Numerical analysis of thermal fluid transport behavior during electron beam welding of 2219 aluminum alloy plate

A two-dimensional mathematical model based on volume-of-fluid method is proposed to investigate the heat transfer,fluidflow and keyhole dynamics during electron beam welding(EBW)on20mm-thick2219aluminum alloy plate.In the model,anadaptive heat source model tracking keyhole depth is employed to simulate the heating process of electron beam.Heat and masstransport of different vortexes induced by surface tension,thermo-capillary force,recoil pressure,hydrostatic pressure and thermalbuoyancy is coupled with keyhole evolution.A series of physical phenomena involving keyhole drilling,collapse,reopening,quasi-stability,backfilling and the coupled thermal field are analyzed systematically.The results indicate that the decreased heat fluxof beam in depth can decelerate the keyholing velocity of recoil pressure and promote the quasi-steady state.Before and close to thisstate,the keyhole collapses and complicates the fluid transport of vortexes.Finally,all simulation results are validated againstexperiments.

Numerical analysis of thermal fluid transportation during electron beam welding of 2219 aluminum alloy plate and experimental validation

A three-dimensional mathematical model using volume-of-fluid method is developed to investigate the heat transfer, fluid flow and keyhole dynamics during electron beam welding of 2219 aluminum alloy plate. In the model, an adaptive heat source is employed to simulate the heating process of electron beam. Fluid flow is mainly driven by surface tension, thermo-capillary force, recoil pressure, hydrostatic pressure and thermal buoyancy. The thermal-fluid transport behaviors of welding pool during the drilling and backfilling stages of keyhole and the formation reason of the nail-shaped weld with an arc crater are systematically analyzed. Finally, all calculation results are validated by experiments and show good agreements.

Investigation into keyhole-weld pool dynamic behaviors based on HDR vision sensing of real-time K-TIG welding process through a steel/glass sandwich

To obtain a deep insight into keyhole tungsten inert gas welding,it is necessary to observe the dynamic behavior of the weld pool and keyhole.In this study,based on the steel/glass sandwich and high dynamic range camera,a vision system is developed and the keyhole-weld pool profiles are captured during the real-time welding process.Then,to analyze the dynamic behavior of the weld pool and keyhole,an image processing algorithm is proposed to extract the compression depth of the weld pool and the geometric parameters of the keyhole from the captured images.After considering the variations of these parameters over time,it was found that the front and rear lengths of the keyhole were dynamically adjusted internally and had opposite trends according to the real-time welding status while the length of the keyhole was in a quasi-steady state.The proposed vision-based observation method lays a solid foundation for studying the weld forming process and improving keyhole tungsten inert gas welding.