钢轨硬度对疲劳裂纹萌生和钢轨磨耗的影响

Effect of Rail Hardness on Fatigue Cracks Initiation and Rail Wear

为了研究钢轨磨耗和疲劳裂纹萌生寿命与钢轨硬度的关系,基于Archard磨耗模型和临界平面法疲劳裂纹萌生预测模型,结合磨耗和型面变化分段迭代和疲劳损伤累积,提出了钢轨疲劳裂纹萌生和磨耗共存预测方法;对4种不同硬度钢轨的磨耗发展、疲劳损伤累积以及疲劳裂纹萌生寿命进行研究.结果表明:该方法预测的裂纹萌生寿命与现场观测结果有较好的吻合性;高硬度钢轨可以降低磨耗、延长疲劳裂纹萌生寿命,适合在小半径曲线上应用;4种硬度的钢轨中,钢轨硬度每提高10 HBW,平均磨耗发展率将降低约3%~6%,疲劳裂纹萌生寿命延长约9%~12%;对比U78CrV/U76CrRE热轧钢轨,U78CrV热处理钢轨的平均硬度值增加了17.9%,磨耗发展率降低了约19.8%,疲劳裂纹萌生寿命延长了约57.7%;在轮轨摩擦系数为0.3时,4种钢轨的疲劳裂纹均萌生于轨面1.0~2.5 mm以下的亚表面范围内,距离轨顶中心15~18 mm.

In order to study the relationship between rail hardness and rail wear and fatigue cracks initiation life,based on the Archard wear model and the critical plane fatigue cracks initiation prediction model,the prediction method for the coexistence of rail fatigue cracks initiation and wear was presented by combining wear and sectional iteration of profile changes and fatigue damage accumulation. The wear growth, fatigue damage accumulation and fatigue cracks initiation life of 4 kinds of rails with different hardness were researched. The results show that the fatigue cracks initiation life predicted by above-mentioned method has a good agreement with that of the field observation. The rail with high hardness can reduce wear and prolong the fatigue cracks initiation life,which is suitable for sharp curves. Among the rails with four hardness,the average wear growth rate can be reduced by about 3%-6% and the fatigue cracks initiation life can be prolonged by about 9%-12%when the hardness of the rail increases by every 10 HBW. Comparing to the U78 CrV/U76 CrRE hot rolled rail,the average hardness of the U78 CrV heat-treated rail increases by about 17.9% while the wear growth rate reduces by about 19.8% and its fatigue cracks initiation life prolongs by about 57.7%. With the wheel/rail friction coefficient of 0.3,the fatigue cracks are initiated at rail sub-surface which is below rail surface of about 1.0-2.5 mm and close to rail top center of about 15-18 mm in all 4 kinds of rails.