低温对LZ50车轴钢短裂纹行为的影响  

Effect of low temperature on short crack behavior of LZ50 axle steel

作　　者：杨冰[1] 廖贞[1] 李一帆 肖守讷[1] 阳光武[1] 朱涛[1] 陈东东 YANG Bing;LIAO Zhen;LI Yifan;XIAO Shoune;YANG Guangwu;ZHU Tao;CHEN Dongdong(State Key Laboratory of Traction Power,Southwest Jiaotong University,Chengdu 610031,China)

机构地区：[1]西南交通大学牵引动力国家重点实验室,四川成都610031

出　　处：《中南大学学报（自然科学版）》2022年第5期1867-1876,共10页Journal of Central South University:Science and Technology

基　　金：国家自然科学基金资助项目(51675446);四川省国际科技创新合作项目(2022YFH0075);牵引动力国家重点实验室自主课题(2019TPL_T13)。

摘　　要：为了明确在低温环境下铁路车轴钢的疲劳短裂纹扩展行为,以LZ50钢为对象,依据冲击试验结果和材料S-N曲线,设计并完成不同低温环境下的疲劳短裂纹复型试验,采用包含多种微观结构障碍影响的短裂纹扩展率模型对试验结果进行拟合。研究结果表明:温度为-10,-30和-50℃的疲劳寿命分别为室温下的2.3,2.8和11.7倍,疲劳寿命随环境温度降低而大幅度提高;在微观短裂纹(MSC)阶段,裂纹扩展率受材料微观结构影响经历2次降速,在物理短裂纹(PSC)阶段,裂纹扩展率持续增加,且随温度降低而下降;LZ50车轴钢MSC和PSC阶段分界点对应的疲劳寿命分数为0.47左右,临界裂纹长度约为100μm,且材料韧脆转变对短裂纹行为影响不大;所采用的扩展率模型对不同温度下短裂纹试验结果均可得到较好的拟合效果。To clarify the fatigue short crack growth behavior of railway axle steel at low temperature,taking LZ50axle steel as the research object,the fatigue short crack replica tests under different low temperature conditions were designed and completed according to the results of impact test and S-N curve.The propagation rate model including the influence of various microstructure obstacles was used for fitting the test results.The results show that the fatigue life at-10,-30 and-50℃is 2.3,2.8 and 11.7 times of that at room temperature,respectively.The fatigue life increases greatly with the decrease of ambient temperature.At the microstructurally short crack(MSC)stage,the crack growth rate generally decreases twice due to the influence of material microstructures.At the physically small crack(PSC)stage,the crack growth rate continues to increase,and overall trend of crack growth curve decreases with the decrease of temperature.The cut-off points of MSC and PSC of LZ50 axle steel are about0.47 of the fatigue life fraction,and the critical crack length is about 100μm,and the effect of ductile-brittle transition on the short crack behavior is not significant.A good fitting effect can be obtained for the test results of short cracks at different temperatures using the propagation rate model.

关 键 词：LZ50车轴钢 低温环境 S-N曲线 疲劳短裂纹 扩展率 

分 类 号：U270.41[机械工程—车辆工程]