Solid particle erosion, an important material degradation mechanism encountered in a number of technological and engineering systems, has been investigated intensively over the last few decades. The influence of erodent particle and particle flow related variables on the erosion behaviour is reasonably well understood. On the other hand, in spite of the availability of a large database, the effect of the properties of the eroding material on its erosion behaviour is yet to be fully clarified. Such a poor level of understanding can be primarily traced to the fact that erosion involves the deformation of the material under high strain rate, adiabatic and constrained conditions and to the fact that the properties of the material are not known under such unique deformation conditions. In this paper, the influence of the various conventional strengthening mechanisms on erosion resistance of metallic materials is first discussed. Next, the unique aspects of material deformation during erosion are highlighted and the plastic flow behaviour of metallic materials under such conditions is explored. Finally, an erosion model, incorporating the ideas brought out in the earlier sections, is presented and utilized to explain much of the available experimental data. © 1995.