Speaker
Description
Previously, some of the problems of cracking as well as edge cracking during two phase thermomechanical hot rolling (e.g. duplex stainless, high Mn steels) have been attributed to the effect of hot ductility, difference of flow behaviour between the different phases. There is limited work and knowledge regarding the exact cracking mechanism as a function of rolling pass number, temperature, mean flow stress or reduction percentages. Using a high-speed camera during the rolling process, it is possible to address this and extract valuable information for optimizing the rolling process for such steels.
In a lab environment, a high-speed camera setup was used while rolling high manganese and aluminium steel concepts (Fe-Mn-Al-C alloys). Data such as crack initiation, crack propagation with each rolling pass were obtained for various rolling schemes, considering different reduction ratios, started rolling temperatures etc. Information from such experimental schemes was analysed based on alloying composition and thermodynamic equilibrium diagrams in the rolling temperature regions. Process maps were created incorporating data from the high-speed camera and phase equilibrium information. Insights from such studies were used to avoid edge cracking in some alloy compositions by adjusting the thermomechanical processing parameters during rolling. Such studies can be used to further optimize processing of such alloys or variation in alloying elements to avoid such dual phase regimes which are prone to hot ductility.