Laser shock peening (LSP) is a surface treatment technique that forms a strengthened layer on the metal surfaces. In this study, the LSP was applied on the locomotive LZ50 axle steel surface which was interference fitted with the wheel. The microstructures, fracture morphologies and fatigue performances of LSP‐treated and untreated axle steels were explored. The results indicated that after the LSP treatment, a strengthened layer was generated on the axle steel surface. The surface hardness was increased by 25%, that is, from around 204 to around 255 HV_0.3. The residual compressive stresses were improved from 260 to 345 MPa along the axial direction and from 165 to 225 MPa along the radial direction. The fatigue limit was increased by 30%, that is, from around 130 to around 170 MPa. The fracture surfaces could be divided into three regions: crack initiation, crack propagation, and short‐break regions. In the crack initiation region, the fatigue striation of the LSP‐treated steel was denser than the untreated steel. In the crack propagation and short‐break regions, the fracture morphologies of the LSP‐treated and the untreated axle steels were similar.

中文翻译：

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激光冲击喷丸对铁路轮对LZ50车轴钢疲劳性能的影响

激光冲击喷丸（LSP）是一种表面处理技术，可在金属表面形成强化层。在这项研究中，LSP被应用于与车轮过盈配合的机车LZ50车轴钢表面。探讨了经LSP处理和未处理的车轴钢的显微组织，断裂形态和疲劳性能。结果表明，经过LSP处理后，车轴钢表面产生了一层强化层。表面硬度提高了25％，即从204左右提高到255 HV _0.3。沿轴向的残余压缩应力从260 MPa提高到345 MPa，沿径向的残余压缩应力从165 MPa提高到225 MPa。疲劳极限增加了30％，即从大约130 MPa增大到大约170 MPa。断裂表面可分为三个区域：裂纹萌生，裂纹扩展和短断裂区域。在裂纹萌生区域，经LSP处理的钢的疲劳条纹比未处理的钢致密。在裂纹扩展和短裂纹区域，经LSP处理和未经处理的车轴钢的断裂形态相似。