Christian Doppler Laboratory

          Early Stages of Precipitation

Christian Doppler Laboratory

          Early Stages of Precipitation

 

 

Project manager: Matthias Nöhrer

 

As a consequence of the increasing requirements on steels in the automotive industry and also in pipeline applications, it is necessary to improve the mechanical properties of this kind of steel. An easy way to improve the performance of low and medium carbon steels is to add micro alloying elements, like Nb, V and Ti. These influence the austenitic grain size, grain size distribution and recrystallization behaviour. They also form carbides and nitrides, which increase the strength of the steel. The precipitation process can be supported by deformation, as during deformation the dislocation density increases which act as nucleation sides for the precipitates. The precipitations which are developing by that way are called strain induced precipitations.  However, the effect of the micro alloying elements can be controlled by heat treatment, rolling and cooling after rolling.
Micro alloyed steel has been investigated for many years. The early stage of precipitation forming and the precipitation potential after deformation is in literature less discussed. In the present work 0,2wt% carbon steels micro alloyed with Nb,Ti,V, Nb-Ti-V are under examination. The focus is laid on the precipitate behaviour after deformation, in the austenite region and in the austenite-ferrite region.