Experimental study and simulation of sintering of 316L components produced by binder jetting
Licentiatavhandling, 2023
During BJT printing, the powder is being deposited layer-by-layer and binder is selectively placed to create a 3D geometry. Therefore, the metal particle’s arrangement of the green BJT components is influenced by the layer-by-layer buildup nature of the printing process. This impacts the behavior of the components during the debinding and sintering process. The first part of this study aims to develop the understanding of densification development during the sintering of 316L stainless-steel BJT samples. The intensity of the dimensional evolution anisotropy was characterized by multi-axial dilatometry experiments. Measured shrinkages were up to 15% higher along the building direction, while minor variation was found between the other two orthogonal directions. Only small shrinkages (<0.5%) were observed during debinding without significant anisotropy. A rapid increase of the shrinkage rate was observed at high temperature (~1310°C), related to the formation of δ-ferrite phase. This boost of densification is critical to achieve high densities (96-99%) of 316L BJT sintered components. The second part consists of the microstructural evolution analysis. The EBSD phase maps showed the formation of δ-ferrite at temperatures >1300°C. The porosity characterization within different cross-sections demonstrated that some anisotropic distribution of porosity may be developed during sintering.
The last part of this study introduces the application of the continuum theory of sintering for modelling the sintering behavior of 316L BJT components. The identification of model parameters was done from dilatometry data. Then, a new material viscosity expression was proposed to account for the effect of δ-ferrite transformation. The model was proved to accomplish good predictions of the density evolution during sintering of BJT samples.
binder jetting
316L stainless steel
additive manufacturing
dilatometry
sintering modelling
Sintering
anisotropy
Författare
Alberto Cabo Rios
Chalmers, Industri- och materialvetenskap, Material och tillverkning
Sintering anisotropy of binder jetted 316L stainless steel: part I–sintering anisotropy
Powder Metallurgy,;Vol. 65(2022)p. 273-282
Artikel i vetenskaplig tidskrift
Sintering anisotropy of binder jetted 316L stainless steel: part II–microstructure evolution during sintering
Powder Metallurgy,;Vol. 65(2022)p. 283-295
Artikel i vetenskaplig tidskrift
Modelling of δ-ferrite transformation effect on the sintering behaviour of 316L binder jetted components. Alberto Cabo Rios, Eugene A. Olevsky, Eduard Hryha, Mats Persson. WorldPM2022 Conference proceedings, 2022.
Ämneskategorier
Materialteknik
Annan materialteknik
Metallurgi och metalliska material
Styrkeområden
Materialvetenskap
Utgivare
Chalmers
Virtual Development Laboratory (VDL-room), Hörsalsvägen 7A, Chalmers University of Technology in Gothenburg, Sweden
Opponent: Dr. Dimitris Chasoglou Höganäs AB, Sweden