Influence of the laser beam parameters in the laser assisted double wire welding with nontransferred arc process on the seam geometry of generatively manufactured structures

The “laser assisted double wire welding with nontransferred arc” utilizes an arc burning between two laterally fed wires combined with a laser beam source and beam guidance. By oscillating in the transverse direction, the necessary thermal energy is put locally in a targeted manner and results in a homogeneous temperature profile overall. This leads to the uniform melting of the substrate surface so that complete fusion is achieved over the cross section. The linear oscillation of the laser beam is characterized by a sinusoidal function whose extrema are located in the edge regions of the melt pool and, due to the low velocity, pulls the melt pool apart. In this work, the influence of laser parameters on the seam geometry of generatively manufactured structures is investigated. These include pendulum amplitude, defocusing, and laser beam position of a disk laser with a wavelength at 1030 nm. This enables the selective adjustment of the seam width and seam height, thus allowing to generate structures of 316L at application rates of up to 21 kg/h using 400 A current for the arc [A. Barroi, J. Hermsdorf, U. Prank, and S. Kaierle, “A novel approach for high deposition rate cladding with minimal dilution with an arc – laser process combination,” Phys. Proc. 41, 249–254 (2013)]. In order to illustrate the effect of the laser beam on the melt pool, the processes are visually and thermally documented with a thermos camera and 300 fps. Furthermore, the influence of preheating by laser radiation on the seam quality and geometry is shown. The topology and geometry of the individual seams are determined using a confocal microscope. Thus, a minimal irregular seam of approximately 10 mm beginning at a defocusing of −1 mm and a laser beam position of −3.5 mm in the melt pool is achieved.