The highly localized multiphysics nature of laser powder bed fusion (PBF-LB) induces complex transient temperature and strain profiles that challenge predictive modeling of microstructure evolution and resulting mechanical properties. Discrete dislocation dynamics (DDD) simulations were conducted to model the evolution of dislocation structures during rapid cooldown after laser powder bed fusion (PBF-LB) of 316L stainless steel. The DDD model incorporated the transient temperature profiles and stress evolution from finite element (FEM) thermomechanical simulations. Three cooling rate profiles were modeled. At lower cooling rates, higher overall dislocation densities and earlier emergence of organized dislocation cell structures oriented along [100] directions were observed. The accumulation of dislocations at solute-enriched cell walls increased progressively during cooling, independently of the cooling rate. Capturing this transient dislocation evolution provides insights into defect formation mechanisms and enables direct comparisons to experimental characterization. This will support microstructure-informed process optimization for tailored mechanical performance of additively manufactured alloys.

中文翻译：

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通过缺陷建模将加工条件与激光粉末床熔合中的微观结构演变联系起来

激光粉末床熔合 (PBF-LB) 的高度局部化多物理场性质会产生复杂的瞬态温度和应变分布，这对微观结构演化和由此产生的机械性能的预测建模提出了挑战。采用离散位错动力学 (DDD) 模拟来模拟 316L 不锈钢激光粉末床熔合 (PBF-LB) 后快速冷却过程中位错结构的演变。DDD 模型结合了有限元 (FEM) 热机械模拟的瞬态温度曲线和应力演化。对三种冷却速率曲线进行了建模。在较低的冷却速率下，观察到较高的总体位错密度和沿[100]方向定向的有组织位错单元结构的较早出现。在冷却过程中，富含溶质的细胞壁处的位错积累逐渐增加，与冷却速率无关。捕捉这种瞬态位错演化可以深入了解缺陷形成机制，并能够与实验表征进行直接比较。这将支持基于微观结构的工艺优化，以实现增材制造合金的定制机械性能。