Corrosion Fatigue Fracture Behavior of High-Strength Cu Trolley Wire for High-Speed Railroad Services
Komai Kenjiro; Minoshima Kohji; Miyazawa Kohji
Abstract:One of the limiting factors in an operation of a high speed train is the wave propagation rate in trolley wire, because the current collecting performance is reduced when the speed of a train reaches the wave propagation rate. Therefore, an operation of a high speed train requires trolley wire with high wave propagation rates. For this purpose, the trolley wire should be tightened up with high tension stress which in turn requires a high strength property and/or should have less density, although the mechanical properties including wear and (corrosion) fatigue and other properties such as electric properties should be sufficient. In this investigation, fatigue and corrosion fatigue properties have been evaluated in a newly developed high strength Cu Sn trolley wire for an operation of a high speed train. The influence of NaCl solution on corrosion fatigue life is found negligible, because of relief of stress concentration due to initiation of multiple cracks, blunting of corrosion fatigue crack tip by dissolution, and decrease in total crack depth due to general corrosion on the wire. Therefore, the corrosion fatigue strength is determined by mechanical fatigue strength in air. Attention is also paid to crack initiation and corrosion behavior by using scanning electron and atomic force microscopy, and the mechanisms of corrosion fatigue are discussed. Key Words:corrosion fatigue, fatigue strength, crack initiation, environmental strength, atomic force microscopy, trolley wire, high-speedtrain