WEB Influence of high temperature corrosion on thermomechanical fatigue behaviour of a roughing mill work roll alloyThursday (24.09.2020) 16:25 - 16:40 S: Structural Materials 1 Part of:
Due to the growth of high-strength steel production, rolls for hot rolling mills are facing higher mechanical loads and increasing contact temperatures. Therefore, continuous improvements of wear behaviour and process safety are required. Work rolls are in contact with the hot strip and therefore their surfaces are exposed to high alternating temperature and strain. In combination with water vapour, caused by roll cooling, this leads to accelerated high-temperature corrosion and thermomechanical fatigue of the material. In roughing mills, where several high deformation passes at highest temperatures are carried out, the impact of oxidation on the thermomechanical fatigue might be of particular importance.
The objective of the study presented is to improve the understanding of damage mechanisms and damage evolution in roughing mill rolling processes, especially the interaction between oxidation and thermomechanical fatigue. The oxidation behaviour of a roughing mill work roll alloy itself was investigated in a prior study by thermogravimetric analysis. By means of the finite element method (FEM) the periodic variation of temperature, stress and strain at the rolls surface was calculated for the present study. Based on the results obtained, isothermal and thermomechanical fatigue experiments were carried out on the work roll alloy. In order to understand the effect of oxidation processes on the fatigue damage, several vacuum thermomechanical fatigue experiments were also carried out. Furthermore, samples from worn out work rolls were taken and analysed, in order to compare real damage mechanisms with those occurring under laboratory conditions. The results of both, thermomechanical fatigue experiments and work roll damage analysis will be presented and discussed in this contribution.