THE DEPTH OF PLASTIC-DEFORMATION BENEATH ERODED SURFACES - THE INFLUENCE OF IMPACT ANGLE AND VELOCITY, PARTICLE-SHAPE AND MATERIAL PROPERTIES

The solid particle erosion behaviour of a variety of metals and alloys has been characterized over the past years. However, very little attention has been paid to the nature and size of the plastic zone that exists just beneath the eroded surface. This is indeed surprising since the size of the plastic zone is the primary parameter which determines the magnitude of the energy dissipated via plastic deformation. Thus, if the erosion rate is deformation controlled (i.e. the fracture event is easy and not rate controlling), a definite correlation should exist between the size of the plastic zone and the erosion rate. In fact the localization model for erosion, proposed earlier by the present author, predicts the erosion rate to be proportional to L3 where L is the plastic zone size. The main objective of this paper is to investigate the influence of test and material variables on the extent of the plastic zone that exists beneath the eroded surfaces. Towards this purpose the experimental data on the plastic zone size beneath eroded surfaces in a variety of metallic materials such as 304, 316 and 410 stainless steels and copper and its alloys eroded over a range of velocities and impact angles are presented. The experimental data illustrating the influence of particle shape (angular vs. spherical) and the erosion test temperature on the plastic zone size are also provided. All of the above experimental data regarding plastic zone size are rationalized on the basis of a theoretical model. Finally, the correlation that exists between the plastic zone size and the erosion rate is also emphasized.