The strengthening mechanism of microalloyed vanadium (V) on eutectoid pearlite steel was investigated from the perspectives of nano-precipitation and lattice strain. The 0.2% proof stress of specimens, isothermally transformed at 873 K, increased by about 160–170 MPa with the addition of 0.1% V. However, the interphase precipitation of vanadium carbide (VC), regarded as the principal strengthening factor, was detected neither by transmission electron microscopy nor by 3D atom probe microscopy (3D-AP). A lattice strain in lamellar ferrite, analyzed by broadening of the X-ray diffraction peak, has been experimentally estimated to understand the strengthening mechanisms by V-addition. The lattice strain data of 0.1% V-added pearlite specimens were plotted on the same correlation line as those of the V-free specimens with proof stress. In addition, the elemental map obtained by 3D-AP showed that V atoms concentrate in lamellar cementite rather than ferrite, which could change the cementite lattice parameters and gain ferrite/cementite misfit, causing lattice strain increment. These results revealed that microalloyed V influences not only VC precipitation in lamellar ferrite but also the lattice strain increment in pearlite lamellar. In the case of pearlite steels containing at most 0.1% V, lattice strain was considered the major factor of their yield behaviors. Furthermore, 0.1% V addition did not enhance work-hardening behavior as notably as that estimated by Ashby’s work-hardening theory of dispersion-hardened crystals. Therefore, VC precipitation is not necessary for the V strengthening effect on pearlite steel.

从纳米沉淀和晶格应变的角度研究了微合金化钒在共析珠光体钢上的强化机理。在873 K等温转变的试样的0.2％屈服强度在添加0.1％V的情况下增加了约160–170 MPa。但是，检测到碳化钒（VC）的相间沉淀是主要的增强因子，既不是通过透射电子显微镜，也不是通过3D原子探针显微镜（3D-AP）。通过X射线衍射峰的加宽分析，对层状铁素体中的晶格应变进行了实验估算，以了解通过添加V的强化机理。将添加0.1％V的珠光体样品的晶格应变数据绘制在与不含V的具有屈服应力的样品相同的相关线上。此外，通过3D-AP获得的元素图表明，V原子集中在层状渗碳体中而不是铁素体中，这可以改变渗碳体的晶格参数并获得铁素体/渗碳体的失配，从而导致晶格应变增加。这些结果表明，微合金化的V不仅影响层状铁素体中的VC沉淀，而且影响珠光体层状体中的晶格应变增加。在珠光体钢中，V含量最高为0.1％时，晶格应变被认为是其屈服行为的主要因素。此外，添加0.1％的V不能显着增强工作硬化行为，正如Ashby的弥散硬化晶体的工作硬化理论所估计的那样。因此，VC沉淀对于珠光体钢上的V强化作用不是必需的。