采用Thermo-Calc热力学软件计算不同碳含量与复合添加铝、硼后低碳钢的热力学平衡相图，研究了碳、铝、硼元素在试验钢中的固溶、析出行为以及试验钢的显微组织、力学性能和抗时效性能。结果表明：当碳质量分数由0.003%增至0.020%时，试验钢基体中固溶的自由碳原子含量增加；而当碳质量分数增至0.053%时，钢中渗碳体的析出量增加，固溶的自由碳原子减少；复合添加铝+硼后，钢中的氮原子以AlN与BN形式析出，固溶的自由氮原子减少；碳含量以及铝+硼的复合添加对试验钢室温拉伸性能影响较小；随着碳含量的增加，试验钢的晶粒尺寸减小，时效指数先增大后减小；当碳质量分数为0.020%时，试验钢抗时效性能最差，复合添加适量硼+铝有助于改善低碳钢抗时效性能。

Thermodynamic equilibrium phase diagram of low carbon steel with different carbon content and combined addition of aluminum and boron was calculated through the Thermo-Calc thermodynamic software. The solid solution and precipitation behaviors of carbon, aluminum, and boron elements in the low carbon steel, as well as the microstructure, mechanical properties and anti-aging properties of the test steel, were studied. The results show that the content of dissolved free carbon atom in the test steel matrix increased with the carbon mass fraction from 0.003% to 0.020%. When the carbon mass fraction increased to 0.053%, the precipitation of cementite in the steel increased and the dissolved free carbon atom decreased. After the combined addition of aluminum and boron in the low carbon steel, the nitrogen atom precipitated in the form of AlN and BN, resulting in the decrease of the dissolved free nitrogen atom. The carbon content and combined addition of aluminum and boron had little effect on the tensile properties of the test steel at room temperature. With increasing carbon content, the grain size of the test steel decreased gradually, and the aging index increased first and then decreased. The test steel showed the worst aging resistance at the carbon mass fraction of 0.020%, and the combined addition of boron and aluminum could improve its aging resistance.