Microstructural Evolution and Mechanical Properties of Friction Stir Processed TRIP780 Steel
Imren OZTURK YILMAZ Mümün YILMAZ Onur SARAY
AbstractFriction stir processing (FSP) is a method which refines microstructure of metals by localized plastic deformation. This microstructural evaluation brought a remarkable increase in mechanical properties with an acceptable loss of ductility. In the literature there are several publications on the microstructural and mechanical evolution of FSPed steels. However, there limited number of studies on the effect of FSP on the microstructure and mechanical properties of Transformation-Induced Plasticity (TRIP) steel as a widely used material with unique properties like excellent formability and strain hardenability. In order to close this gap, current study is mainly concentrated on the effect of FSP on the microstructural evolution and mechanical properties TRIP 780 steel. The microstructural evaluation was analysed scanning electron microscopy (SEM) techniques. Mechanical properties were investigated by microhardness test and tensile test. Results indicated that a two-fold increase in the hardness was achieved after FSP. Also, yield strength and UTS of the TRIP-780 steel reached to 1280 MPa and 1475 MPa respectively. This strength increase was also obtained with an acceptable uniform elongation of % 9, which is concluded that a good balance of strength, ductility and strain hardenability.