Analysis of heat transfer and melt flow in conduction, transition, and keyhole modes for CW laser welding

2010 ◽

Cited By ~ 2

Author(s):

Jun Zhou ◽

Hai-Lung Tsai

Keyword(s):

Heat Transfer ◽

Laser Welding ◽

Welding Process ◽

Solidification Process ◽

Melt Flow ◽

Single Beam ◽

Keyhole Welding ◽

Beam Laser ◽

Dual Beam ◽

Laser Keyhole Welding

Dual-beam laser welding has become an emerging joining technique. Studies have demonstrated that it can provide benefits over conventional single-beam laser welding, such as increasing keyhole stability, slowing down cooling rate and delaying the humping onset to a higher welding speed. It is also reported to be able to improve weld quality significantly. However, due to its complexity the development of this promising technique has been limited to the trial-and-error procedure. In this study, mathematical models are developed to investigate the heat transfer, melt flow, and solidification process in three-dimensional dual-beam laser keyhole welding. Effects of key parameters, such as laser-beam configuration on melt flow, weld shape, and keyhole dynamics are studied. Some experimentally observed phenomena, such as the changes of the weld pool shape from oval to circle and from circle to oval during the welding process are analyzed in current study.

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Transport Phenomena and the Associated Humping Formation in Laser Welding

Heat Transfer, Part B ◽

10.1115/imece2005-81766 ◽

2005 ◽

Cited By ~ 1

Author(s):

J. Zhou ◽

H. L. Tsai ◽

P. C. Wang

Keyword(s):

Heat Transfer ◽

Liquid Metal ◽

Laser Welding ◽

High Speed ◽

Solidification Rate ◽

Transport Phenomena ◽

Metal Flow ◽

Welding Process ◽

Solidification Process ◽

Melt Flow

Humping is a frequently observed welding defect in laser welding which is caused when the welding speed exceeds a certain limit while the other welding conditions remain unchanged. Humping is characterized by the appearance of unsmooth and discontinuity of humps at the surface of the weld. The formation of humping is generally understood to be caused by the complex heat transfer and melt flow in a high speed welding process. However, so far the fundamental mechanisms causing humping are not fully understood, and research on determining the onset of humping has been based on the “trial-and-error” procedure. In this paper, mathematical models previously developed by the authors for the transport phenomena in laser welding have been extended to investigate the formation of the humping defect. In this study, the transient heat transfer and melt flow in the weld pool during the keyhole formation and collapse, and melt solidification are calculated for a 3-D moving laser welding. Different humping patterns have been predicted by the present study in different laser power levels and welding speeds. From the present study, it was found that the formation of humping in laser welding is caused by the interplay between two important factors: a) the strong liquid metal flow in the real part of the keyhole induced mainly by the laser recoil pressure and b) the rapid solidification rate of the liquid metal. The humping pattern can be well explained by the calculated melt flow and the solidification process.

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INVESTIGATION OF HUMPING FORMATION BASED ON MELT FLOW ANALYSIS IN HIGH-SPEED LASER WELDING PROCESS

ACTA METALLURGICA SINICA ◽

10.3724/sp.j.1037.2013.00058 ◽

2013 ◽

Vol 49 (6) ◽

pp. 725 ◽

Cited By ~ 3

Author(s):

Yinglei PEI ◽

Aiping WU ◽

Jiguo SHAN ◽

Jialie REN

Keyword(s):

Laser Welding ◽

High Speed ◽

Flow Analysis ◽

Welding Process ◽

Melt Flow ◽

Laser Welding Process

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Modelling of Thermal Quantities for Quick Process Assessment and Process Capability Space Refinement at an Early Design Phase During Laser Welding

10.21203/rs.3.rs-1129775/v1 ◽

2021 ◽

Author(s):

Anand Mohan ◽

Dariusz Ceglarek ◽

Michael Auinger

Keyword(s):

Heat Transfer ◽

Laser Welding ◽

Cooling Rate ◽

Process Parameters ◽

Thermal Cycle ◽

Welding Process ◽

Process Capability ◽

Peak Temperature ◽

Transfer Model ◽

Process Assessment

Abstract This research aims at understanding the impact of welding process parameters and beam oscillation on the weld thermal cycle during laser welding. A three-dimensional heat transfer model is developed to simulate the welding process, based on the finite element (FE) method. The calculated thermal cycle and weld morphology are in good agreement with experimental results from literature. By utilizing the developed heat transfer model, the effect of welding process parameters such as heat source power, welding speed, radius of oscillation, and frequency of oscillation on the intermediate performance indicators (IPIs) such as peak temperature, heat-affected zone volume (HAZ), and cooling rate is quantified. Parametric contour maps for peak temperature, HAZ volume, and cooling rate are developed for the estimation of the process capability space. An integrated approach for rapid process assessment, process capability space refinement, based on IPIs is proposed. The process capability space will guide the identification of the initial welding process parameters window and help in reducing the number of experiments required by refining the feasible region of process parameters based on the interactions with the IPIs. Here, the peak temperature indicates the mode of welding performed while the HAZ volume and cooling rate are weld quality indicators. The regression relationship between the welding process parameters and the IPIs is established for quick estimation of IPIs to replace time-consuming numerical simulations. The proposed approach provides a unique ability to simulate the laser welding process and provides a robust range of process parameters.

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Numerical and physical study of transitions to unsteady modes of melt flow with the Prandtl number 16 in the Czochralski method

Journal of Physics Conference Series ◽

10.1088/1742-6596/2119/1/012165 ◽

2021 ◽

Vol 2119 (1) ◽

pp. 012165

Author(s):

V S Berdnikov ◽

V A Vinokurov ◽

V V Vinokurov

Keyword(s):

Heat Transfer ◽

Prandtl Number ◽

Unsteady Flow ◽

Flow Structure ◽

Characteristic Temperature ◽

Temperature Drop ◽

Czochralski Method ◽

Melt Flow ◽

Flow And Heat Transfer ◽

Physical Study

Abstract The evolution of the flow structure and heat transfer with an increase in the characteristic temperature drop in the ranges of Grashof and Marangoni numbers 3558 ≤ Gr ≤ 7116 and 2970 ≤ Ma ≤ 5939 are investigated numerically. The boundary of the transition to unsteady flow and heat transfer regimes has been determined.

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Simulation of Multi-Phase Glass-Melt Flows in a Glass Melter

10.1115/imece2001/htd-24235 ◽

2001 ◽

Author(s):

S. L. Chang ◽

C. Q. Zhou ◽

B. Golchert ◽

M. Petrick

Keyword(s):

Heat Transfer ◽

Molten Glass ◽

Transfer Rate ◽

Liquid Glass ◽

Particle Number ◽

Particle Number Density ◽

Number Density ◽

Melt Flow ◽

Glass Melter ◽

Multi Phase

Abstract A typical glass furnace consists of a combustion space and a melter. The intense heat, generated from the combustion of fuel and air/oxygen in the combustion space, is transferred mainly by radiation to the melter where the melt sand and cullet (scrap glass) are melted, creating molten glass. The melter flow is a complex multi-phase flow including solid batches of sand/cullet and molten glass. Proper modeling of the flow patterns of the solid batch and liquid glass is a key to determining the glass quality and furnace efficiency. A multi-phase CFD code has been developed to simulate glass melter flow. It uses an Eulerian approach for both the solid batch and the liquid glass-melt flows. The mass, momentum, and energy conservation equations of the batch flow are used to solve for local batch particle number density, velocity, and temperature. In a similar manner, the conservation equations of mass, momentum, and energy of the glass-melt flow are used to solve for local liquid molten glass pressure, velocity, and temperature. The solid batch is melted on the top by the heat from the combustion space and from below by heat from the glass-melt flow. The heat transfer rate from the combustion space is calculated from a radiation model calculation while the heat transfer rate from the glass-melt flow to the solid batch is calculated from a model based on local particle number density and glass-melt temperature. Energy and mass are balanced between the batch and the glass-melt. Batch coverage is determined from local particle number density and velocity. A commercial-scale glass melter has been simulated at different operating/design conditions.

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