The thermal stability of dislocation cellular structures in three additively manufactured (AM) austenitic stainless steels (SSs), 316L SS, 304L SS, and Al modified 316L SS (316L(Al)), were studied. Minor alloying elements, Mo and Al, were found affecting the stability of the cellular structures in AM austenitic SS, resulting in a stability ranking of AM 316L SS > AM 304L SS > AM 316L(Al) SS. As a result, their abilities towards recrystallization also differed. Owing to the high stacking fault energy (SFE) due to Al addition, AM 316L(Al) SS had the least stable subgrain cellular structure and exhibited the lowest recovery temperature. Although 316L SS possessed slightly higher SFE than 304L SS, the pinning effect due to Mo segregation at the cellular walls in AM 316L SS significantly enhanced its thermal stability. While the low-SFE AM 316L SS and AM 304L SS recovered their cellular structures via the equiaxed cell growth, the dislocation cellular walls in high-SFE AM 316L(Al) SS continuously vanished along a preferred direction. The fast recovery of cellular structures led to recrystallization retardation. The Hall–Petch model was found incapable of correlating cell size to strength because of the continuous weakening of cellular walls during heat treatment.

中文翻译：

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关于增材制造奥氏体不锈钢中位错胞结构的热稳定性：重元素偏析和堆垛层错能的作用

研究了三种增材制造 (AM) 奥氏体不锈钢 (SS)、316L SS、304L SS 和铝改性 316L SS (316L(Al)) 中位错蜂窝结构的热稳定性。发现微量合金元素 Mo 和 Al 会影响 AM 奥氏体 SS 中细胞结构的稳定性，导致稳定性等级为 AM 316L SS > AM 304L SS > AM 316L(Al) SS。因此，它们的再结晶能力也不同。由于 Al 添加导致的高堆垛层错能 (SFE)，AM 316L(Al) SS 具有最不稳定的亚晶胞结构和最低的恢复温度。尽管 316L SS 的 SFE 比 304L SS 略高，但由于在 AM 316L SS 的蜂窝壁上 Mo 偏析而产生的钉扎效应显着增强了其热稳定性。虽然低 SFE AM 316L SS 和 AM 304L SS 通过等轴细胞生长恢复了它们的细胞结构，但高 SFE AM 316L(Al) SS 中的位错细胞壁沿着首选方向不断消失。细胞结构的快速恢复导致再结晶延迟。由于热处理过程中细胞壁的持续弱化，Hall-Petch 模型无法将细胞大小与强度相关联。