Influence of hot-working conditions on a structure of X11MnSiAl17-1-3 steel for automotive industry

The investigations are focused on high-manganese austenitic steel used for reinforcing elements of a car body. The main purpose of this paper is to determine the effect of various conditions of thermomechanical treatment carried out on Gleeble 3800 simulator being on equipping Scientific and Didactic Laboratory of Nanotechnology and Materials Technologies, Institute of Engineering Materials and Biomaterials, Silesian University of Technology in Gliwice Poland, and LPS module for semi-industrial hot-rolling on the structure and phase transformations occurring during cold plastic deformations. Thermomechanical treatment consists of a four passovers with a planned true strain equal 4 × 0.23. There were three variants of cooling after thermomechanical treatment: cooling in water, natural air-cooling and cooling in water after isothermal holding for 30 s at the temperature of last deformation 850°C. After thermomechanical treatment of high-manganese austenitic steel performed in the laboratory Gleeble 3800 simulator and industrial conditions of LPS module can be concluded that simulation in laboratory conditions allows to obtain fine-grained austenitic structure. Rolling performed in the semi-industrial conditions in the LPS rolling mill did not allow to achieve the assumed parameters of thermomechanical treatment, such as temperature and planned strain during successive deformations. These factors have led to the lack of a uniform structure fragmentation of the rolled material, and also have an influence on mechanical properties obtained during cold plastic deformation.