The effect of velocity on the solid particle erosion rate of alloys

Abstract

Velocity is a critical test variable in erosion, and can easily overshadow changes in other variables, such as target material, impact angle, etc. The effect of velocity on erosion rate was studied in 70–30 brass (cold worked and annealed) and Fe–C martensite (as-quenched and tempered) and it was found, as previously shown, that erosion rate is dependent on velocity by a power law, given by ER= kV n . However, the velocity exponent n was found to be target material independent and is governed by test conditions, including particle characteristics and the erosion test apparatus. In addition, n is not dependent on the erosion mechanism. Results from tested as-quenched martensite and tempered martensite showed that the exponent is approximately 2.9 for both materials, even though martensite eroded by a brittle cracking mechanism, while tempered martensite eroded by a plastic deformation mechanism. No difference in the erosion rate relationship was found between the fully annealed and the 70% cold worked brass. The exponent n was found to change over time with nominally the same erosion test conditions, indicating that n is very sensitive to slight changes in erodent particles and/or the test apparatus, and that it must be measured periodically if erosion results generated at different times are to be compared. 1 Prime Novelty: The velocity exponent n is independent of both target material and erosion mechanism and is highly dependent on erosion test conditions for the materials tested. 1