Recovery of dislocation cell structures in 316L stainless steel manufactured by selective laser melting

Abstract

Understanding the recovery mechanism associated with the dislocation cell structure in 316L austenitic stainless steel produced by selective laser melting (SLM), as well as the role played by the accompanying segregation network, is crucial for tailoring the microstructures and mechanical properties of SLM-prepared components. In the present work, the evolution of the dislocation cells was investigated during isothermal annealing, and a recovery mechanism for the dislocation cell structure was proposed based on a combination of microstructural observations and recovery kinetics analysis. The results show that the high-density dislocations at the cell boundaries annihilate during prolonged annealing at 800 °C, resulting in the decomposition of the dislocation cells. The recovery kinetics analysis reveals that SLM-prepared 316L exhibits a lower recovery rate and requires significantly higher apparent activation energy during annealing compared to conventional 316L deformed by cold rolling. The segregation network plays an important role during the dislocation recovery process, which limits the dislocation reaction occurring within the cell boundaries at the early stage of recovery, impedes the dislocation motion after the decomposition of dislocation cells, and leads to a strong temperature dependence of recovery kinetics in SLM-prepared 316L.

Keywords

• Selective laser melting
• 316L stainless steel
• Recovery
• Dislocation cell structure
• Segregation network