The Complex reheating phenomenon during friction stir additive manufacturing (FSAM) has a significant impact on the microstructural evolution. This, in turn, affects its mechanical properties. A flow stress model including the precipitate, solid solution and dislocation density evolution was proposed to reveal the relationship between the microstructure and constitutive behavior in FSAM of Al-Mg-Si alloys. The microstructure and mechanical properties of single-layer and multi-layer FSAM were investigated using experimental and numerical simulation methods. The results revealed that during the first reheating process, the precipitates exhibited dissolution and coarsening behavior in the heating stage. In the third reheating process, precipitates were generated during the heating stage because of the lower temperature. The multiple reheating process in FSAM promoted the generation of precipitates in the stirring zone. This phenomenon increased the yield strength from 183.46 MPa to 189.95 MPa. Meanwhile, the precipitate nucleation and growth during reheating process depleted the concentrations of Si and Mg in the matrix. A comparison of the stress-strain curves before and after the reheating process, revealed that the reheating process reduces the net flow stress in the plastic deformation stage. A decrease in the concentration of solid solution elements caused a decrease in the statistically stored dislocation density, and thereby, decreased the net flow stress.

中文翻译：

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基于微观结构的搅拌摩擦增材制造本构行为仿真


搅拌摩擦增材制造 （FSAM） 过程中的复杂再加热现象对微观结构演变有重大影响。这反过来又会影响其机械性能。提出了一个包括沉淀、固溶体和位错密度演变的流动应力模型，以揭示 Al-Mg-Si 合金 FSAM 的微观组织和本构行为之间的关系。采用实验和数值模拟方法研究了单层和多层 FSAM 的微观结构和力学性能。结果表明，在第一次再加热过程中，沉淀物在加热阶段表现出溶解和粗化行为。在第三次再加热过程中，由于温度较低，在加热阶段会产生沉淀物。FSAM 中的多次再加热过程促进了搅拌区沉淀物的产生。这种现象使屈服强度从 183.46 MPa 增加到 189.95 MPa。同时，再加热过程中沉淀物的成核和生长耗尽了基体中 Si 和 Mg 的浓度。对再加热过程前后的应力-应变曲线的比较表明，再加热过程降低了塑性变形阶段的净流应力。固溶体元素浓度的降低导致统计存储的位错密度降低，从而降低了净流动应力。