Catenary is an important part of high-speed railway system.Whether catenary can operate stably and reliably is related to the operation efficiency and safety of high-speed railway.The key parts of catenary are subjected to complex alternating loadings such as tension,compression,shear and torsion during service,and fretting corrosion occurs under the action of air pollutants,acid rain and marine atmosphere erosion,resulting in loosening and falling off of fasteners,or even fatigue fracture of parts.Therefore,it is very important to investigate the fretting corrosion behavior of key components of catenary.In this paper,the Al-Mg-Si alloy(6082 alloy),which is commonly used for manufacturing catenary parts,was selected as the research object.On the basis of fretting dynamics and corrosion electrochemical analysis,combined with tribological and electrochemical performance tests,as well as scanning electron microscopy(SEM),optical microscope,EDX analysis,X-ray photoelectron analysis,the effects of normal load,displacement amplitude,polarization and fretting frequency on fretting corrosion behavior of 6082 aluminum alloy in 3.5% NaCl solution were investigated by a highprecision fretting-corrosion apparatus(mfc-01).The major work and conclusions of this thesis are as follows:(1)The load and displacement amplitude had significant impact on the fretting state,and a running condition fretting map(RCFM)was established.The corrosion behavior of the material is closely related to the fretting condition.In slip regime,the corrosion was weakened by fretting,while in partial slip regime and mixed fretting regime,the corrosion was accelerated.(2)The wear mechanism,wastage and micro-abrasion-corrosion synergy maps concerning the displacement and applied load were generated to evaluate the frettingcorrosion behavior of the 6082 alloy.The wastage map showed that the material loss level was related to the fretting state: the mixing fretting regime and slip regime were basically of medium or high loss level,while partial slip regime was of low loss area.The wear mechanism map showed that the fretting-corrosion behavior of 6082 alloy was mainly dominated by micro-abrasion-corrosion and micro-abrasion.The synergy map showed that the "synergism" was the main interaction in the fretting corrosion process of 6082 alloy,that was,corrosion and wear promoted each other,and there was a negative interaction under some conditions(small load and large displacement,large load and small displacement).(3)Under the anodic potential polarization,the surface of the material was more prone to slip,so the range of gross slip zone was expanded,mixed zone and partial slip zone were narrowed.Under cathodic and self-corrosion potential polarization,the corrosion of the wear region was accelerated by the fretting behavior.While under the anodic polarization,the corrosion of the wear region was reduced by the fretting behavior.The damage degree of the material increased with the positive shift of the applied potential.Under cathodic and self-corrosion potential polarization,the wear mechanism of 6082 aluminum alloy was mainly delamination mechanism and slight abrasive wear,while under anodic potential polarization,that was mainly abrasive wear and corrosive wear.(4)When the displacement amplitude was large,the frequency had no obvious influence on the fretting state of the material,but when the displacement amplitude was smaller,the surface of the material was more likely to slip at low frequency.As frequency increased,the friction coefficient increased.The corrosion rate was accelerated with the increase of frequency.The loss volume decreased with the increase of frequency.When the frequency was low,the damage mechanism of materials was mainly abrasive wear,peeling and serious electrochemical corrosion,while when the frequency was high,the damage mechanism was mainly abrasive wear,fatigue caused by mechanical action and slight electrochemical corrosion. |