On the Strength of a 316L-Type Austenitic Stainless Steel Produced by Selective Laser Melting

The developed microstructure and the tensile behavior of a 316L-type steel produced by selective laser melting were studied. This paper particularly aims to clarify the dislocation substructures in the developed steel, focusing on the density of dislocations, their arrangement in cells/subgrains, related internal distortions, and specific strengthening. The experimental samples were obtained using a 3D selective laser melting system ProX200 (laser power of 240W, beam speed of 1070 mm/s, distance between tracks of 80 mu m, and layer thickness of 30 mu m) in a nitrogen atmosphere. The steel microstructure was characterized by a grain size of 20 mu m and a high dislocation density of 5 x 10(14) m(-2) in the grain/subgrain interiors. The rather strong fiber texture of <012> along the building direction resulted in different Taylor factors of 2.89 and 3.30 for tension along the building direction and the side direction, respectively. The yield strength of 645 +/- 5 MPa, the ultimate tensile strength of 750 +/- 10 MPa, and an elongation of 40 +/- 5% were obtained with a tensile test along the side direction. The rough calculation of the strengthening mechanisms suggested that the solid solution strengthening of 273 MPa and the dislocation strengthening of 262 MPa were the main contributors to the yield strength. Such a combination of strengthening from solid solution and homogeneously distributed numerous dislocations provides the processed steel with sufficient strengthening ability, leading to an outstanding strength-ductility combination.

Automated summary

This study investigates the developed microstructure and tensile behavior of a 316L-type steel produced by selective laser melting. It focuses on the density and arrangement of dislocations, internal distortions, and specific strengthening mechanisms in the steel. The experimental samples were obtained using a 3D selective laser melting system with specific parameters. The results show that the steel has a grain size of 20 μm, a high dislocation density, and a strong fiber texture. The tensile test reveals high yield strength, ultimate tensile strength, and elongation along the side direction. The strengthening mechanisms of solid solution and dislocations contribute to the outstanding strength-ductility combination of the processed steel.