利用光学显微镜、拉伸试验机和透射电镜等研究了锰、铌元素含量调整前后热轧酸洗QStE500TM钢板的组织和性能，分析了不同强化机制及强化效果。结果表明：将锰、铌元素质量分数分别由1.6%，0.050%降至1.3%，0.035%后，试验钢板的显微组织均由铁素体构成，晶粒度均为13.5级，屈服强度由621 MPa降至574 MPa，抗拉强度由654 MPa降至611 MPa；当锰质量分数降低0.3%时，其固溶强化效果降低11.1 MPa，铌质量分数降低0.015%时，Nb-Ti-C第二相粒子的析出数量减少，析出强化效果降低35.9 MPa。

The microstructure and property of hot-rolled pickling steel plate QStE500TM before and after Mn, Nb content adjustment were studied using optical microscope, tensile testing machine and transmission electron microscope. The different strengthening mechanisms and strengthening effects were analyzed. The results show that after decreasing the mass fractions of Mn and Nb from 1.6%, 0.050% to 1.3%, 0.035%, respectively, the microstructures of tested steel plates were both composed of ferrite with the grain size of grade 13.5. Furthermore, the yield strength decreased from 621 MPa to 574 MPa and the tensile strength from 654 MPa to 611 MPa. When the mass fraction of Mn decreased by 0.3%, the solid solution strengthening effect declined 11.1 MPa. When the mass fraction of Nb decreased by 0.015%, the precipitation amount of Nb-Ti-C second phase particles dropped. The precipitation strengthening effect declined 35.9 MPa.