Abstract
Abstract
This study establishes and experimentally validates a process window for controlling bead geometry in ER70S-6 directed energy deposition using arc (DED-Arc). A total of 170 single-bead deposits were produced across five voltage levels, eleven wire feed rate (WFR) levels, and five process speed (PS) levels. The experiments followed a full-factorial design, and the influence of each process variable was examined by comparing experiments in which the remaining conditions were held fixed. The limits of stable deposition were defined using rejection criteria, including a contact angle greater than 90°, visible spatter, defects, and irregular bead profiles. These features were assessed by visual inspection and optical microscopy. Within the stable processing range, the effects of PS, WFR, current, and voltage on bead width, height, depth of penetration, and contact angle were evaluated under fixed combinations of the remaining parameters. The speed ratio (SR = WFR/PS) was found to provide an accurate description of single bead geometry. Energy input was estimated using Q=(V×I × η)/v, assuming a GMAW thermal efficiency of η = 0.85. The resulting geometry heat-input relationships were plotted against bead morphologies, indicating that a single heat-input correlation does not adequately describe bead geometry. Selected conditions within the stable process window were subsequently examined through five-layer deposition trials confirming the repeatability of the chosen parameter combinations. This study clarifies how the main process parameters influence bead geometry and provides a basis for selecting conditions to control bead dimensions during deposition. The resulting process framework supports the development of DED-Arc procedures for structural applications in related sectors.