Effect of Load Ratio on Fatigue Failure Micromechanisms of Railway Axle Steel

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The paper presents the basic regularities of fatigue failure of the railway wheelset axle material – OsL steel (C - 0,40—0,48 %; Mn - 0,55—0,85 %; Si - 0,15—0,35 %; P < 0,04%; S < 0,045 %; Cr < 0,3 %; Ni < 0,3 %; Cu < 0,25 %). It was revealed that under loading stress ratio R = 0, fatigue crack growth is 2 ... 4 times lower than that at the asymmetry R = -1. In doing so, amplitude of stress intensity factor vary in the range of 20 – 35 MPa√m. The micromechanisms of fatigue crack growth are described and systematized, while physical-mechanical interpretations of the relief morphology at different stages of its growth are offered.