Energy Distribution and Effects on Weld and Defect Formation during Beam Oscillation Laser Welding
Energy Distribution and Effects on Weld and Defect Formation during Beam Oscillation Laser Welding
Monday, September 30, 2024: 3:40 PM
22 (Huntington Convention Center)
Rapid beam oscillation represents a promising technique for controlling process conditions and defects in laser welding of important alloy systems. With the introduction of circular beam oscillations, the energy distribution can be altered, leading to variations in weld dimensions, microstructure, and defect formation. However, the effect of beam oscillation on the weld and defect formation during high power laser welding of nickel alloys is still largely undocumented. During high power laser welding of Inconel 740H, horizontal solidification cracks form at locations between approximately 70 to 80% of the weld depth where the strain rate and stress simultaneously reach critical levels. By coupling three-dimensional heat transfer, fluid flow, and stress modeling tools, the role that the integration of circular beam oscillation plays in the formation of the strain rates and stresses driving this cracking phenomenon was identified. While the addition of a circular oscillation pattern appeared to lower the stress levels calculated along the solidification front, it did little to eliminate the appearance of horizontal cracking for most oscillation conditions. Only when the beam amplitudes reached levels on the order of 1.6 mm did the combination of strain rate and stress not reach critical levels and solidification cracking disappeared. Under these conditions, however, the weld depths were also significantly reduced.