Macroporosity free aluminum alloy weldments through numerical simulation of keyhole mode laser welding

Zhao, Hailiang; DebRoy, T.

doi:10.1063/1.1573732

Cited by 108 publications

(89 citation statements)

References 33 publications

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“…[2][3][4][5][6][7][8][9] These computationally efficient models ignored fluid flow, but found applications for the welding of high thermal conductivity alloys, such as aluminum alloys, where conduction is the main mechanism of heat transfer. However, these models cannot be applied to relatively low thermal conductivity alloys such as steel, because convection is usually the dominant mechanism of heat transfer.…”

Section: Introductionmentioning

confidence: 99%

A Convective Heat-Transfer Model for Partial and Full Penetration Keyhole Mode Laser Welding of a Structural Steel

Naresh

Kelly

Martukanitz

et al. 2007

Metall Mater Trans A

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In the keyhole mode laser welding of many important engineering alloys such as structural steels, convective heat transport in the weld pool significantly affects temperature fields, cooling rates, and solidification characteristics of welds. Here we present a comprehensive model for understanding these important weld parameters by combining an efficient keyhole model with convective three-dimensional (3-D) heat-transfer calculations in the weld pool for both partial and full penetration laser welds. A modified turbulence model based on PrandtlÕs mixing length hypotheses is included to account for the enhanced heat and mass transfer due to turbulence in the weld pool by calculating spatially variable effective values of viscosity and thermal conductivity. The model has been applied to understand experimental results of both partial and full penetration welds of A131 structural steel for a wide range of welding speeds and input laser powers. The experimentally determined shapes of the partial and full penetration keyhole mode laser welds, the temperature profiles, and the solidification profiles are examined using computed results from the model. Convective heat transfer was the main mechanism of heat transfer in the weld pool and affected the weld pool geometry for A131 steel. Calculation of solidification parameters at the trailing edge of the weld pool showed nonplanar solidification with a tendency to become more dendritic with increase in laser power. Free surface calculation showed formation of a hump at the bottom surface of the full penetration weld. The weld microstructure becomes coarser as the heat input per unit length is increased, by either increasing laser power or decreasing welding velocity.

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Section: Introductionmentioning

confidence: 99%

A Convective Heat-Transfer Model for Partial and Full Penetration Keyhole Mode Laser Welding of a Structural Steel

Naresh

Kelly

Martukanitz

et al. 2007

Metall Mater Trans A

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“…Consequently our understanding of the threshold temperature is not at all conclusive. Concerning a deep keyhole welding, for example, not a few studies have assumed that the keyhole surface temperature is equal to T v [8][9][10][11][12][13], implying that this is the minimal temperature in order to carry out the keyhole welding process. In the well-known paper by Semak and Matsunawa [2], however, this assumption was denied.…”

Section: Introductionmentioning

confidence: 99%

Experimental determination of temperature threshold for melt surface deformation during laser interaction on iron at atmospheric pressure

Hirano¹,

Fabbro²,

Muller³

2011

J. Phys. D: Appl. Phys.

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is an open access repository that collects the work of Arts et Métiers ParisTech researchers and makes it freely available over the web where possible. . It is thus essential to estimate the recoil pressure in order to describe physical processes or to carry out numerical simulations. However, there exists no quantitative estimation of the recoil pressure near the boiling temperature (T v ), which is particularly important in welding process. In this study we experimentally investigated the recoil pressure of pure iron around T v . The main interest was to determine the threshold surface temperature to start deformation of melt surface. Using camera-based temperature measurement with accurate evaluation of emissivity from experiment, it was shown that the surface temperature has to reach T v to initiate the melt surface deformation. This result provides the first experimental evidence for the frequently used assumption that a deep keyhole welding requires surface temperature over T v . It is indicated also that, in normal gas-assisted laser cutting process, the recoil pressure hardly contributes to material ejection when the surface temperature is lower than T v , as opposed to commonly believed presumption.

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“…The laser density attenuation along the workpiece thickness direction obeyed the Bouguer-Lambert law and can be expressed as [16]:…”

Section: Heat Source 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

Int J Adv Manuf Technol

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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.

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Macroporosity free aluminum alloy weldments through numerical simulation of keyhole mode laser welding

Cited by 108 publications

References 33 publications

A Convective Heat-Transfer Model for Partial and Full Penetration Keyhole Mode Laser Welding of a Structural Steel

A Convective Heat-Transfer Model for Partial and Full Penetration Keyhole Mode Laser Welding of a Structural Steel

Experimental determination of temperature threshold for melt surface deformation during laser interaction on iron at atmospheric pressure

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

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