水润滑条件下转速对车轮钢滚动接触疲劳和磨损性能的影响

Effect of Rotational Speed on Rolling Contact Fatigue and Wear Properties of Wheel Steel under Water Lubrication

为探究水润滑条件下转速对车轮钢滚动接触疲劳和磨损性能的影响,利用滚动接触摩擦磨损试验测试不同转速下车轮试样的剥离寿命、摩擦因数和磨损率,并结合磨损形貌和裂纹扩展形貌观察,对比分析不同转速下摩擦磨损和剥离寿命的影响因素。结果表明:随转速提高,车轮材料氧化程度加剧,导致摩擦因数逐渐增加;当转速由250 r/min增至500 r/min时,摩擦因数增幅较小,应变速率增加导致磨损率下降,当转速由500 r/min增至1000 r/min时,摩擦因数急剧增加,导致材料磨损率增加;随转速提高,剖面塑性流动层厚度、裂纹扩展角度、裂纹分叉深度和最大扩展深度均呈现减小趋势。转速增加带来的摩擦因数的增加,一方面缩短裂纹萌生寿命,另一方面减小了裂纹发生向上转折的深度,最终导致滚动接触疲劳寿命随转速的增加而减小。

In order to investigate the effect of rotational speed on rolling contact fatigue and wear properties of wheel steel under water lubrication,the spalling life,friction coefficient and wear rate of wheel steel samples at different rotational speeds were measured by rolling-sliding test.Based on the observation of wear morphology and crack growth morphology,the influence factors of spalling life,friction and wear at different rotational speeds were compared and analyzed.The results show that the oxidation degree of wheel material as well as the friction coefficient are gradually increased with the increase of rotational speed.When the rotational speed is increased from 250 r/min to 500 r/min,the friction coefficient is increased slightly,and the wear rate is decreased due to the increase of strain rate.When the rotational speed is increased from 500 r/min to 1000 r/min,the wear rate is increased because of the sharp increase of friction coefficient.With the increase of rotational speed,the thickness of plastic flow layer,crack propagation angle,crack branching depth and maximum crack propagation depth show a decreasing trend.The increase of friction coefficient caused by the increase of rotational speed not only shortens the crack initiation life,but also reduces crack branching depth,which leads to the decrease of rolling contact fatigue life with the increase of rotational speeds.