Comparison of CMT with other arc modes for laser arc hybrid welding of 7 mm steel

• In this study, three different arc modes in laser arc hybrid welding with a Gas Metal Arc (GMA) are studied, i.e. Standard, Pulsed and Cold Metal Transfer (CMT) mode. Originally developed for being able to weld thin materials, the pulsed mode is the favoured arc mode in both ordinary arc welding and laser hybrid welding. The pulsed mode is a more controlled GMA welding process that uses less heat and is able to weld thinner materials than the Standard mode process while utilizing globular drop flight transfer. The CMT mode utilizes surface tension drop transfer with controlled wire feeding and can thereby be used for much less heated welds compared to the other arc modes. It is also considered to generate less undercuts and spatter compared to the other modes, by both developers and users alike. This study compares hybrid welds made by the three arc modes for low and medium wire deposition rates, within the limits of the CMT process. The welds are studied by macrographs, scanning and high speed imaging. The study shows that the differences between the drop transfer modes are partially eliminated due to the presence of a laser keyhole. The dominating impact on the solidification and melt flow is the arc and especially the gouge created ahead of the keyhole. The main pros and cons to use either arc mode are discussed.

Ämnesord

TEKNIK OCH TEKNOLOGIER  -- Materialteknik -- Bearbetnings-, yt- och fogningsteknik (hsv//swe)

ENGINEERING AND TECHNOLOGY  -- Materials Engineering -- Manufacturing, Surface and Joining Technology (hsv//eng)

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Manufacturing Systems Engineering

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