| U75V重轨钢弯曲疲劳裂纹扩展行为EI |
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| 引用本文： | 岑耀东,郭曜珲,马潇,陈林,包喜荣.U75V重轨钢弯曲疲劳裂纹扩展行为EI[J].材料工程,2023,51(1):122-129. |
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| 作者姓名： | 岑耀东 郭曜珲 马潇 陈林 包喜荣 |
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| 作者单位： | 内蒙古科技大学 材料与冶金学院, 内蒙古 包头 014010 |
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| 基金项目： | 国家自然科学基金(51361021);内蒙古自治区科技重大专项(ZDZX2018024);内蒙古科技大学创新基金(2019QDL-B06);内蒙古高等学校科学研究项目(NJZY20089) |
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| 摘 要： | 为明确珠光体钢轨的疲劳裂纹扩展行为,测定U75V重轨钢轧态和热处理态两种条件下的三点弯曲疲劳裂纹扩展速率,采用光学显微镜、扫描电镜、EBSD对钢轨的微观组织、片层、断口形貌及裂纹扩展轨迹进行观察。结果表明:轧态和热处理态钢轨的疲劳辉纹平均间距分别为253,215 nm,轧态钢轨的疲劳断口呈现解理台阶与河流花样形貌,且河流花样趋于合并,而热处理态钢轨的疲劳断口呈现大量的解理台阶及较多的微裂纹和撕裂棱,河流花样以支流为主;热处理态钢轨的疲劳裂纹扩展速率远低于轧态,到达裂纹失稳阶段也较滞后;轧态和热处理态钢轨的疲劳裂纹扩展都是以穿晶断裂为主的穿晶断裂和沿晶断裂混合扩展方式进行,轧态和热处理态钢轨的珠光体片层间距分别为272,148 nm,其中热处理态钢轨的珠光体片层细密且方向多样,存在显著的珠光体团簇,裂纹扩展轨迹中出现较多的分支裂纹和裂纹桥接现象,对扩展起到阻碍作用,是热处理态钢轨抗疲劳裂纹扩展能力优于轧态的重要原因。
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| 关 键 词： | 重轨钢 疲劳断裂 裂纹扩展 显微组织 |
| 收稿时间： | 2022-01-25 |
Bending fatigue crack propagation behavior of U75V heavy rail steel |
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| Yaodong CEN,Yaohui GUO,Xiao MA,Lin CHEN,Xirong BAO.Bending fatigue crack propagation behavior of U75V heavy rail steel[J].Journal of Materials Engineering,2023,51(1):122-129. |
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| Authors: | Yaodong CEN Yaohui GUO Xiao MA Lin CHEN Xirong BAO |
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| Affiliation: | School of Materials and Metallurgy, Inner Mongolia University of Science and Technology, Baotou 014010, Inner Mongolia, China |
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| Abstract: | In order to clarify the fatigue crack propagation behavior of pearlitic rail, the three-point bending fatigue crack propagation rate of U75V heavy rail steel in rolling state and heat treatment state was measured. The microstructure, lamella, fracture morphology and fatigue crack propagation trajectory of rail were observed by optical microscope, scanning electron microscope and EBSD. The results show that the average distance between fatigue striation of rolled and heat-treated rails is 252.5 nm and 215.4 nm, the fracture surface of rolled rail presents cleavage steps and river patterns, and the river patterns tend to merge.However, the fatigue fracture surface of the heat-treated rail presents a large number of cleavage steps, more microcracks and tear edges, and the river pattern is dominated by tributaries.The fatigue crack growth rate of heat-treated rail is much lower than that of rolled sample, and it is also slow to reach the stage of crack instability.The fatigue crack propagation mode of rolled and heat-treated rail is the mixed propagation mode of transgranular fracture and intergranular fracture dominated by transgranular fracture, the pearlite lamellae spacing of rolled and heat-treated rails is 272.2 nm and 148.4 nm respectively. The pearlite lamellae of heat-treated rails is fine and has various directions, while there are significant pearlite clusters in the heat-treated rail.There are many branch cracks and crack bridges in the crack growth path, which hinders the crack propagation in the heat-treated U75V heavy rail steel, which is an important reason why the fatigue crack propagation rate of the heat-treated rail is lower than that of the rolled rail. |
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| Keywords: | heavy rail steel fatigue fracture crack propagation microstructure |
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