Modeling Solid-Particle Erosion of Ductile Alloys

properties for erosion protection. Hardness is the most SOLID-particle erosion is a loss of material during repetwidely used property to correlate with the erosion rates of itive impacts of solid particles and is one of the primary materials. For pure metals, some correlation between erosion reasons for fly ash–borne damage of power generation comrate and hardness has been shown.[4] However, several other ponents. A description of the erosion mechanism in terms of observations have shown that the erosion rate is not depenthe mechanical properties was presented by Bitter.[1] During dent on material hardness.[5,6] Hutchings[7] proposed that the impact, when the yield strength of the material is locally effect of hardness on erosion resistance is strongly dependent exceeded, plastic deformation takes place in the vicinity of on the properties of the erosive particles and erosion test the impact. After multiple impacts, a plastically deformed conditions (velocity, shape, size, and density of the particles). surface layer may form near the eroded surface, and, thereWhen hard angular particles strike a relatively soft target, fore, the yield strength of the material increases due to strain the target surface will deform plastically. On the other hand, hardening. Upon further deformation, the yield strength at when soft erodent particles are used, they may fracture upon the surface of the material will eventually become equal to impact. In this case, erosion damage will decrease as the its fracture strength, and no further plastic deformation will target hardness increases. In addition, the effect of hardness occur. At this point, the material surface becomes brittle and on erosion resistance depends on the velocity of the erosive its fragments may be removed by the subsequent impacts. particles. For example, it was established that the critical Some researchers have suggested that, during erosion, mateparticle velocity below which plastic deformation of the rial loss from a metal surface occurs when a critical fracture target does not occur is proportional to the target hardness.[8] strain is achieved at the surface.[2] A critical fracture strain This relationship is given by may be achieved locally after single or multiple impacts by