Abstract
The development of the laser powder bed fusion (L-PBF) process to increase its robustness and productivity is challenged by ambitious design optimizations, such as thin wall structures. In this study, in addition to the effect of commonly used gases as Ar and N2, increased laser scanning speed and new process gases, such as helium, were successfully implemented. This implementation allowed to build 316L stainless steel components with thin walls of 1 mm thickness with an enhanced build rate of 37 pct. The sample size effect and the surface roughness were held responsible for the reduction in strength (YS > 430 MPa) and elongation (EAB > 30 pct) for the 1 mm samples studied. Similar strength was achieved for all process gases. The increased scanning speed was accompanied by a more random texture, smaller cell size, and grain size factor along the building direction when compared to the material built with the standard laser parameters. Stronger preferential orientation 〈101〉 along the building direction was observed for material built with standard parameters. Finally, the use of helium as a process gas was successful and resulted in reduced cell size. This finding is promising for the future development of high strength 316L stainless steel built with high build rates.
Highlights
LASER-POWDER bed fusion (L-PBF) uses the energy from a laser to locally melt and solidify a bed of metallic powder
While the demand for new materials is constantly increasing to satisfy a broad range of applications, some materials offering good processability and high mechanical performances are well-established as 316L stainless steel
Regardless of the process atmosphere, the 1 mm samples picked up more oxygen than the 3 mm samples, see Table I
Summary
LASER-POWDER bed fusion (L-PBF) uses the energy from a laser to locally melt and solidify a bed of metallic powder. Applying layers of powder and exposing them to radiation in a controlled manner allows one to build 3D parts of relatively high complexity and resolution at rather low cost. This ability explains L-PBF’s broad adoption by various industries, such as aerospace, automotive, and medicine. While the demand for new materials is constantly increasing to satisfy a broad range of applications, some materials offering good processability and high mechanical performances are well-established as 316L stainless steel. Flowing from one side to another over the build plate, covering the process area, the gas applies a drag force on Manuscript submitted February 3, 2020.
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