Manipulating chemical heterogeneity, which could substantially alter austenite decomposition behavior upon cooling, has recently proven to be very effective in tailoring retained austenite and architecting novel microstructures in steels. However, the mechanistic role of chemical heterogeneity in austenite decomposition and stabilization has not been fully understood, and its potential in microstructural architecting in commercial advanced high strength steels (AHSSs) has not been explored. In this study, we investigate the potential effects of Mn heterogeneity, which originates from the starting microstructure of Mn-lean ferrite and Mn-rich cementite, on austenite decomposition and stabilization in a commercial Quenching and Partitioning (Q&P980) steel. It is interestingly found that there is a strong kinetic interaction between the Mn enriched region in austenite and the migrating austenite/ferrite interface upon cooling, and phase field model predicts that the austenite/ferrite interface could migrate through the Mn-rich region via either a cutting through or by-passing manner, depending on the absolute Mn content of the Mn-rich region and the degree of Mn heterogeneity. The by-passing interaction could substantially promote C partitioning into the Mn-rich region, which further enhances the region's stability. The current study demonstrates austenite decomposition and C partitioning behavior can even be altered by a weak Mn heterogeneity, which needs to be carefully considered in the future design of AHSSs.

控制化学异质性可以显着改变冷却时奥氏体的分解行为，最近已被证明在调整钢中的残余奥氏体和构建新型微观结构方面非常有效。然而，化学异质性在奥氏体分解和稳定化中的机理作用尚未完全了解，其在商业先进高强度钢 (AHSS) 微观结构设计中的潜力尚未得到探索。在这项研究中，我们研究了源自贫锰铁素体和富锰渗碳体起始微观结构的锰不均匀性对商业淬火和分配 (Q&P980) 钢中奥氏体分解和稳定的潜在影响。有趣的是，冷却时奥氏体中的富锰区与迁移的奥氏体/铁素体界面之间存在强烈的动力学相互作用，相场模型预测奥氏体/铁素体界面可以通过以下两种方式迁移通过富锰区：切通或旁路方式，取决于富Mn区Mn的绝对含量和Mn的不均匀程度。旁路相互作用可以显着促进 C 分配到富 Mn 区域，从而进一步增强该区域的稳定性。目前的研究表明，奥氏体分解和 C 分配行为甚至可以被微弱的 Mn 异质性改变，这需要在未来的 AHSS 设计中仔细考虑。相场模型预测奥氏体/铁素体界面可以通过切穿或旁路方式迁移通过富锰区，这取决于富锰区的绝对锰含量和锰的不均匀程度。旁路相互作用可以显着促进 C 分配到富 Mn 区域，从而进一步增强该区域的稳定性。目前的研究表明，奥氏体分解和 C 分配行为甚至可以被微弱的 Mn 异质性改变，这需要在未来的 AHSS 设计中仔细考虑。相场模型预测奥氏体/铁素体界面可以通过切穿或旁路方式迁移通过富锰区，这取决于富锰区的绝对锰含量和锰的不均匀程度。旁路相互作用可以显着促进 C 分配到富 Mn 区域，从而进一步增强该区域的稳定性。目前的研究表明，奥氏体分解和 C 分配行为甚至可以被微弱的 Mn 异质性改变，这需要在未来的 AHSS 设计中仔细考虑。旁路相互作用可以显着促进 C 分配到富 Mn 区域，从而进一步增强该区域的稳定性。目前的研究表明，奥氏体分解和 C 分配行为甚至可以被微弱的 Mn 异质性改变，这需要在未来的 AHSS 设计中仔细考虑。旁路相互作用可以显着促进 C 分配到富 Mn 区域，从而进一步增强该区域的稳定性。目前的研究表明，奥氏体分解和 C 分配行为甚至可以被微弱的 Mn 异质性改变，这需要在未来的 AHSS 设计中仔细考虑。