NDLI: Transport Phenomena and the Associated Humping Formation in Laser Welding

Content Provider	The American Society of Mechanical Engineers (ASME) Digital Collection
Author	Zhou, J. Tsai, H. L. Wang, P. C.
Copyright Year	2005
Abstract	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.
Sponsorship	Heat Transfer Division
Starting Page	945
Ending Page	953
Page Count	9
File Format	PDF
ISBN	0791842223
DOI	10.1115/IMECE2005-81766
e-ISBN	0791837696
Volume Number	Heat Transfer, Part B
Conference Proceedings	ASME 2005 International Mechanical Engineering Congress and Exposition
Language	English
Publisher Date	2005-11-05
Publisher Place	Orlando, Florida, USA
Access Restriction	Subscribed
Subject Keyword	Collapse Errors Transport phenomena Welding Lasers Liquid metals Transient heat transfer Laser welding Flow (dynamics) Pressure Heat transfer Solidification
Content Type	Text
Resource Type	Article

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