对激光淬火U71Mn钢轨淬硬层和母材进行纳米压痕试验，由载荷-压深曲线计算得到弹性模量和纳米硬度；建立淬硬层纳米压痕的轴对称有限元模型，基于幂强化模型并结合迭代法对载荷-压深曲线进行反演分析，确定幂强化模型的材料参数，并对反演分析的有效性进行验证。结果表明：淬硬层的平均弹性模量和纳米硬度分别为220.3，11.8 GPa，与母材相比分别提高了4.9%和187.8%，且二者在淬硬层中分布较为均匀，仅在边界处发生突变；反演分析得到淬硬层的特征应力为3 146.0 MPa，特征应变为0.038，应变硬化指数为0.64，名义屈服强度为498.3 MPa；由反演分析得到的应力-应变曲线与给定参数确定的应力-应变曲线的吻合程度较高，说明此反演分析方法有效。

Nano-indentation tests were conducted on hardening layer and base metal of laser-quenched U71Mn steel rail, and then the elastic modulus and nanohardness were calculated from the load-depth curves. An axisymmetric finite element model for nano-indentation of the hardening layer was established, and then the material parameters for isotropic power-hardening model were determined by the reverse analysis of the load-depth curves on the basis of the isotropic power-hardening model combined with iterative method. The validity of the reverse analysis was verified. The results show that the average elastic modulus and nanohardness of the hardening layer were 220.3, 11.8 GPa, improved by 4.9%, 187.8% those of the base metal, respectively. The elastic modulus and nanohardness distributed relatively homogeneously in the hardening layer and only changed sharply at the boundary. By the reverse analysis, the representative stress of the hardening layer was 3 146.0 MPa, the representative strain was 0.038, the strain hardening index was 0.64, and the nominal yield strength was 498.3 MPa. The stress-strain curves obtained by the reverse analysis and determined by given parameters were highly consistent, indicating the validity of the reverse analysis method.