Study On Fatigue Property And Strength Improve Method Of Cu-Ni-Si Alloy Used In Steady Clamp Of High Speed Railway Catenary

With the continuous increase of operation times of China's high-speed railway,accidents caused by failures of the catenary steady clamps often occur,and these induce seriously affects on operational safety of high-speed rails.During service,steady clamps suffer from corrosion environment such as acid rain and industrial exhaust gases,as well as fatigue loads caused by pantograph operating,winds,etc.,which result in fatigue failure and corrosion fatigue failure of the steady clamp.In this paper,CuNi₂Si,which is the manufacturing material of the steady clamp,was used to perform tensile test and fatigue tests.The effects of pre-cooling deformation,surface particle shot peening,and corrosive environment on fatigue performance and failure behavior were studied.And based on the fatigue performance data of CuNi₂Si under various processing conditions,the fatigue life simulation of the steady clamp is performed.The results show:?1?The pre-cold worked treatment significantly increases the yield strength,tensile strength and hardness of CuNi₂Si,but decrease elongation,reduction of area,and fatigue strength.After the crack initiation in the specimen with the cold working,they propagate along the direction,which in to the 45°loading direction until the fracture.?2?Micro-shot peening increased the corresponding fatigue strength of CuNi₂Si alloy 10⁷cycle life by 50%,and the CuNi₂Si S-N curve exhibits a step-wise shape?The fatigue crack initiate from the surface at high stress level,and fatigue crack initiate from the subsurface at low stress level.?3?Under the 5%NaCl atomization environment,the fatigue strength of the non-surface treated specimens 10⁷ cycle life decreased by 60%,and the fatigue strength of the micro-shot peening specimens 10⁷ cycle life decreased by 25%.The results showed that the micro-shot peening was obvious improve the corrosion resistance of CuNi₂Si alloy.Corrosion fatigue fracture presents intergranular brittle fracture.?4?The fatigue simulation results of the steady clamp based on the CuNi₂Si fatigue performance data under various conditions indicate that the simulated fatigue life of specimens which under the cold working and the corrosive environment meet the requirements of the railway industry standards,the simulation results show that the fatigue risk points are located the inner side threaded hole of the ring clamp of steady clamp.