Understanding of Laser and Hybrid Welding Phenomena

2008 ◽  
Vol 580-582 ◽  
pp. 535-538 ◽  
Author(s):  
Seiji Katayama ◽  
Yousuke Kawahito ◽  
Masami Mizutani
Keyword(s):  
Stainless Steel ◽  
Aluminum Alloy ◽  
Fusion Zone ◽  
Molten Pool ◽  
Bubble Formation ◽  
Hybrid Welding ◽  
Laser Weld ◽  
Pool Surface ◽  
Weld Fusion Zone ◽  
Keyhole Behavior

This paper describes laser and hybrid welding phenomena for the production of a sound and deep weld. The penetration of laser weld beads depended upon the power and power density at low and high welding speeds, respectively. It was reveled that the weld fusion zone geometry was formed by keyhole behavior and melt flows. It was also understood that the production of sound welds without porosity was attributed to no bubble formation in TIG-YAG hybrid welding of stainless steel and the disappearance of bubbles from the molten pool surface in YAG-MIG hybrid welding of aluminum alloy.

scholarly journals Microstructural Characterization of Laser Weld of Hot-Stamped Al-Si Coated 22MnB5 and Modification of Weld Properties by Hybrid Welding

Materials ◽  
2021 ◽  
Vol 14 (14) ◽  
pp. 3943
Author(s):  
Hana Šebestová ◽  
Petr Horník ◽  
Šárka Mikmeková ◽  
Libor Mrňa ◽  
Pavel Doležal ◽  
...  
Keyword(s):  
Tensile Strength ◽  
Ultimate Tensile Strength ◽  
Fusion Zone ◽  
Microstructural Characterization ◽  
Tensile Tests ◽  
Laser Weld ◽  
Martensitic Microstructure ◽  
Laser Welds ◽  
Weld Properties ◽  
Weld Fusion Zone

The presence of Al-Si coating on 22MnB5 leads to the formation of large ferritic bands in the dominantly martensitic microstructure of butt laser welds. Rapid cooling of laser weld metal is responsible for insufficient diffusion of coating elements into the steel and incomplete homogenization of weld fusion zone. The Al-rich regions promote the formation of ferritic solid solution. Soft ferritic bands cause weld joint weakening. Laser welds reached only 64% of base metal's ultimate tensile strength, and they always fractured in the fusion zone during the tensile tests. We implemented hybrid laser-TIG welding technology to reduce weld cooling rate by the addition of heat of the arc. The effect of arc current on weld microstructure and mechanical properties was investigated. Thanks to the slower cooling, the large ferritic bands were eliminated. The hybrid welds reached greater ultimate tensile strength compared to laser welds. The location of the fracture moved from the fusion zone to a tempered heat-affected zone characterized by a drop in microhardness. The minimum of microhardness was independent of heat input in this region.

Investigation of porosity in rotating laser-MIG hybrid welding A6N01 aluminum alloy

2019 ◽  
Vol 33 (01n03) ◽  
pp. 1940029
Author(s):  
Yanjie Yin ◽  
Hui Chen ◽  
Xiaoyi Yang ◽  
Shuang He
Keyword(s):  
Aluminum Alloy ◽  
Molten Pool ◽  
High Speed ◽  
Rotation Frequency ◽  
Good Prospect ◽  
Hybrid Welding ◽  
Weld Penetration ◽  
X Ray ◽  
Conventional Laser ◽  
Alloy Weld

In this study, rotating laser was employed to reduce the porosity defect in laser-MIG hybrid welding A6N01 aluminum alloy. The influence of laser rotating frequency and rotating radius on the weld were researched respectively. The images of the molten pool were acquired by the high-speed camera, and X-ray images of the weld were calculated by binarization. The result shows that rotating laser-MIG hybrid welding has a dramatic effect on suppressing the generation of porosity, which indicates the possibility to obtain the A6N01 aluminum alloy weld with few pores. With proper parameters about rotation frequency (50 Hz) and rotation radius (2 mm), the porosity decreased obviously from 8.41% to 5.68%, and there was hardly distinct change in the weld penetration. The keyhole stability of rotating laser-MIG hybrid welding was improved, compared with the conventional laser-MIG hybrid welding. On account of laser beam stirring the metal molten pool, it was beneficial for the pores to escape from the molten pool. The rotating laser-MIG hybrid welding shows a good prospect.

Laser Weldability of Aluminum Alloy and Steel

2005 ◽  
Vol 502 ◽  
pp. 481-486 ◽  
Author(s):  
Seiji Katayama ◽  
Sung Min Joo ◽  
Masami Mizutani ◽  
Han Sur Bang
Keyword(s):  
Aluminum Alloy ◽  
Fusion Zone ◽  
Dissimilar Materials ◽  
High Strength ◽  
Butt Joint ◽  
Joint Interface ◽  
Butt Joints ◽  
Alloy Base ◽  
Lap Welding ◽  
Weld Fusion Zone

With the intention of improving butt or lap joint of dissimilar materials, specially devised weld beads together with lap and butt-joints were produced between A5052 and SPCC, where A5052 butt-joint was melted by heat-conduction of SPCC weld bead in addition to the formation of a limited weld fusion zone at the lap part in A5052 alloy. The thickness of intermetallic compounds at the butt-joint interface was approximately 2 μm and free of cracks. It was also revealed that crack-free lap weld metals were formed between aluminum alloy and steel when the penetration was controlled to be of less than 0.3 mm in depth at small heat input. It was moreover found that the majority of a laser weld fusion zone solidified as alpha(bcc)-iron phase containing small amount of aluminum, and cracks were absent in the case of hard intermetallic (AlxFey type) layer of less than 10μm zone. It was confirmed that a weld with lap and butt joints possessed high strength (leading to the load 3500 N to 4,380 N for 40 mm width specimen). In addition, SPCC and A1100 or A5052 were subjected to lap welding with a cw YAG laser, where one to three passes were performed to produce wider bonded areas. Dissimilar steel and aluminum joints with good mechanical properties were obtained, since the fracture occurred in the aluminum alloy base metal in the tensile test. It is concluded that welded joints of high strength can be produced between aluminum alloy and steel with proper devices.

scholarly journals Effect of Droplet Transition on the Dynamic Behavior of the Keyhole during 6061 Aluminum Alloy Laser-MIG Hybrid Welding

2021 ◽  
Author(s):  
Yue Li ◽  
Yanqiu Zhao ◽  
Xudong Zhou ◽  
Xiaohong Zhan
Keyword(s):  
Aluminum Alloy ◽  
Dynamic Behavior ◽  
Molten Pool ◽  
High Speed ◽  
Welding Process ◽  
Welding Parameters ◽  
Hybrid Welding ◽  
Camera System ◽  
6061 Aluminum Alloy ◽  
Droplet Transition

Abstract The simulation method in laser-MIG hybrid welding, which involves two heat sources and multiple welding parameters, is beneficial to reveal the complex physical phenomena and dynamic behavior of molten pool keyhole during welding process. In this investigation, laser-MIG hybrid welding for 6-mm-thick 6061 aluminum alloy was performed under different heat input by the high-power disc laser, MIG welding system and KUKA Robot. The high-speed camera system was used to observe the droplet transition phenomenon in the welding process. Besides, a thermal-fluid coupling model was established to simulate the temperature field and flow field, which were changed by the droplet transfer during laser-MIG hybrid welding. The experimental and simulated results showed that the droplet transition behavior affected the formation of the keyhole. The keyhole was the smallest when the droplet contacted the molten pool. In addition, the droplet transition brought external momentum and energy to the molten pool, which was conducive to the increase of the flow rate of the molten pool.

scholarly journals Simulation Study on Weld Formation in Full Penetration Laser + MIG Hybrid Welding of Copper Alloy

Materials ◽  
2020 ◽  
Vol 13 (23) ◽  
pp. 5307
Author(s):  
Feipeng An ◽  
Qilong Gong ◽  
Guoxiang Xu ◽  
Tan Zhang ◽  
Qingxian Hu ◽  
...  
Keyword(s):  
Molten Pool ◽  
Copper Alloy ◽  
Fluid Dynamic ◽  
Dynamic Feature ◽  
Hybrid Welding ◽  
Alloy Plate ◽  
Butt Welding ◽  
Weld Formation ◽  
Full Penetration ◽  
Keyhole Behavior

Considering the coupling of a droplet, keyhole, and molten pool, a three-dimensional transient model for the full penetration laser + metal inert gas (MIG) hybrid welding of thin copper alloy plate was established, which is able to simulate the temperature and velocity fields, keyhole behavior, and generation of the welding defect. Based on the experimental and simulation results, the weld formation mechanism for the hybrid butt welding of a 2 mm-thick copper alloy plate was comparatively studied in terms of the fluid dynamic feature of the melt pool. For single laser welding, the dynamic behavior of liquid metal near the rear keyhole wall is complex, and the keyhole has a relatively drastic fluctuation. An obvious spattering phenomenon occurs at the workpiece backside. Meanwhile, the underfill (or undercut) defect is formed at both the top and bottom surfaces of the final weld bead, and the recoil pressure is identified as the main factor. In hybrid welding, a downward fluid flow is strengthened on the rear keyhole wall, and the stability of the keyhole root is enhanced greatly. There are large and small clockwise vortexes emerging in the upper and lower parts of the molten pool, respectively. A relatively stable metal bulge can be produced at the weld pool backside. The formation defects are suppressed effectively, increasing the reliability of full penetration butt welding of the thin copper alloy plate.

Fatigue Crack Growth Rate and Fracture Resistance of Heat Affected Zone of Type 316L Stainless Steel With Narrow Gap Welds

2011 ◽  
Author(s):  
Ho-Jung Lee ◽  
Minu Kim ◽  
Changheui Jang ◽  
Sun-Young Cho ◽  
Jun-Seog Yang
Keyword(s):  
Growth Rate ◽  
Stainless Steel ◽  
Fatigue Crack ◽  
Crack Growth Rate ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Fusion Zone ◽  
Fracture Resistance ◽  
Narrow Gap ◽  
Weld Fusion Zone

In nuclear power plants, the automated narrow gap welding (NGW) technique has been widely used in joining pipes in primary coolant system. Meanwhile, to apply the leak-before-break (LBB) design, mechanical properties of the structural materials of piping systems should be evaluated, especially at various welded joints. In this study, the fatigue crack growth rate (FCGR) and fracture resistance of stainless steel weld fusion zone and nearby heat affected zone (HAZ) were evaluated to support the LBB application. Tests were performed at plant operating temperature (315°C) and room temperature. FCGR test results showed higher crack growth rate in HAZ and the weld fusion zone compare to the base metal. Fracture resistance tests showed higher fracture toughness in HAZ compared to the weld fusion zone. By analyzing the microstructures in the weld fusion zone and HAZ, their effects on crack growth rate were discussed. Also, the crack growth behavior in circumferential direction was compared with that in radial direction which was previously reported.

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