Abstract
	High strength steels with good formability are used for weight reduction in automobile industry especially. TRIP steels are one of these groups of high strength steels. It can be achieved excellent combination of mechanical properties – high strength (to 1200 MPa) and eminent formability (ductility to 35%) by treatment of steels with TRIP (Transformation Iinduced Plasticity) effect utilisation. Fundamental of this feature is stabilisation of substantial amount of retained austenite down to the ambient temperature at thermomechanical processing and its subsequent transformation for strain induced martensite in consequence of applied plastic deformation. Stability of retained austenite against SIMT (Strain Induced Martensitic Transformation) is main factor affecting plastic properties of material. Microstructure of TRIP steels made up by multiphase structure of polygonal ferrite, pearlite, bainite, acicular ferrite and certain amount of retained austenite. TRIP steel thermomechanical processing simulation concepts and subsequent microstructure evaluation concepts are presented in this paper. The aim of the work is to specify single thermomechanical processing parameters influence on TRIP steel microstructure. The thermomechanical hot rolling condition of TRIP steel will be optimized in terms of mentioned results. TRIP steel thermomechanical processing was simulated by way of step shape samples and flat samples laboratory thermomechanical rolling. Rolling were performed on step shape samples for exact trend determination of single relations whereas plain samples were thermomechanically rolled to define mechanical properties particular values. Utilization of different etching methods, light optical microscopy and electron microscopy including EBSD and even X-ray diffraction were verified within final microstructure metallography evaluation.