One of the major problems and challenges in forging of steels, is the formation of oxide scales during heating in the furnace and directly in the forging process. If it would be possible to predict the formation and the influence of the oxide scales under specific process conditions, negative influences on the forging process can be identified and prevented.
The aim of this work is the material characterisation of scale layer formation on various unalloyed and low-alloyed steels (C- and Cr-Steels) and the transfer of the identified properties into a FE-model for forging processes.
To achieve this goal, the selected steels are scaled at temperatures between 900 and 1200 °C each for 20, 40 and 120 s. The resulting scale layers are characterised using light microscopy analysis and EDXS. The focus will be on the growth, composition and porosity of the scale layers. In addition, the mechanical (flow curves and friction values) and thermophysical (thermal expansion, heat capacity and thermal conductivity) properties of the scale layers and their base material will also be determined.
The experimental data are the basis for the forging model. In this model, the scale growth under furnace atmosphere and the forging process will be calculated in a two-step simulation. First the oxide scale growth depending on the alloy concept and heating conditions and second the forging process considering the resulting scale layer from the first step. By applying the element-birth-death method, the scale layer is supposed to grow accordingly to the prevailing process parameters and the scales are not predefines as a homogeneous layer. As a result, the scale formation as well as the properties of the scales can be modelled under different process conditions. This leads to the development of a reliable model to predict the influence and the behaviour of oxide scales during forging processes.