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以国内某钢厂的热轧高强度钢为研究对象,进行拉伸试验,利用OM和TEM分析了钢显微组织、第二相析出粒子形貌和尺寸等。结果表明,实验钢的屈服强度657 MPa、抗拉强度744 MPa、伸长率18.7%。微合金元素的加入使钢材晶粒明显细化,屈服强度的细晶强化增量为321.5 MPa,为提高材料强度的主要强化机制;研究析出的第二相粒子可知,基体中纳米级析出的(Nb,Ti)(C,N)粒子阻碍位错运动,是提高材料强度的主要机制之一,起到析出强化作用,屈服强度的析出强化量为78.58 MPa。
Tensile tests were conducted on hot-rolled high-strength steel at a steel mill in China. The microstructure of the steel was analyzed by OM and TEM, and the morphology and size of the precipitated particles in the second phase were analyzed. The results show that the yield strength of experimental steel is 657 MPa, tensile strength is 744 MPa and elongation is 18.7%. The addition of microalloying elements makes the grain of the steel significantly refined and the grain refinement increment of the yield strength is 321.5 MPa, which is the main strengthening mechanism for increasing the material strength. It can be seen from the analysis of the second-phase particles precipitated in the matrix that nano- Nb, Ti) (C, N) particles impede the dislocation movement, which is one of the main mechanisms to improve the material strength. The precipitation strengthening effect of precipitation hardening is 78.58 MPa.