Abstract In this work, AISI 316L steel produced through selective laser melting (SLMed 316L) was successfully modified through friction stir processing (FSP) technology. The microstructure, microhardness, nano-hardness and tensile properties of SLMed 316L were studied and the results were discussed. The effects of microstructure evolution, including grain size, grain orientation and dislocations, on both macroscopic and microscopic mechanical behavior of the material were examined. The relationship between grain orientation and nano-hardness was corrected for the Berkovich nanoindenter. It was demonstrated that FSP could effectively eliminate the holes and cracks of SLMed 316L, leading to refined, homogenous and dense microstructure. During FSP, SLMed 316L sustained both continuous and discontinuous dynamic recrystallization. Subsequently to FSP, the grain size was refined from 6.6 to 0.9 μm, total dislocation density decreased from 2.43 × 1015 to 1.04 × 1015 m−2, while geometrically necessary dislocation density increased from 2.16 × 1014 to 8.25 × 1014 m−2. The average microhardness and nano-hardness increased from 272 to 218 HV and 3.61 to 4.18 GPa, respectively. The yield and tensile strengths increased by 29% and 18%, respectively, while elongation was maintained. The main factors affecting the strength of SLMed 316L was grain size, followed by grain orientation and dislocation density.

中文翻译：

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激光选区熔化搅拌摩擦加工AISI 316L钢显微组织与力学性能的关系

摘要 在这项工作中，通过搅拌摩擦加工 (FSP) 技术成功地对选区激光熔化生产的 AISI 316L 钢 (SLMed 316L) 进行了改性。研究了SLMed 316L的显微组织、显微硬度、纳米硬度和拉伸性能，并对结果进行了讨论。研究了微观结构演化对材料宏观和微观力学行为的影响，包括晶粒尺寸、晶粒取向和位错。Berkovich 纳米压痕仪修正了晶粒取向和纳米硬度之间的关系。结果表明，FSP 可以有效消除 SLMed 316L 的孔洞和裂纹，导致微观结构细化、均匀和致密。在 FSP 期间，SLMed 316L 持续和不连续动态再结晶。随后到FSP，晶粒尺寸从 6.6 μm 细化到 0.9 μm，总位错密度从 2.43 × 1015 降低到 1.04 × 1015 m-2，而几何必要位错密度从 2.16 × 1014 增加到 8.25 × 1014 m-2。平均显微硬度和纳米硬度分别从 272 增加到 218 HV 和 3.61 到 4.18 GPa。屈服强度和抗拉强度分别增加了 29% 和 18%，而伸长率保持不变。影响SLMed 316L强度的主要因素是晶粒尺寸，其次是晶粒取向和位错密度。分别为 18 GPa。屈服强度和抗拉强度分别增加了 29% 和 18%，而伸长率保持不变。影响SLMed 316L强度的主要因素是晶粒尺寸，其次是晶粒取向和位错密度。分别为 18 GPa。屈服强度和抗拉强度分别增加了 29% 和 18%，而伸长率保持不变。影响SLMed 316L强度的主要因素是晶粒尺寸，其次是晶粒取向和位错密度。