Abstract To evaluate the deformation mechanism in Fe-20Mn-11.5Al-1.2C lightweight steel, the relationship between mechanical properties and microstructural evolution during deformation at room temperature was investigated. Although the wrought alloy under investigation was only subjected to conventional solution treatment at 1050 °C for 2 h, the microstructure consisted of intragranular nano-sized κ-carbides within a γ-matrix and intergranular micro-sized κ-carbides along grain boundaries. As a result, the alloy exhibited high yield and tensile strengths of 1187 MPa and 1233 MPa, respectively, and a relatively low ductility of 15.4%. A series of microanalyses by means of electron backscattered diffraction and transmission electron microscopy revealed the deformation and fracture mechanism. During tension, initial deformation of the softer γ-matrix containing nano-sized κ-carbides led to unidirectional shearing of the κ-carbides. Deformation of intergranular κ-carbides initiated at the interface with the γ-matrix due to stress concentration, resulting in a planar glide of super-partial dislocation pairs. Cracking initiated within the harder intergranular κ-carbides upon deformation and propagated to grain boundaries or within the γ-matrix until fracture.

中文翻译：

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晶间/晶内κ-碳化物对轻质Fe-20Mn-11.5Al-1.2C钢变形机制的影响

摘要 为了评价Fe-20Mn-11.5Al-1.2C轻钢的变形机理，研究了室温变形过程中力学性能与微观组织演变的关系。尽管所研究的可锻合金仅在 1050 °C 下进行了 2 小时的常规固溶处理，但其微观结构由 γ 基体中的晶粒内纳米级 κ-碳化物和沿晶界的晶粒间微米级 κ-碳化物组成。结果，该合金表现出分别为 1187 MPa 和 1233 MPa 的高屈服强度和抗拉强度，以及 15.4% 的相对较低的延展性。通过电子背散射衍射和透射电子显微镜的一系列显微分析揭示了变形和断裂机制。紧张时，含有纳米级 κ-碳化物的较软 γ-基质的初始变形导致 κ-碳化物的单向剪切。由于应力集中，在与 γ 基体的界面处开始晶间 κ-碳化物变形，导致超偏位错对的平面滑移。变形时在较硬的晶间 κ-碳化物内开始开裂，并传播到晶界或 γ-基质内直至断裂。