The thermal evolution of nanoscale oxide inclusions in 316L stainless steel (SS) manufactured by laser powder bed fusion additive manufacturing (AM) was explored. The size, chemical composition, morphology, and distribution of the oxides were characterized as the function of heat treatment conditions. The study revealed the mechanistic driving force of the rapid oxide coarsening during recrystallization. Ostwald ripening governs oxide coarsening. The active grain boundary-oxide interaction at the early stage of recrystallization accelerated oxide coarsening via enhanced solute diffusion along grain boundaries. Pipe diffusion along dislocation cellular boundaries has a negligible contribution to oxide coarsening. At high temperatures (T > 1065 $°C$), although lattice diffusion primarily controlled the oxide growth, the contribution from the grain-boundary diffusion was necessary. The transformation from MnSiO₃ to CrMn₂O₄ took place in the un-recrystallized grains but was not observed when recrystallization started. The interaction of grain boundary and oxides during recrystallization resulted in a high fraction of oxides accumulated at grain boundaries. While oxide coarsening does not significantly alter the toughness value, grain-boundary oxides promote microvoid formation and intergranular fracture under Charpy impact in the recrystallized AM 316L SS.

探讨了激光粉末床熔融增材制造 (AM) 制造的 316L 不锈钢 (SS) 中纳米级氧化物夹杂物的热演化。氧化物的尺寸、化学成分、形态和分布被表征为热处理条件的函数。该研究揭示了再结晶过程中氧化物快速粗化的机制驱动力。奥斯特瓦尔德熟化控制氧化物粗化。再结晶早期活跃的晶界-氧化物相互作用通过促进沿晶界的溶质扩散加速了氧化物的粗化。沿位错单元边界的管道扩散对氧化物粗化的贡献可以忽略不计。在高温下（T > 1065$°C$），虽然晶格扩散主要控制氧化物的生长，但晶界扩散的贡献是必要的。从MnSiO ₃到CrMn ₂ O ₄的转变发生在未再结晶晶粒中，但在再结晶开始时没有观察到。再结晶过程中晶界和氧化物的相互作用导致高比例的氧化物聚集在晶界处。虽然氧化物粗化不会显着改变韧性值，但晶界氧化物会在重结晶 AM 316L SS 的夏比冲击下促进微孔形成和沿晶断裂。