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Influence of stress ratio R (R=σmin/σmax) on the fatigue crack path and fractographicfeatures of fatigue fractures of metal materials is investigated. As an investigated material were usedaluminium alloy АК6 (2,22 %Cu, 0.6 %Mn, 0,9 %Si, 0,6 %Mg, 0,3 %Zn, 0,7 %Fe, 0,1 %Ni) andaustenitic steel 110G13L (1,06 %C, 15,18 %Mn, 0,2 %Cr, 0,4 %Ni). Fatigue tests of prismaticsamples were conducted under the rigid scheme of loading under constant fatigue stress range(Δσ = const) in a wide range of ratio R.. The fracture surfaces of tested samples were investigated bymаcrо-, micrоfractographic methods and also X-ray diffraction analysis. It was shown the fatiguelife of samples and also quantity of loading cycles for crack propagation are stress ratio Rdependent. Maximum value of these parameters takes place under symmetric loading cycle at R=-1,and minimum value – at R→1. The generalized scheme of influence of ratio R on fatigue life ofsamples is presented. The increase of compressing stresses at the crack tip same influence, as well asincrease of stretching stresses on the fatigue life of samples, i.e. reduces both fatigue life of samplesand stage of crack propagation. A micro relief of a fatigue fracture and also degree of crystalstructure distortion of a material on the fracture surface are dictated by both micro mechanism of acrack propagation, and additional deformation from the compressing stresses, arising already afterthe fatigue crack passage.