Effect of the build angle applied in Inconel 718 alloy fabricated by laser powder bed fusion on the strengthening mechanisms of the micro-blasting process

초록

Micro-blasting is an excellent post-processing technique applied for enhancing the surface quality and mechanical properties of alloy parts fabricated by laser powder bed fusion (LPBF). However, two critical issues remain unresolved: the influence of initial surface morphology and the fundamental mechanisms responsible for the material property enhancements induced by micro-blasting of LPBF-manufactured superalloy parts are not yet fully understood. To address these gaps, the study systematically examines the characteristics of micro-blasted Inconel 718 alloy specimens produced by LPBF with build angles ranging from 30° to 55°. After micro-blasting, the material removal rate (MRR) and surface roughness are measured quantitatively, the surface topographies and internal microstructures are analyzed, and mechanical properties are tested under tensile loading conditions. The results observed after micro-blasting demonstrate that the MRR decreases with increasing build angle, and the tensile strength and elongation at failure increase, while the fracture behavior transforms from brittle to ductile. Furthermore, variations in the quantitative features of X-ray diffraction clearly demonstrate that the surface-strengthening mechanism of micro-blasting depends strongly on the build angle, where severe wear occurs on the surfaces of specimens fabricated with build angles less than 45° owing to the removal of surface asperities and valleys, while deformation caused by the concentration of internal compressive stress is the main strengthening mechanism in specimens fabricated with a build angles greater than 45°.

키워드