This article summarizes the state of the art of the comprehensive strengthening mechanism of steel. By using chemical phase analysis, X-ray small-angle scattering (XSAS), room temperature organic (RTO) solution electrolysis and metal embedded sections micron-nano-meter characterization method, and high-resolution transmission electron microscopy (TEM) observation, the properties of nanoscale cementite precipitates in Ti microalloyed high-strength weathering steels produced by the thin slab continuous casting and rolling process were analyzed. Except nanoscale TiC, cementite precipitates with size less than 36 nm and high volume fraction were also found in Ti microalloyed high-strength weathering steels. The volume fraction of cementite with size less than 36 nm is 4.4 times as much as that of TiC of the same size. Cementite with high volume fraction has a stronger precipitation strengthening effect than that of nanoscale TiC, which cannot be ignored. The precipitation strengthening contributions of nanoscale precipitates of different types and sizes should be calculated, respectively, according to the mechanisms of shearing and dislocation bypass, and then be added with the contributions of solid solution strengthening and grain refinement strengthening. A formula for calculating the yield strength of low-carbon steel was proposed; the calculated yield strength considering the precipitation strengthening contributions of nanoscale precipitates and the comprehensive strengthening mechanism of steels matches the experimental results well. The calculated σ s = 630 to 676 MPa, while the examined σ s = 630 to 680 MPa. The reason that “ultrafine grain strengthening can not be directly added with dislocation strengthening or precipitation strengthening” and the influence of the phase transformation on steel strength were discussed. The applications for comprehensive strengthening theory were summarized, and several scientific questions for further study were pointed out.
展开▼
机译：本文总结了钢的综合强化机理的最新技术。通过化学相分析，X射线小角散射（XSAS），室温有机（RTO）溶液电解和金属嵌入切片的微米-纳米表征方法以及高分辨率透射电子显微镜（TEM）观察，分析了薄板坯连铸连轧工艺生产的Ti微合金高强度耐候钢中纳米渗碳体的析出行为。除纳米级TiC外，在Ti微合金化高强度耐候钢中还发现了尺寸小于36 nm且体积分数高的渗碳体沉淀物。尺寸小于36nm的渗碳体的体积分数是相同尺寸的TiC的4.4倍。体积分数高的渗碳体比纳米TiC具有更强的析出强化作用，这是不容忽视的。应根据剪切和位错绕过的机理，分别计算出不同类型和尺寸的纳米级沉淀物的沉淀增强作用，然后加入固溶强化和晶粒细化强化作用。提出了计算低碳钢屈服强度的公式。在考虑纳米级析出物的析出强化作用的基础上计算出的屈服强度以及钢的综合强化机理与实验结果吻合良好。计算得出的σ s = 630至676 MPa，而检查的σ s = 630至680 MPa。讨论了“不能通过位错强化或析出强化不能直接添加超细晶粒强化”的原因以及相变对钢强度的影响。总结了综合强化理论的应用，指出了一些需要进一步研究的科学问题。
展开▼
