Abstract
	The mechanical properties are explained in terms of the pore size and morphology, as well as the heterogeneous microstructures typical of ferrous powder metallurgy materials. The microstructures of sintered steels have been specific characteristics, which resulting from the base of powder metallurgy. The processing technology of sintered steels cannot avoid typical microstructural discontinuities such as pores and their agglomerates.  Especially, in term of effect on fatigue resistance, the pore is important, because microplastical deformation and represent the potential sites of the first microcracks forming. Nowadays, the material and technical potential of ferrous powder metallurgy enables the production of strength sintered steel parts for a wide spectrum of consumers. In term of assortment composition growths contribution the production of net-shape sintered parts and the production of sintered parts with a suitable modification of functional surfaces. In the praxis is the shot peening method frequently utilization. The fatigue behavior in terms of stress versus cycles (S-N curves) was almost identical for the two systems of prealloyed sintered steel Fe - Cr - Mo with addition of C. The specimens were pressed and sintered. The optimal choice of suitable construction material for particular component, construction requires the complex knowledge of fatigue resistance. Sintered specimens were tested in static tensile test on a ZWICK 1387 machine at an extension rate of 0.1 mm/min. Fatigue tests were carried out in symmetric plane bending at R=-1 using SCHENCK PWON testing apparatus. The maximum cycle number was 107. The surface modifications were carried out on KP-1 fa. G. Fischer laboratory testing apparatus. The aim of this work is to determine the effect of surface modification on the fatigue failure resistance. The value of fatigue limit for the pressed and sintered system of 190 MPa and for shot peened system of 260 MPa.