Sinusoidal oscillating laser welding of 7075 aluminum alloy: Hydrodynamics, porosity formation and optimization

An oscillation laser beam was conducted to enhance the mechanical property of Inconel 718 joints. The dynamic behaviours of molten pool on the microstructure and mechanical property of joints were investigated. The results showed that the improvement of Laves phase and the tensile property depended on the flow and thermal behaviours of molten pool. Compared with conventional laser welding, the maximum flow velocity on the surface of molten pool increased by 375.5%(150 Hz), which indicated the dendrites received greater bending stress to break more easily, resulting in the homogenisation of element. In addition, the oscillation laser beam decreased the temperature gradient from 218.5°C/mm to 73°C/mm, and the cooling rate of 150 Hz in the centre and edge of molten pool increased by 64.4% and 111.9%, which hindered the segregation phenomenon during the element diffusion to restrain the formation of Laves phase in the eutectic reaction.

Section: Discussionmentioning

confidence: 99%

Combined effect and mechanism of thermal behaviour and flow characteristic on microstructure and mechanical property of oscillation laser-welded of IN718

Yan

Meng

Chen

et al. 2023

“…The numerical study is based on our previously developed laser welding model [12][13][14][15] which is described by the solutions of mass, momentum, and energy conservation equations [16]. The difference within this study lies in the definition of the laser heat distribution from the volumetric and hybrid heat sources.…”

Section: Numerical Modelmentioning

confidence: 99%

Numerical study of beam oscillation and its effect on the solidification parameters and grain morphology in remote laser welding of high-strength aluminium alloys

Mohan

Ceglarek

Franciosa

et al. 2023

This study investigated the effect of beam oscillation on the solidification behaviour during laser welding of Al-5754 to Al-6061 alloy. In this study, a finite element model has been developed to simulate temperature and fluid flow fields by implementing different combinations of volumetric heat source models. Solidification parameters such as temperature gradient (G), solidification rate (R), cooling rate (G × R) and G/R are evaluated to understand the mechanism of microstructure formation. It was found that beam oscillation improves the tensile strength by 21.4% for full penetration welding due to an increase in the percentage of formation of equiaxed grains. Modelling results revealed that the cooling rate increases with an increase in oscillation frequency. However, tensile strength followed a parabolic distribution with a peak at the oscillation frequency of 300 Hz.

“…Rather than use simple linear motion for the beam in the case of conventional laser welding, a wobble mechanism can move the spot in different repeating patterns hundreds of times per second. The beam irradiates a larger area while maintaining a high energy density, and thus allows greater assembly tolerance [16, 17]. As noted by Rubben et al [10], who first developed wobble laser beam welding, it was claimed that it could increase the gap tolerance of tailor welded blanks to 25% of the sheet thickness.…”

Section: Introductionmentioning

confidence: 99%

Effect of beam wobbling on microstructure and hardness during laser welding of X70 pipeline steel

Yang

Chen

Huda

et al. 2022

Laser welding with beam wobbling was employed to weld X70 pipeline steel. The influence of beam wobbling on weld surface morphology, fusion zone microstructure, and microhardness was investigated. The formation of spatter was suppressed by beam wobbling using a beam with higher energy density. At a welding speed of 1.0 m min −1 , the weld metal produced with a circular laser wobble pattern contained more martensite but less ferrite, compared to that of static spot welded joint. The presence of more martensite led to the increase in fusion zone hardness. A softened region was found in the inter-critical heat-affected zone. The hardness of the softened region could be improved by increasing the welding speed (from 1.0 to 1.5 m min −1 ).