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It is known that nominally brittle materials may exhibit plastic deformation in indentation, scratching, and microcutting when the loaded region is sufficiently small. The present investigation is concerned with the erosive cutting of nominally brittle materials by the impact of a stream of solid particles and it is shown that ductile behavior should be observed when the particle size and velocity are within certain limits. Experiments on a number of nominally brittle materials confirm this prediction; the ductile behavior being inferred from both the rippled appearance of the eroded surface and the variation of volume removal with angle of impingement.

An analysis is presented for the erosive cutting of a brittle material by the normal impact of a stream of solid particles. The volume of material removed by a given number of particles is predicted to be: W=krf1(m)Uf2(m) In this expression, k is a quantity involving material constants, r is the average radius, and U the velocity of the impacting particles. The exponents f1(m) and f2(m) are prescribed functions of m, the flaw parameter of the Weibull fracture strength distribution. Tests on a variety of brittle materials, using both angular silicon carbide particles and spherical steel shot, show the predictions of the analysis to be applicable over a wide range of particle sizes and velocities.

A discussion is presented on the behavior of materials during erosion. A rigorous analysis must make an assumption as to the mechanism of material removal, i.e., either ductile or brittle. One expects then, when comparing experimental results, that considerable differences in erosion characteristics will be apparent between these two classes of materials. In this paper it is shown that these differences do exist; however, for certain brittle materials, a considerable similarity to ductile materials exists. This similarity is in the dependence of erosion on abrasive particle velocity and diameter and on the material properties of the eroded surface.

A numerical model for particle-laden flow in a tube has been developed which predicts the erosive wear of the tube wall by the action of the impinging particles. Empirical relationships are used to correlate the particles’ momentum before and after impact with material properties. Erosion of a straight duct conveying a particle-laden stream was studied as experimental verification of the model. Specifically, an aluminum tube was eroded by much harder spherical particles and the resulting wear pattern compared with that predicted by the model. A close correlation was found. This is a first step in modeling more complex erosion effects in equipment in which two- and three-dimensional flows predominate.

Erosion of a material from a metal surface by the action of impinging SiC particles is studied. In a brief review, it is shown that investigators have correlated erosion wear with several material properties. These include fully annealed properties such as surface hardness, or properties relating to atomic band strength such as modulus of elasticity. In this paper, which studies the erosion wear for a number of pure ductile materials as well as alloys in the copper-nickel system, it is shown that a better correlation with erosion wear is achieved by using the Vickers hardness value of the fully work-hardened surface of the material. This quantity is probably the best material parameter to use in predictions of erosion resistance of metals and in the modelling of the erosion process.

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