Abstract: In a first step of the method of achieving TRIP microstructure in steels by deformation heat, steel feedstock is heated to a temperature below the temperature at which austenite begins to form in the steel in question, i.e. below AC1. In a next step, the feedstock is formed into a final product, using applied severe plastic deformation whereby deformation energy causes the temperature of the material to increase to the final temperature between AC1 and AC3, and whereupon the ferrite-pearlite microstructure transforms into austenite. In a third or last process step, the final product is cooled down from the final temperature to the temperature of the bainite nose of the material (B). The cooling is then interrupted and the material is held at the temperature of the bainite nose (B). Consequently, the TRIP microstructure forms. Finally, the product is cooled down to ambient temperature.

Abstract: According to the method of production of a steel sheet pressed part with locally modified properties, the steel sheet blank is first heated in a device for heating to the austenitic temperature of the material. Next, the steel sheet blank is converted in a tool for deep drawing by deformation into a final drawn part. Subsequently, the final drawn part is cooled inside the tool for deep drawing. Various locations of the final drawn part are cooled to various temperatures and/or at various rates during the cooling process. Thereafter, the final drawn part is placed in an annealing device, where retained austenite stabilization occurs by diffusion-based carbon partitioning within the material from which the drawn part is made. After stabilization, the final drawn part is removed from the annealing device and air cooled to ambient temperature.