The process of descaling is a necessary part of forming processes, in which the clean surface before the contact with the tool is required. Hydraulic or mechanical methods are the most commonly used methods for descaling. Hydraulic high-pressure descaling is currently the most exploited process. Scales can be very diverse in terms of chemical bonds and mechanical properties. In principle, they can be divided into primary that are formed in specific conditions in the furnace, and secondary, arising in air. This article is focused on simulation of the hydraulic descaling of the layers of the secondary scale. To simulate the high-pressure spray, numerical analysis by Ansys was chosen, through which the influence of thermal and mechanical stress effects on the layer scale was classified. Numerical simulation of high-pressure spray was carried out in two steps. The first step was the simulation from the macro point of view, when the high-pressure spraying was simulated as a continuous function of heat transfer. This function has been experimentally measured in the test of the descaling nozzles. The second step was the simulation from the micro perspective. Very short but intense pulse of heat transfer on small areas was simulated. This approach represents a high-speed impact of a single drop of water. By studying these two aspects, it is possible to compare the impact of individual components, mechanical and thermal, on the stress in the layer scale. Such comparison reveals which of these components has a greater influence on the process and it is possible to design a strategy for hydraulic removal of scale to ensure process efficiency and quality of the surface.
