Computer Modeling Of Thin Slab Continuous Rolling Deformation And Microstructure Evolution

Strip plays an important role in the development of domestic economy, and the products are widely used in industry, agriculture, national defence and civil areas. It can not only be used as slab and sheet, but also as raw and processed materials of cold rolling, weld tube, and cold banding beam. An integrated simulator has been developed for simulating rolling loads, temperature and microstructure variation during hot strip rolling process. For simulation the Orowan formula is used to calculate the stress and strain, and finite difference method is used to analyze the temperature variation of both work piece and roll. The simulator has been used for predicting the temperature, austenite grain size and phase transformation in an actual strip rolling process. In the course of calculating temperature field, the mathematical modeling takes into consideration of the plastic work, friction heat, heat convection, radiation, descaling, cooling between rolls and stream cooling. The advanced mathematical modeling of flow stress is based on Jihua Zhou and Kezhi Guan's equation, but incorporates the effects of dynamic, meta-dynamic, static recrystallization, and also takes dynamic recovery and the accumulated strain in account. Using principle of superposition, an austenite evolutive incremental mathematical model is adopted in simulating microstructure variation during the continuous rolling, and an incremental model of phase transformation is used in simulating continuous cooling after hot forming. A numerical program is compiled in the environment of Microsoft Developer Studio, simulating the manufacturing process of furnace outlet—descaling—rolling—stream cooling—coiler entry. The distribution and variety of thermal field, microstructural evolution along strip length and thickness at optional moment and position are founded. The simulator has been used for predicting the variation of temperature, austenite grain size and the phase transformation in an actual strip rolling process. The predicted values are in good agreement with measured ones.