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对U71Mn进行高能喷丸试验,并借助扫描电镜、透射电镜、硬度仪等对运行后U71Mn钢轨和喷丸后U71Mn钢表层微观组织演变规律和硬度分布进行了对比分析。结果表明:实际运行后,U71Mn钢轨表层硬度值达到410 HV,变形层厚度约200μm,踏面有大量剥落,最表层已没有片状珠光体组织的形貌特点,渗碳体扭曲、碎化、溶解。喷丸处理表层变形和硬化均匀,表层显微硬度随喷丸时间的延长而增大,喷丸1 h表层硬度可达340 HV。在0.5~1 h喷丸处理样品中没有裂纹和剥落,表层组织比运行后表层组织变形程度大,组织组成基本相同。3 h喷丸时表层观察到纳米层,铁素体晶粒细化至约60 nm。
The high-energy shot peening test was carried out on U71Mn. The microstructure evolution and hardness distribution of the U71Mn rail and the U71Mn steel after shot peening were analyzed by SEM, TEM and hardness tester. The results show that after actual operation, the surface hardness of the U71Mn rail reaches 410 HV, the deformation layer thickness is about 200 μm, the tread surface has a lot of flaking, the topmost layer has no morphological features of lamellar pearlite structure, and the distortion, fragmentation and dissolution of cementite . Shot peening deformation and surface hardening uniform, surface microhardness increases with the shot peening time, shot peening 1 h surface hardness up to 340 HV. In 0.5 ~ 1 h shot peening samples without cracks and spalling, the surface tissue than after running surface tissue deformation degree, the same organization. 3 h peening surface layer was observed when the nano-ferrite grain refinement to about 60 nm.