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

Abstract

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.

Numerical Simulation of Preheating Temperature on Molten Pool Dynamics in Laser Deep-Penetration Welding

“…where u, v, and w are the velocity vectors of different coordinate axes directions in the mathematical model; ρ is the density, P is the pressure, H is the enthalpy, k is the thermal conductivity, and µ is the viscosity; S m , S x , S y , S z , and S H are the source terms of the governing equations. In this mathematical model, the welding base material was 6056 aluminum alloy, and its thermophysical parameters were obtained from the literature [17], as shown in Table 1.…”

Numerical Simulation of Droplet Filling Mode on Molten Pool and Keyhole during Double-Sided Laser Beam Welding of T-Joints

“…However, in the current literature on the numerical simulation of DSLBW of T-joints, filler metal was prefabricated on both sides of T-joints before welding, so the influence of welding wire on the weld pool was not considered. Yang et al [15][16][17] established the numerical model of DSLBW of T-joints. Assuming that the workpiece surface was a rigid surface, the relationship between the interconnectivity of two laser beams and the porosity of weld was studied.…”

Numerical and Experimental Investigations of Solidification Parameters and Mechanical Property during Laser Dissimilar Welding

“…The temperature field calculated by heat conduction equation and microstructure evolution during friction stir welding (FSW) of Al-Mg were investigated by Skeikh Ahmad et al [11]. The correlations of thermal characteristics and microhardness during LBW of AA 6165 and AA 6056 aluminum alloys were studied by Yang et al [12] using a three dimensional fluid flow model, but the effect of the solidification parameters on the microstructure was not considered. Therefore, it is urgent to study the influence of the solidification parameters on the final microstructure and the mechanical characteristics during dissimilar joints.…”