低温下高速车轮材料滚动磨损与疲劳损伤行为

利用低温环境轮轨磨损模拟试验装置，研究了高速铁路车轮材料在室温及低温环境下的滚动接触疲劳损伤行为。结果表明：低湿度的低温环境导致车轮材料磨损率、塑性变形及疲劳损伤较室温下明显加重。随试验温度的降低，轮轨摩擦因数、磨损率及表面硬度均呈现先急剧上升后轻微下降趋势。室温工况下磨痕表面有严重的犁沟现象，而低温工况下车轮试样表面以疲劳裂纹及剥落损伤为主。随着温度的降低，磨损形式由氧化磨损、磨粒磨损逐渐向疲劳及粘着磨损转变。车轮材料裂纹主要沿较软的铁素体线扩展，室温下剖面损伤较轻微。低温工况下由于车轮材料发生脆化，珠光体呈现不同于室温下的形貌及分布特性。在低温下，表层裂纹扩展角度及次表层裂纹长度增加，同时表层裂纹易于汇合并产生分支。

Rolling Wear and Fatigue Damage Behavior of High-speed Wheel Materials at Low Temperature

The rolling contact fatigue damage behaviors of high-speed railway wheel material at room and low temperatures are studied by using wheel/rail rolling wear simulation experiment device under low temperature environment. The results show that the low humidity leads to the increase of wear rate, plastic deformation and fatigue damage at low temperature. With the temperature decreasing, the friction coefficient, wear rate and surface hardness show a sharp rise trend and then slight decline. The ploughing dominates on the wheel surface at room temperature, while fatigue crack and peeling at low temperature. With the decrease of temperature, wear mode changes gradually from oxidation wear, abrasive wear to the fatigue wear and adhesive wear. The crack of wheel roller mainly propagates along the soft ferrite line and the profile damage is mild at room temperature. Due to the embrittlement of wheel material at low temperature, the morphology and distribution characteristics of pearlite is different from that at room temperature. At low temperature, the angle of surface crack and length of subsurface crack increases, moreover, the surface crack merges with adjacent cracks easily and branching occurs.