微动频率对钢丝拉扭复合微动腐蚀疲劳行为影响研究

拉扭复合微动腐蚀疲劳是深井提升钢丝绳主要失效形式之一，深井提升钢丝绳振动频率决定钢丝间微动频率，直接影响钢丝拉扭复合微动腐蚀疲劳机理和损伤程度，进而制约深井提升钢丝绳服役安全性. 本文作者通过自制钢丝拉扭复合微动腐蚀疲劳试验机开展了酸性电解质溶液中钢丝拉扭复合微动腐蚀疲劳试验，通过钢丝切向力-位移幅值和扭矩-扭转角滞后回线分析了拉扭复合微动腐蚀疲劳过程中钢丝间接触状态及轴向和扭转方向钢丝耗散能，运用扫描电子显微镜和三维白光干涉表面形貌仪考察了拉扭复合微动腐蚀疲劳过程中钢丝磨痕形貌和磨损深度轮廓特性，采用X射线三维成像系统揭示了钢丝拉扭复合微动腐蚀疲劳裂纹扩展演化规律，通过电化学分析仪分析试验后钢丝Tafel极化曲线和阻抗谱以探究钢丝电化学腐蚀倾向和耐腐蚀性，揭示了微动频率对拉扭复合微动腐蚀疲劳过程中钢丝间接触状态、钢丝耗散能、微动磨损机理、疲劳裂纹扩展演化和疲劳寿命、电化学腐蚀倾向和耐腐蚀性的影响规律. 结果表明:在拉扭复合微动腐蚀疲劳过程中，随着微动频率的增加，钢丝间由完全滑移和部分滑移混合状态变为完全滑移状态，钢丝扭矩-扭转角滞后现象削弱，钢丝切向力-位移幅值和扭矩-扭转角滞后回线对应的耗散能均总体降低，钢丝间摩擦系数和钢丝磨损深度均降低，钢丝磨损机理均为磨粒磨损、黏着磨损、疲劳磨损和腐蚀磨损，钢丝最大裂纹深度和裂纹扩展速率均降低，疲劳寿命增加，钢丝电化学腐蚀倾向下降和耐腐蚀性增强. 

Effect of Fretting Frequency on Tension-Torsion Fretting Corrosion Fatigue Behavior of Steel Wire

Tension-torsion fretting corrosion fatigue is one of main failure modes of hoisting rope in the deep coal mine. The vibration frequency of hoisting rope in the deep coal mine determines the fretting frequency between steel wires, directly affects the tension-torsion fretting corrosion fatigue mechanism and damage degree of steel wire, and thereby restricts the service safety of hoisting rope in the deep coal mine. In the present study, the self-made tension-torsion fretting corrosion fatigue testing rig was employed to conduct tension-torsion fretting corrosion fatigue tests of steel wires in the acid electrolyte solution. Hysteresis loops of tangential force versus displacement amplitude and torque versus torsion angle of steel wires were established to analyze the contact status between steel wires and dissipated energies along axial and torsional directions during tension-torsion fretting corrosion fatigue. The scanning electron microscope and three-dimensional white-light interferometer for surface topography were employed to investigate wear scar morphologies and evolution characteristics of wear depth profile of steel wires during tension-torsion fretting corrosion fatigue. The X-ray three-dimensional imaging system was employed to reveal tension-torsion fretting corrosion fatigue crack propagation evolution laws of steel wires. The Tafel polarization curves and impedance spectra of steel wires after tension-torsion fretting corrosion fatigue tests were analyzed by the electrochemical analyzer in order to explore the electrochemical corrosion tendency and corrosion resistance of steel wires. Meanwhile, the influence laws of fretting frequency on contact statuses between steel wires, dissipation energies of steel wire along axial and torsional directions, fretting wear mechanisms of steel wire, fatigue crack propagation evolutions and fatigue lives of steel wires, electrochemical corrosion tendency and corrosion resistance characteristics of steel wires were revealed. The results showed that the contact status between steel wires varied from the mixed states of gross slip and partial slip to the gross slip state during tension-torsion fretting corrosion fatigue with increasing fretting frequency. The hysteresis phenomenon of torque versus torsion angle of steel wire weakened with increasing frequency. An increase of frequency causes overall decreased in dissipation energies corresponding to hysteresis loops of tangential force versus displacement amplitude and torque versus torsion angle of steel wire. The coefficient of friction between steel wires and the wear depth of steel wire both decreased with increasing fretting frequency. Wear mechanisms of steel wires were abrasive wear, adhesive wear, fatigue wear and corrosion wear in cases of all frequencies. An increase of fretting frequency causes decreased in the maximum crack depth and crack propagation rate of steel wire and an increase in the fatigue life of steel wire. The electrochemical corrosion tendency of steel wire decreased and the corrosion resistance of steel wire increased with increasing fretting frequency.