Numerical modeling of heat transfer and fluid flow in hybrid laser–TIG welding of aluminum alloy AA6082

In order to investigate the effect of droplet impact on molten pool dynamics in hybrid laser-MIG (metal inert gas) welding, a three-dimensional mathematical model was developed, and a new approach to simulate the droplet impact was proposed. In the model, the droplet heat and impact under the influence of laser was considered, and the deformation of molten pool was calculated with considering droplet impact and arc pressure. To simplify the model, a modified body heat source model was presented for laser source to take into account multiple reflections and Fresnel absorption. Surface tension, electromagnetic force, and buoyancy were considered to calculate the fluid flow pattern. Furthermore, several dimensionless numbers were used to recognize the importance of the driving forces in molten pool. It was found that molten pool dynamics and final weld bead geometry were strongly affected by the droplet impact. To demonstrate the importance of droplet impact, the temperature, velocity distribution, and the deformation of molten pool were analyzed and compared under different conditions. With considering droplet impact, the penetration was bigger, and the width was smaller. Furthermore, the simulated weld bead geometry was in good agreement with experimental measurement.

Section: The Heat Source Modelmentioning

confidence: 99%

Effect of droplet impact on molten pool dynamics in hybrid laser-MIG welding of aluminum alloy

Chen

et al. 2018

“…These assumptions are often adopted in the previous related research [12][13][14][15]. Under the combination of laser energy, surface tension, thermal buoyancy, gravity and recoil pressure, complex flow phenomena was induced in the emerged weld molten pool.…”

Section: Numerical Modelmentioning

confidence: 99%

Numerical modelling and experimental verification of thermal characteristics and their correlations with mechanical properties of double-sided laser welded T-joint

Yang

Wang

Zhao³

et al. 2017

In this study, a three-dimensional model was developed to investigate the temperature fields during a doublesided laser welding process of T-joints, and the correlations between the thermal characteristics and the mechanical properties were researched in details. To verify the modelling results, welding experiments were conducted with two different welding parameters and the geometrical dimensions of the weld pool were measured. It was found that there was a good agreement between the calculated and the measured results. The calculated results showed that the temperature profile was bilateral symmetry along the stringer centre, and the temperature gradient became greater as running far from the stringer centre, especially on the skin side. All of the tensile specimens were fractured along the fusion line on the skin panels for the head and the hoop tensile tests. The loss of the alloying elements near the fusion line on the skin side resulted in the lowest micro-hardness value appeared here, and made it to be the weakest region of the welded T-joints. The calculated thermal cycles indicated that the materials closest to the fusion line on the skin side had been staying at higher temperature for a longer time, and which is the essential reason for the fracture behaviour, micro-hardness distribution and alloying elements distribution of the double-sided laser welded T-joint.

“…Tungsten inert-gas (TIG) is a high-quality welding method for aluminum alloy [6], but the welding efficiency is low because of an infusible tungsten. Several other methods, such as laser-arc hybrid welding [7][8][9] and friction stir welding [10,11], are also used in aluminum alloy. Nevertheless, the equipment cost of the laser-arc hybrid welding is high.…”

Section: Introductionmentioning

confidence: 99%

Effect of process parameters on tensile strength in plasma-MIG hybrid welding for 2219 aluminum alloy

Yang

Xiong

Chen

2015

2219 aluminum alloy is one of the most extensively used materials for the fabrication of rocket fuel storage box. This paper aims at revealing effect of process parameters on tensile strength in 2219 aluminum alloy welded by means of the plasma-MIG hybrid welding method. Process parameters such as MIG voltage, plasma gas, plasma current, welding speed, wire feed speed, etc. play a major role in deciding the joint tensile strength. An attempt has been made to establish an empirical relationship between process parameters and the tensile strength by applying a second-order regression model. A central composite design was applied to perform experiments for obtaining input-output data. The established model was tested for its adequacy and significance. Influences of single factor and interactive effect on tensile strength were analyzed. The maximum tensile strength of 2219 aluminum alloy jointed by plasma-MIG hybrid welding was 289.6 MPa.