Effect of chromium and boron additions on the warm rolling behavior of low carbon steels

Abstract

The warm rolling of steels within the ferrite region can be a cost effective method of producing certain sheet materials. However, In the presence of solute carbon atoms, the rate sensitivity of the material can be affected as a result of dynamic strain ageing (DSA). This can significantly influence the microstructural development during processing, particularly due to the suppression of shear band formation. Shear bands help promote the development of a strong {111} texture during annealing, the presence of which is necessary to ensure high r-values in the final product. Therefore, the warm rolling of low carbon (LC) steels usually results in products with poor formabilities. However, it is known that the DSA behavior can be modified by the addition of elements such as boron and chromium. Three experimental low carbon steels with various additions of Cr and B were warm rolled; their behaviors are compared to that of a standard LC material. It was found that these additions promote the formation of shear bands at somewhat higher rolling temperatures than in the unalloyed steel, thus potentially resulting in stronger {111} recrystallization textures. Therefore, additions of Cr and B could lead to the production of warm rolled LC steels with improved formabilities.