利用纳米压痕技术对不同晶粒尺寸无间隙原子钢（IF钢）晶界的微观力学性能进行表征，并测试了IF钢的维氏硬度和拉伸性能，分析了晶界微观力学性能对宏观力学性能的影响。结果表明：不同尺寸晶粒内的纳米压痕硬度和弹性模量基本一致，但晶粒尺寸较小试样的平均纳米压痕硬度约为3.12 GPa，比晶粒尺寸较大试样的（2.36 GPa）更高，平均模量约为205 GPa，低于晶粒尺寸较大试样的（210 GPa），晶粒尺寸较小试样的维氏硬度和抗拉强度明显高于晶粒尺寸较大试样的；晶界的纳米压痕硬度（3.25 GPa以上）比晶粒内的（2.61 GPa）更高而弹性模量略低是导致宏观力学性能差异的主要原因。

The micro-mechanical properties at grain boundaries of interstitial-free steel (IF steel) with different grain size were characterized by nanoindentation technique, and the Vickers hardness and tensile properties of the steel were tested. The effect of micro-mechanical properties at the grain boundaries on the macro-mechanical properties was discussed. The results show that the nanoindentation hardness and elastic modulus of the grains with different size were basically the same. The average nanoindentation hardness of the sample containing relatively fine grains was about 3.12 GPa, higher than that (2.36 GPa) with relatively coarse grains, and the elastic modulus was about 205 GPa, lower than that (210 GPa) with relatively coarse grains. The Vickers hardness and tensile strength of the sample containing relatively fine grains were also higher than those containing relatively coarse grains. The nanoindentation hardness at the grain boundaries (above 3.25 GPa) was higher than that (2.61 GPa) in the grains while the elastic modulus was slightly lower, which was the main reason for the difference between the macro-mechanical properties.