暖湿气流对不同服役温度下轮轨界面黏着与损伤的响应行为研究

Response Behavior of Damp-Warm Air to Adhesion and Damage of Wheel-Rail Interface at Different Ambient Temperatures

为研究不同服役温度下高湿度暖湿气流对车轮材料黏着与损伤的影响,为列车轮轨的安全可靠服役提供理论参考.本文作者利用轮轨滚动接触磨损/疲劳试验机模拟宽温环境(-55~60℃)下,着重考察间歇暖湿气流对高速轮轨界面黏着与车轮表面损伤的响应行为.结果表明:同种暖湿气流(RH 99%)作用下,环境温度对轮轨滚动接触界面的黏着与损伤存在显著影响;在低温环境下,轮轨间的黏着系数会瞬时大幅度下跌,而高温环境下反而出现轻微上升的现象.在低温工况下暖湿气流诱导下的车轮损伤(如塑性变形和表面疲劳裂纹等)明显高于高温环境,磨损机制由低温环境下的疲劳磨损和磨粒磨损为主逐渐转变为高温环境下的氧化磨损、黏着磨损和疲劳磨损.因此,为进一步保障高寒地区列车通过隧道等湿热环境时的安全可靠运行,暖湿气流诱导列车轮轨低黏着状态的行为须予以关注和引起重视.

As an open and complex tribological system,the friction force(i.e.wheel-rail adhesion)and damage failure on the wheel-rail rolling contact interface are strongly interfered by the external environment,and the complex operating environment will seriously affect the service performance of the wheel-rail system.In order to study the effect of highhumidity warm and humid airflows on the adhesion and damage of wheel materials under different service temperatures,and provide theoretical reference for safe and reliable service of wheels and rails.In this paper,a wheel-rail rolling contact wear/fatigue testing machine was used to simulate the response behavior of intermittent warm and humid airflows to high-speed wheel-rail interface adhesion and wheel surface damage in a wide temperature range(-55~60℃).The results indicated that,under the same conditions of warm and humid airflows(99%RH),the ambient temperature had a remarkable impact on the adhesion and damage of the wheel–rail rolling contact interfaces.Under the condition of low temperature,the adhesion coefficient between the wheel and rail decreased rapidly,by contrast,there was a slight increase in the high temperature environment.The wheel damages(such as plastic deformation and surface fatigue cracks)induced by warm and humid airflows under low temperature condition was significantly higher than that in high temperature condition.At low temperature,the material was brittle,the pits on the wear surface were significant,and the abrasive particles formed by fatigue spalling provided the possibility for the ploughing effect.In addition,the wheel-rail interface was easy to be congealed into water film after the warm and humid air flow,and the oxidation was slight and the area was wide.However,at high temperature,water vapor was easy to cause debris accumulation and local oxidation was obvious.Thus,the wear mechanism also changed significantly,from fatigue wear and abrasive wear under low temperature condition to oxidation wear,adhesion wear and fatigue wear under high temperature condition.Therefore,the behavior of train wheel-rail low adhesion induced by warm and humid airflows should be paid more attention,to ensure the safe and reliable operation of trains passing through instantaneous humid and hot environments such as tunnels in alpine regions.