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On the origin of hot rolling textures of ferritic stainless steels

University of British Columbia

The mechanisms leading to the alpha fibre texture development in hot rolled ferritic stainless steels are investigated. This texture, and particularly its rotated cube {001}<110> component, needs to be avoided to improve the mechanical properties of commercial alloys. The industrial hot rolling process is decomposed into carefully designed experiments that aim to study the contributions of plastic deformation and static recrystallization on texture development. On the one hand, it is shown that rolling of pancaked grain microstructures needs to be avoided as it strengthens the deleterious rotated cube {001}<110> component. The experimental observations are supported by crystal plasticity simulations. On the other hand, it is shown that the alpha plus cube fibre textures obtained after static recrystallization of hot rolled products (i.e. rolled >=900°C) differ fundamentally from the more classic gamma fibre texture in recrystallized warm and cold rolled products. The origin of this difference is attributed to the activation of different mechanisms of nucleation of recrystallized grains (bulging vs. intragranular) as a function of the specific deformation microstructures developed for each rolling condition. Under the assumption that nucleation occurs by abnormal subgrain growth, a model was developed to predict, using the characteristics obtained from a deformed microstructure, the static recrystallization texture. The experiments and model show that while static recrystallization of hot rolled products develop deleterious orientations, it also helps to maintain a weak texture. It is thus concluded that the alpha fibre texture cannot be avoided during the hot rolling process but that frequent recrystallization of the material during the interpasses of rolling can help to reduce its strength.

Text

2019-09-11

Attribution-NonCommercial-NoDerivatives 4.0 International

http://hdl.handle.net/2429/71664

Materials Engineering

University of British Columbia

UBCV

http://creativecommons.org/licenses/by-nc-nd/4.0/