Improved temper roll-force prediction through microstructural modelling

The yield point phenomenon, which compromises the mechanical behaviour of steel sheets, can be removed by temper rolling. To achieve accurate rolling force predictions, this research develops a microstructural material model based on dislocation density and mobility. Novel experiments will be used to validate the numerical models. These will then be integrated into a semi-analytical framework for fast, online prediction of rolling force. Improved understanding of the yield point phenomenon will have a direct effect on reducing scrap rates.

The first goal is to improve the understanding on the yield point phenomenon. This will be achieved by a combination of novel testing and modelling approaches. Utilizing test methods that can isolate the material behaviour from that of the structure it is aimed that a direct observation, as compared to inference, of the phenomenon will improve the understanding of the physics of the process. A novel material model will be developed that takes a more physics-based approach to modelling of the phenomenon at the microstructural scale.

Figure 2. Surface shear band formation with increasing thickness reduction

The second goal is to utilize the developed material model in a full-scale FE simulation of the temper rolling process. This will serve as a benchmark model for prediction of the roll force.

Figure 3. FE simulation of the temper rolling process

The final goal is to improve the accuracy of the predictions of roll force that are currently obtained using a quasi-1D semi-analytical approach. By incorporating the improved material model into the slab method, it is foreseen that the predictions will yield more accurate results which will improve product and process quality.