Effects of tensile stress ratio and amplitude on tension-torsion fretting-corrosion-fatigue behaviors of non-perpendicularly crossed steel wires

Steel wires, non-perpendicularly crossed in the hoisting rope, are subjected to tension-torsion fretting-corrosion-fatigue during coal mine hoisting. The tensile stress ratio and amplitude greatly affects tension-torsion fretting-corrosion-fatigue behaviors of non-perpendicularly crossed steel wires. Hysteresis loops of tangential force versus displacement amplitude and torque versus torsion angle, and coefficient of friction were presented to explore dissipated energy and friction characteristics, respectively. Wear scar profiles were observed by scanning electron microscope and white light interferometer to discuss wear mechanisms. Crack propagation morphologies of steel wires were observed using X-ray computed tomography to obtain crack propagation rates. The fractal theory was innovatively introduced to quantitatively demonstrate surface complexities of wear scars. Meanwhile, by the innovative introduction of acceleration factor and establishment of tension-torsion fretting-corrosion-fatigue life estimation model, influence degrees of tensile stress ratio and amplitude on the crack propagation rate, tension-torsion fretting-corrosion-fatigue life and electrochemical corrosion rate were explored. X-ray photoelectron spectroscopy was employed to analyze element compositions and valence distributions of reaction products of wear scars. The electrochemical analyzer was used to investigate electrochemical polarization curves and impedance spectroscopy. The results show that increases of tensile stress ratio and amplitude cause overall increases in the dissipated energy, coefficient of friction, maximum wear depth, crack propagation rate, influence degree on the life, fractal dimension and surface complexity. Experimental results coincide well with results from estimation models. The electrochemical corrosion damage decreases with increasing stress ratio and with decreasing stress amplitude.