Hot isostatic pressing (HIP) has emerged as a highly effective and extensively adopted technique for eliminating intrinsic flaws, mitigating residual stress, and addressing microstructural anisotropy in laser powder bed fused (L-PBF) metallic materials. However, the deformation behavior, strengthening mechanism, and associated mechanistic models of HIPed l-PBF austenitic steel remain largely unclear. Through multiple microstructural characterizations, this study determined that the primary deformation mechanism of HIPed l-PBF austenitic steel involved the emission of twinning partials from either the annealing twin boundaries or high-angle grain boundaries (HAGBs) with the decoration of extra dislocations and prismatic inclusions. A twinning propensity model was formulated based on the identified deformation mechanisms, revealing that the critical angle () for twinning partial emissions ranged from 25.64° to 28.46° By incorporating the mathematical relationship describing the force equilibrium state between trailing and twinning partials, a twinnability map considering both the crystallographic orientation and stress state (magnitude and direction) was established to guide the twinning control for desired mechanical properties. Finally, the accuracy of the twinning model and twinnability map was effectively confirmed using the microstructural results, whereas the limitations of the twinning model and twinnability map were reasonably examined through micro-defect and texture analysis. The results of this study provided a significant theoretical framework for understanding the twinning behavior of high-performance and homogeneous l-PBF metallic materials.

中文翻译：

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热等静压均匀化激光粉末床熔融奥氏体钢的变形行为、孪晶倾向模型和孪晶能力图

热等静压 (HIP) 已成为一种高效且广泛采用的技术，用于消除激光粉末床熔融 (L-PBF) 金属材料的内在缺陷、减轻残余应力和解决微观结构各向异性。然而，热等静压 l-PBF 奥氏体钢的变形行为、强化机制和相关机制模型仍不清楚。通过多种微观结构表征，本研究确定 HIPed l-PBF 奥氏体钢的主要变形机制涉及从退火孪晶界或大角度晶界 (HAGB) 发射部分孪晶，并装饰有额外位错和棱柱状夹杂物。基于已确定的变形机制，建立了孪生倾向模型，揭示了孪生部分发射的临界角 () 范围为 25.64° 至 28.46°。建立了考虑晶体取向和应力状态（大小和方向）的模型，以指导孪生控制以获得所需的机械性能。最后，利用显微组织结果有效地证实了孪生模型和孪生能力图的准确性，同时通过微观缺陷和织构分析合理检验了孪生模型和孪生能力图的局限性。这项研究的结果为理解高性能均质 l-PBF 金属材料的孪晶行为提供了重要的理论框架。