AbstractAlthough much research has been carried out on the erosion of materials in aqueous slurries, little attention has been given to defining transitions between erosion regimes in such environments. This is despite the large amount of work that has been carried out in this area in‘dry’high temperature corrosion environments. Defining transitions between regimes permits distinction between erosion and corrosion dominated behaviour, which can be an aid to materials selection and to process monitoring in such conditions. This paper describes the basis of a relatively simple theoretical method for evaluating the transitions between erosion and aqueous corrosion regimes. Models for solid particle erosion at normal impact are combined with those for aqueous corrosion to define regimes of damage in corrosion conditions varying from dissolution to passivation. This permits the construction of the erosion–aqueous corrosion map where the transitions between the regimes are shown as a function of erosion and aqueous corrosion variables. The rationale for the regimes suggested is discussed on the basis of research on erosion maps in oxidising conditions. The boundaries on the maps are compared with experimental data. Other issues addressed in this study include using the erosion–corrosion map to identify favourable and adverse operating conditions in addition to identifying the mechanism of damage.MST/3543