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

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 fo und, as previously shown, that erosion rate is dependent on velocity by a p ower law, given by ER = kV(n). However, the velocity exponent ii was found to be target material independent and is governed by test conditions, inclu ding particle characteristics and the erosion test apparatus. In addition, n is not dependent on the erosion mechanism. Results from tested as-quenche d martensite and tempered martensite showed that the exponent is approximat ely 2.9 for both materials, even though martensite eroded by a brittle crac king mechanism, while tempered martensite eroded by a plastic deformation m echanism. 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, indica ting 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 r esults generated at different times are to be compared. (1) (C) 1999 Publis hed by Elsevier Science S.A. All rights reserved.