitation and erosion behavior about copperalloys has been discussed in the simulated actual service environment of propeller. Andmeanwhile the influencing factors and rule have been also investigated. The results are asfollows:(1) The failure of copper alloys results from the cooperative cavitation and erosion.Compared to the effect of cavitation, the damage effect of erosion is greater during thecooperative interaction of cavitation and erosion. The weight loss of copper alloys causedby cavitation and erosion increases with increasing sediment concentration.(2) For tin brass, massive shedding under cavitation condition and long furrowsunder erosion condition is shown, respectively. After cavitation and erosion,non-directional short furrows and scaly pits are shown on the surface of tin brass,meanwhile, the significant work hardening phenomenon and cracks which start from theα/β phase boundaries appears.(3) In erosion process, the impact force is divided into the vertical component andthe horizontal component related to the sample surface, irrespectively. Horizontalcomponent led to mass loss or the generation of protuberant lip. Under the vertical force，the forged and extruded protuberant lip fall off from the surface. Cutting wear processplays a major role in erosion damage of copper alloys.(4) The weight loss of two kinds of copper alloys increases linearly with increasingerosion time, which is lower for aluminum bronze compared to that of tin brass. Thedirection of long furrow is consistent with the direction of water flow on the erosionsurface. The mechanical cutting action plays the key role in erosion failure in the corrosionenvironment，and corrosion and erosion promote each other. (5) The weight loss of two kinds of copper alloys increases with the increase oferosion speed and sand particle size. When the impact angle is lower than30°, the erosionfailure is enhanced with increasing angle, which mainly results from wear. The weight lossof erosion is maximum while the erosion angle is30°. The weight loss decreases when theimpact angle is higher than30°, which is dominated by local plastic deformation.