Effect of Welding Speed on Melt Flow Behavior in High Speed Laser Welding Process

Laser welding process has been widely used in industrial manufacturing. The purpose of this paper is to explore the inter-relation between laser welding results and the laser-induced plume behavior. High-power disk laser welding of stainless steel type304 was performed at different welding speeds. Combing the high speed camera and ultraviolet sensing filter, the plume image sequences of laser welding process have been obtained. Plume features including plume volume and plume flowing direction have been extracted by using high-speed photography and image processing technology. The dynamic behavior of laser-induced plume was investigated. The results showed that the laser-induced plume feature, especially the plume volume, was closely related to laser welding process conditions.

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Monitoring of high-speed laser welding process based on vapor plume

Optics & Laser Technology ◽

10.1016/j.optlastec.2021.107649 ◽

2022 ◽

Vol 147 ◽

pp. 107649

Author(s):

Boce Xue ◽

Baohua Chang ◽

Dong Du

Keyword(s):

Laser Welding ◽

High Speed ◽

Welding Process ◽

Vapor Plume ◽

Laser Welding Process

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Extraction of Weld Pool Width Feature Based on Visual Sensing during High-Power Fiber Laser Welding

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.201-202.388 ◽

2012 ◽

Vol 201-202 ◽

pp. 388-391

Author(s):

Zi Qin Chen ◽

Xiang Dong Gao

Keyword(s):

Laser Welding ◽

Fiber Laser ◽

Weld Pool ◽

High Power ◽

High Speed ◽

Welding Process ◽

304 Stainless Steel ◽

Fiber Laser Welding ◽

Weld Pool Width ◽

Laser Welding Process

In a high-power fiber laser welding process, the thermal radiation of a weld pool contains plenty of information for welding quality, in which the pool width can reflect the welding stability. Thus, extracting the welding pool width of high-power fiber laser welding based on infrared thermal imaging is an important method for monitoring the weld seam quality. In this paper, we studied the 304 stainless steel welded by a 10kW high-power fiber laser continuously. A near-infrared high-speed sensing camera was used to capture the weld pool images. Image algorithms such as median filtering, gray scale stretching, cutting, dynamic threshold mathematical morphology were applied to extract the weld pool image edge, analyze and detect the weld pool width. Welding experimental results showed that the proposed methods could extract the weld pool width, which could reflect the stability status of high-power fiber laser welding process accurately.

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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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High-Speed X-Ray Transmission and Numerical Study of Melt Flows inside the Molten Pool during Laser Welding of Aluminum Alloy

Mathematical Problems in Engineering ◽

10.1155/2016/1409872 ◽

2016 ◽

Vol 2016 ◽

pp. 1-13 ◽

Cited By ~ 2

Author(s):

Jin Peng ◽

Liqun Li ◽

Shangyang Lin ◽

Furong Zhang ◽

Qinglong Pan ◽

...

Keyword(s):

Aluminum Alloy ◽

Laser Welding ◽

Welding Speed ◽

Molten Pool ◽

High Speed ◽

Numerical Study ◽

Flow Behavior ◽

Front Wall ◽

X Ray ◽

Rear Part

By using the X-ray transmission imaging system, melt flows inside a molten pool were studied during laser welding of aluminum alloy at different welding speeds. Then, the correlation between temperature gradients along the direction of weld penetration and melt flows in the rear part of a molten pool was analyzed by using a three-dimensional numerical method. And the presented model was verified by experimental results. The corresponding investigation was carried out to further study the correlation between temperature gradient and melt flow behavior of the molten pool in the plate heated by preheating temperature. The results indicated that, in the rear part of the molten pool, the maximum flow velocity was located at the bottom of the molten pool. The melt metal in the rear molten pool caused by different welding speeds had significantly different flow trends. As the welding speed increased, the absorbed intensity on the keyhole front wall also increased as well as the recoil pressure that could maintain the keyhole opened. Consequently, the increase of the welding speed was more beneficial to improving the stability of the molten pool.

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