Microstructural evolution and properties of 2 mm-thick thin-walled LPBF 316L stainless steel after solution treatment

Vollständiger Abstract

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Abstract The microstructure, mechanical properties, and corrosion behavior of 2 mm-thick thin-walled laser powder bed fusion (LPBF) 316L stainless steel plates after solution treatment were investigated. Here, ‘thin-walled’ refers to plate-like specimens with dimensions of 50 mm × 50 mm × 2 mm, corresponding to a width-to-thickness ratio of 25:1. Increasing solution-treatment temperature promoted melt-pool dissolution, recrystallization, and grain growth, leading to decreases in hardness from 250.7 HV to 226.9 HV and yield strength from 466.9 MPa to 407.4 MPa, while elongation increased to a maximum of 68.5%. The optimal strength–ductility balance was achieved at 1000 °C/30 min, with the highest strength–ductility product of approximately 40 691 MPa·%. Corrosion resistance improved at intermediate temperatures due to microstructural homogenization and enhanced passive-film stability, but deteriorated at higher temperatures because coarsened Si-rich oxide/complex inclusions introduced local chemical and electrochemical heterogeneity, thereby facilitating localized passive-film breakdown. These results provide insight into the solution-treatment response of a representative 2 mm-thick thin-walled LPBF 316l geometry and offer guidance for geometry-sensitive post-processing optimization.