Erosion-corrosion Degradation of Additively Manufactured Metals

Metals and alloys produced by additive manufacturing (AM) are becoming more widely utilized across a number of industrial applications such as energy generation, flow machinery and aerospace. Questions remain, however, with regards to their degradation resistance when compared to conventionally manufactured equivalents. One form of material degradation that has yet to receive wider attention is erosion-corrosion of AM metals, a degradation mechanism that occurs in particle-laden corrosive fluids. The erosion-corrosion degradation of AM metals and their conventionally manufactured counterparts has been investigated in this study by using both experimental and computational methodologies. The degradation of AM nickel alloy 625 (UNS N06625) was compared with a conventionally manufactured equivalent within a submerged impingement jet (SIJ) at flow velocities of 10 m/s and 20 m/s, in ambient aqueous conditions containing sodium chloride and sand particles. To characterize the behavior of the fluid and the sand particles in the SIJ, a computational fluid dynamics model was developed to predict particle impingement angles and velocities at the test coupon surface. In combination with experimental results and surface analysis of the resulting wear scar, wear maps were constructed to compare the operational window for AM and conventionally manufactured equivalents in erosion-corrosion conditions. AM nickel alloy 625 generally experienced greater erosion-corrosion degradation rates at lower impingement angles compared to the conventionally manufactured equivalent but was also found to work-harden to a greater extent at high impingement angles.