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

The keyhole welding process in Variable Polarity Plasma Arc Welding enhances weld quality significantly, yet it introduces pool instability. Dynamic stability is pursued by investigating molten metal flowing within keyholes and their characteristics. Weld pool flow patterns are obtained via particle tracking, while instability characteristics are captured employing a high-speed camera. Analysing directional molten metal flow unveils Convergence and Separation Points in weld pool flow. The latter's displacement induces weld pool instability, resulting in an increase in keyhole area and a reduction in the pinch angle. The keyhole area signifies pool instability, while the rear wall angle reflects the welding state. These findings provide a theoretical basis for weld control and advance vision-based intelligent manufacturing welding techniques.

Section: Introductionmentioning

confidence: 99%

The characteristics of dynamic stability in aluminium alloy keyhole weld pool flow

Liu,

Jiang,

Chen

et al. 2023

“…Based on the results of the aforementioned process experiments, some researchers utilised process monitoring information to investigate the dynamic evolution of keyholes and molten pools in LBOW, which are used for validation in finite element analysis [10], or to explain the weld performance such as Yan et al [11] studied the flow velocity trend of the molten pool in the LBOW process of IN-718 alloy using high-speed imaging and found that the fluid flow velocity was highest at a oscillation frequency of 150 Hz, resulting in more effective scouring of dendrites. These studies often showcase individual images with distinctive features, and the sensors used are typically limited and have low sampling frequencies, which cannot provide a comprehensive characterisation of the welding process.…”

Section: Introductionmentioning

confidence: 99%

Investigation of keyhole behaviour and its impact on the performance of laser beam oscillating welding through imaging and acoustic signal analysis

Zhang,

Chen,

Tan

et al. 2023

Self Cite

As an emerging laser welding optimisation technique, beam oscillation still lacks detailed investigation into its underlying process mechanisms. This study investigates the microstructure and mechanical properties of 316LN welded joints under four oscillation modes, the results demonstrate that beam oscillation can suppress columnar grain growth and reduce porosity defects, thereby enhancing weld formation and mechanical properties. Building upon these findings, visual and acoustic sensing techniques are employed to analyse dynamic features of keyholes and energy distribution. The correlation between keyhole geometric features and porosity propensity across different oscillation modes is elucidated through visual information. Additionally, the time and frequency domain features of the acoustic signals effectively characterise the stability of the welding process and laser energy absorption efficiency.

Effect of laser oscillation mode on LWAM deposition morphology and melting pool fluctuation

Yan,

Han,

Wang

et al. 2024

To investigate the impact of laser beam oscillation on melting pool fluctuation and deposition morphology during laser wire additive manufacturing, we observed transient melting pool fluctuations and measured the 3D deposition morphology. The study revealed that periodic beam oscillation enhances solution stirring, resulting in pronounced fluctuations in the melting pool and reduced roughness of the deposited surface. Furthermore, it was found that different laser oscillation modes resulted in different deposition morphologies. The shape of the melting pool is influenced by energy distribution characteristics, while the movement path of the spot determines this distribution. Moreover, the addition of beam oscillations effectively disperses the energy of the laser heat source, thereby mitigating the protrusion of the molten pool bottom.