Experimental Investigation and Numerical Modeling of Deep Penetration laser and GTA Welding Processes
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Date
2015
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Abstract
Fusion welding process is complex in nature since it involves several interactive physical phenomena. An accurate knowledge of weld induced distortions and residual stress. final micro structure and mechanical processes of weld joint are greatly influenced by thermal history.cooling rate and consequently the weld dimensions. Real-time measurement of the transient growth of temperature and material flow field during welding is extremely difficult and there is uncertainty to accurately measure the residual stress of weld joint.Alternatively, the computational model of increasing complexity based on scientific principle alone is an effective route to analyze the differential influence of process parameters during fusion welding process. The major difficulty of conduction heat transfer based modeling approach is a-prior definition of several heat source parameters which are limited by the definition of weld dimensions only from experimental measurement. The formation of keyhole in laser welding produces deep penetration weld joint whereas proper choice of surface active elements at optimum quantity promotes high penetration weld joint in gas tungsten arc(GTA) welding process. The mechanism of material flow by surface tension gradient prevails in GTA welding process. However, the interracial phenomena like evaporation, homogeneous boiling. and multiple reflections in laser welding brings the complexity in formation of keyhole moreover, the absorptivity of laser and weld joint quality is greatly affected by presence of shielding gas.
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Supervisor: Swarup Bag
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MECHANICAL ENGINEERING