Table 2 Parameters of the martensite used as input for the TC-Prisma simulation.
表 2 马氏体参数，用作 TC-Prisma 模拟的输入。

Fig. 16a demonstrates that both the Homo-coarse and Homo-fine models exhibit significantly higher normalized driving forces for nucleation, primarily due to elevated Gibbs free energies resulting from high C ( ) and Mn (3.83 wt. ) contents. With the assistance of more dislocation density in the Homo-fine model, it presents larger nucleation rate (Fig. 16b) and faster precipitation kinetics than the Homo-coarse model (Fig. 16c). Conversely, a reduction in Mn content ( vs. 3.83 wt. %) markedly impedes precipitation in Heter-fine model, even at much higher dislocation density , underscoring the strong retard effect of Mn heterogeneity on carbide precipitation. The nucleation rate and precipitation kinetics are further retarded in the C&Heter-fine model when taking the carbon depletion in martensite into consideration (red line in Fig. 16(b, c)). Moreover, the volume fraction of carbide precipitation in C&Heter-fine model is noticeably reduced (Fig. 16c).
图 16a 表明，Homo-coarse 和 Homo-fine 模型均表现出明显更高的成核驱动力，主要是由于高 C（ ）和 Mn（3.83 wt. ）含量导致的较高吉布斯自由能。在 Homo-fine 模型中，更多的位错密度 的帮助下，它呈现出比 Homo-coarse 模型更大的成核速率（图 16b）和更快的沉淀动力学（图 16c）。相反，Mn 含量的降低（ vs. 3.83 wt. %）显著阻碍了 Heter-fine 模型中的沉淀，即使在更高的位错密度 下，突出了 Mn 异质性对碳化物沉淀的强烈阻滞效应。在考虑马氏体中碳耗尽时，C&Heter-fine 模型中的成核速率和沉淀动力学进一步受到抑制（图 16（b，c）中的红线）。此外，C&Heter-fine 模型中的碳化物沉淀体积分数明显减少（图 16c）。

(a)

(b)

Fig. 16. Evolution of carbide precipitation during partitioning at : (a) normalized driving force; (b) nucleation rate; and (c) precipitation fraction.
图 16. 在 时的分配过程中碳化物沉淀的演变：（a）标准驱动力；（b）成核速率；和（c）沉淀分数。

On one hand, from a thermodynamic perspective, the precipitation of transition carbides in martensite during partitioning stage is inevitable in both the NM and GP regions; however, the substantial depletion of and elements significantly diminishes the driving force, nucleation rate, and volume fraction of transition carbides in martensite (Fig. 16). On the other hand, there is a kinetic competition between carbide precipitation and carbon diffusion into austenite. The DICTRA simulation indicates that both the nanoscale structure and high dislocation density in GP region accelerate the diffusion of carbon atoms from martensite to austenite (Fig. 14, Fig. 15).
从热力学的角度来看，在分配阶段马氏体中的过渡碳化物沉淀在 NM 和 GP 区域都是不可避免的；然而， 和 元素的大量耗尽显著减小了过渡碳化物在马氏体中的驱动力、成核速率和体积分数（图 16）。另一方面，碳化物沉淀和碳在奥氏体中的扩散之间存在动力学竞争。DICTRA 模拟表明，GP 区域中的纳米级结构和高位错密度加速了碳原子从马氏体向奥氏体的扩散（图 14，图 15）。

Therefore, it can be concluded that the depletion of and in lath martensite reduces the driving force for carbide formation while nanoscale structure and high dislocation density accelerate the carbon diffusion from martensite to austenite, leading to that the carbon atoms in martensite within the GP region prefer to diffuse into austenite rather than to form carbides.
因此，可以得出结论，马氏体板条中 和 的耗尽减小了碳化物形成的驱动力，而纳米级结构和高位错密度加速了碳从马氏体向奥氏体的扩散，导致 GP 区域内的马氏体中的碳原子更倾向于扩散到奥氏体而不是形成碳化物。

The fundamental design principle of the process focuses on stabilizing a large fraction of austenite to facilitate TRIP effect. This stabilization is primarily achieved through carbon partitioning from martensite. However, the competing reactions during the partitioning stage, such as carbide precipitation, are detrimental to fraction and stability of RA. Therefore, many Q&P process variants have been developed to inhibit these competitive reactions, so as to enhance the efficient utilization of carbon atoms in stabilizing austenite. The carbon atoms occupied by austenite can be calculated using the following equation:
工艺的基本设计原则侧重于稳定化大部分奥氏体以促进 TRIP 效应。这种稳定化主要通过从马氏体中的碳分配来实现。然而，在分配阶段的竞争反应，如碳化物沉淀，对 RA 的分数和稳定性是有害的。因此，许多 Q&P 工艺变种已经被开发出来，以抑制这些竞争反应，从而增强碳原子在稳定奥氏体中的高效利用。奥氏体中占据的碳原子可以使用以下方程计算：

where is the carbon content of RA, in mole fraction; is the carbon content of the investigated steel, in mole fraction; is fraction, in volume fraction. The elemental concentrations, which are adopted for the calculation of carbon partitioning efficiency, are summarized in Table 3. As shown in Fig. 17, the GP region exhibits a higher carbon atoms utilization efficiency than NM region. Specifically, the
其中 是 RA 的碳含量，以摩尔分数表示； 是被调查钢的碳含量，以摩尔分数表示； 是 分数，以体积分数表示。用于计算碳分配效率的元素浓度总结在表 3 中。如图 17 所示，GP 区域的碳原子利用效率高于 NM 区域。具体来说，
measured carbon content in martensite is lower in GP region (Fig. 17a), while the carbon content occupied by RA is significantly higher (Fig. 17b). As can be seen, introducing Mn-heterogeneous austenite into the process provides an innovative approach to promote the carbon partitioning from martensite to RA through inhibiting carbide precipitation.
马氏体中的碳含量在 GP 区域较低（图 17a），而在 RA 中占据的碳含量显著较高（图 17b）。可以看出，引入锰非均质奥氏体到 过程中提供了一种创新方法，通过抑制碳化物沉淀促进从马氏体到 RA 的碳分配。

(a)

(b)

Fig. 17. The carbon content in quenching and partitioning steels: (a) martensite; (b) carbon occupied by retained austenite. The black dot represents the APT data in Refs. ; the grey dot represents the XRD data in Refs. . The steel is the present investigated (wt.%) steel; the steel is the previously investigated (wt.%) steel is ghost pearlite; is normal martensite.
图 17。淬火和分配钢中的碳含量：（a）马氏体；（b）被保留奥氏体占据的碳。黑点代表参考文献中的 APT 数据 ；灰点代表参考文献中的 XRD 数据 。 钢是目前研究的 （重量百分比）钢； 钢是先前研究的 （重量百分比）钢 是幽灵珠光体； 是普通马氏体。

Table 3 C concentration, Mn concentration and calculated s temperature in the GP region and NM region.
表 3 GP 区域和 NM 区域中的 C 浓度、Mn 浓度和计算 s 温度。

In terms of mechanical performance, the RA and its corresponding TRIP effect play important roles in Q&P steels . To fully understand the TRIP effect, the fraction, morphology and stability of RA should be carefully studied. As shown in Table 3, the RA stability can be indicated by the temperature calculated as follows :
在机械性能方面，RA 及其对应的 TRIP 效应在 Q&P 钢中起着重要作用 。要充分理解 TRIP 效应，就必须仔细研究 RA 的质量分数、形态和稳定性。如表 3 所示，RA 的稳定性可以通过以下计算得出的 温度来表示 ：

where is the mass fraction of element . As demonstrated by our previous study , the ductility is improved through constructing Mn heterogeneity. Similarly, the ductility is also improved by Mn heterogeneity in present study, where the uniform elongation of PPQ&P130 sample is higher than CQ&P130 sample (12.5 vs. ). Due to the enrichment of carbon and Mn atoms, the temperature of RA is significantly lower in GP region than NM region vs. ), indicating much stronger stability in the former. Taking the grain size of RA into consideration, the difference in RA stability between GP region and NM region is enlarged because the in GP region is much smaller than NM region (47.5 4.4
其中 是元素 的质量分数。正如我们之前的研究所示 ，通过构建 Mn 的不均匀性来提高延展性。类似地，在本研究中，通过 Mn 的不均匀性也提高了延展性，其中 PPQ&P130 样品的均匀延伸率高于 CQ&P130 样品（12.5 vs. ）。由于碳和 Mn 原子的富集，GP 区域的 RA 温度明显低于 NM 区域 vs. ），表明前者的稳定性更强。考虑 RA 的晶粒尺寸，GP 区域和 NM 区域之间 RA 稳定性的差异扩大，因为 GP 区域的 要比 NM 区域小得多（47.5 4.4）。
nm vs. . When deformed at the early stage, more RA are quickly transformed into martensite in CQ&P130 sample than PPQ&P130 sample, as evidenced by more TRIP effect in the former (Fig. 12b). These two samples have similar RA fraction of around . In our previous study , it has been demonstrated that the blocky RA in NM region is transformed earlier using interrupted tension; with further deformation, the RA-to-martensite transformation is dominant by film RA in GP region. Due to larger fraction of GP region and, in turn, film RA (Fig. 5), the PPQ&P130 sample exhibits sustainable TRIP effect than CQ&P130 sample, leading to larger uniform elongation (Fig. 12b). Compared with CQ&P130 sample, the yield strength of PPQ&P130 sample is increased by and it is predominantly ascribed to the refinement of lath martensite, which has been illustrated in our previous study . As a result, the PPQ&P130 sample presents a better combination of strength and ductility.
在早期变形时，CQ&P130 样品中的更多 RA 比 PPQ&P130 样品更快地转变为马氏体，这一点在前者的 TRIP 效应更明显（图 12b）。这两个样品的 RA 分数约为 。在我们之前的研究中 ，已经证明 NM 区域中的块状 RA 在使用中断张力时更早地转变；随着进一步变形，GP 区域中的薄膜 RA 主导了 RA 到马氏体的转变。由于 GP 区域和薄膜 RA 的比例更大（图 5），PPQ&P130 样品比 CQ&P130 样品表现出更持久的 TRIP 效应，导致更大的均匀延伸（图 12b）。与 CQ&P130 样品相比，PPQ&P130 样品的屈服强度提高了 ，主要归因于板条马氏体的细化，这在我们之前的研究中已经说明 。因此，PPQ&P130 样品呈现出更好的强度和延展性的组合。

In the present study, alternative Mn-enriched RA film and Mn-depleted martensite lath are purposely obtained through quenching and partitioning from -heterogeneous high-temperature austenite deliberately inherited from Mn-partitioned lamellar pearlite. The effect of Mn heterogeneity on carbon partitioning is systematically investigated, leading to the following conclusions.
在本研究中，通过淬火和分配从 继承的异质高温奥氏体中故意获得富锰 RA 薄膜和贫锰马氏体板条。系统地研究了锰的异质对碳的分配的影响，得出以下结论。

(1) Through introducing Mn heterogeneity in high-temperature austenite prior to quenching and partitioning, the ghost pearlite consisting of Mn-enriched RA and Mn-
(1) 通过在淬火和分配之前在高温奥氏体中引入锰异质性，形成由富锰 RA 和富锰幽灵珠光体组成。