Comparison of wire-arc and powder-laser additive manufacturing for IN718 superalloy: unified consideration for selecting process parameters based on volumetric energy density

Abstract

Wire-arc additive manufacturing (WAAM) as well as powder-laser additive manufacturing (PLAM) are both promising cladding additive manufacturing (AM) techniques for fabricating large IN718 superalloy parts. Correct selection of initial process parameters is an important prerequisite to ensure the success of subsequent AM stage and its dynamic adjustment. For comparing the relationship between the process parameters and their influence on the quality of WAAM and PLAM cladding beads, the relationship between the energy density and the most controllable parameters was comparatively studied from the perspective of unified energy dissipation and the weldability. The equal effective volumetric energy density can be obtained under different combinations of WAAM and PLAM parameters. The defects such as porosity formation, centerline grain boundary, and liquation cracking are mainly affected by the cladding speed, rather than the effective volumetric energy density. During WAAM and PLAM, the corresponding effective volumetric energy density range which can avoid internal and external defects is in the theoretical weldable zone of IN718 superalloy. The key to obtain a defect-free cladding bead is to properly control the energy input and its distribution. The high material utilization under equal effective power and cladding speed is the main reason why WAAM is more efficient than PLAM. According to the energy dissipation hypothesis and related formulas, different energy beam-based AM processes can be further compared under the equal energy input, which provides a basis for the selection of initial process parameters and the dynamic adjustment of main parameters.