A parametric study of Inconel 625 wire laser deposition

Abstract

Laser deposition with wire offers saving potentials over powder based systems. These include a cleaner processing environment, reduced economic and environmental cost of producing the wire, better surface finish and higher material deposition rates. This technique is rapidly finding applications for the manufacture and repair of high value components. For the first time, the deposition of Inconel 625 wire for single tracks at varying processing parameters using a 2-kW Ytterbium doped fibre laser has been investigated. A process map predicting the process characteristics in terms of wire dripping, smooth wire transfer and wire stubbing at different cladding conditions has been developed. Track geometrical characteristics including aspect ratio and contact angle were evaluated using surface profilometry and optical microscopy. Scanning electron microscopy equipped with energy dispersive X-ray spectroscopy was used to determine the dilution ratio (%) of the tracks. Wire deposition volume per unit length of track and energy per unit length of track were found to be key parameters influencing both the process and track geometrical characteristics. Aspect ratio and dilution ratio showed positive dependency whereas contact angle showed negative dependency on energy per unit length of track. Conversely, material deposition volume per unit length of track varied directly with contact angle but inversely with aspect ratio and dilution ratio (ranging from 0% to 24%). Processing conditions at which a combination of favourable single track properties including low contact angle (<80°), minimal dilution ratio (5–13%) and high surface quality were achieved are presented. These properties are required for depositing overlapped tracks of good surface finish, minimal dilution and free of inter-run porosity.