Abstract Heterogeneous microstructures have been proposed to optimize the mechanical properties in the respect of strength and ductility synergy in many alloy systems. In this work, the multi-phase hetero-structured microstructure consisting of fine grains and coarse grains where the ferrite is embedded in the vicinity of the nano-grains was obtained by regulating the thermomechanical processing parameters. A yield strength of 1.2 GPa which is more than two times higher than the coarse grained counterpart with less uniform elongation loss is achieved in the multi-phase hetero-structured steel. The microscopic load transfer in this complex microstructure is investigated by the in situ high energy synchrotron X-ray diffraction. The persistent strain hardening is ascribed to the hetero-deformation induced stress associated with the joint activation of transformation-induced plasticity (TRIP) and twinning-induced plasticity (TWIP) effects. As a comparison, the single-phase hetero-structured steel exhibits little lower strength but higher uniform ductility.

中文翻译：

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确保奥氏体不锈钢的强度和延展性协同作用：单相或多相异质结构设计

摘要 为了优化许多合金体系中强度和延展性协同作用方面的机械性能，提出了非均质显微组织。在这项工作中，通过调节热机械加工参数获得了由细晶粒和粗晶粒组成的多相异质结构组织，其中铁素体嵌入纳米晶粒附近。在多相异质结构钢中实现了 1.2 GPa 的屈服强度，比具有较少均匀延伸率损失的粗晶粒对应物高两倍多。通过原位高能同步加速器 X 射线衍射研究了这种复杂微观结构中的微观载荷转移。持续应变硬化归因于与相变诱导塑性 (TRIP) 和孪晶诱导塑性 (TWIP) 效应的联合激活相关的异质变形诱导应力。相比之下，单相异质结构钢的强度略低，但均匀延展性较高。