Characteristics of the Keyhole and Energy Absorption during YAG Laser Welding of Al-Li Alloy

2011 ◽  
Vol 287-290 ◽  
pp. 2401-2406 ◽  
Author(s):  
Ai Qin Duan ◽  
Shui Li Gong
Keyword(s):  
Laser Welding ◽  
Heat Input ◽  
High Speed ◽  
Laser Energy ◽  
Welding Parameters ◽  
High Speed Camera ◽  
Welding Time ◽  
Welding Condition ◽  
Yag Laser ◽  
Temperature Area

In this paper, the keyhole of YAG laser welding 5A90 Al-Li alloy was observed and measured through the high speed camera. The characteristics of the keyhole and the effects of welding parameters were studied. The characteristics of the absorption of laser energy and the susceptivity for heat input in welding 5A90 were given. The results show that in this welding condition, the keyhole of laser welding 5A90 is nearly a taper and the highest temperature area is in the bottom. There are clear effects of heat input on the characteristics, especially the surface radius of keyhole and plasma/vapor in keyhole. Another phenomena is observed that sometime plasma/vapor could disappear in 0.3ms welding time, and this feature will be more remarkable as decrease of heat input. It shows that the absorption of energy is unsteady. It is known that when this instability reaches a certain value, an unsteady weld will be formed.

Experiment Research of Laser Induced Air Breakdown

2014 ◽  
Vol 599-601 ◽  
pp. 201-204
Author(s):  
Hai Dong Wu
Keyword(s):  
Energy Conversion ◽  
High Speed ◽  
Laser Excitation ◽  
Laser Energy ◽  
Ionization Process ◽  
High Speed Camera ◽  
Experiment Research ◽  
Sound Energy ◽  
Air Breakdown

The principle of laser induced air breakdown was introduced. The laser energy conversion in ionization process was studied. The phenomenon of laser induced air breakdown was observed by using high speed camera. It was found that a higher laser energy induced more laser energy to transfer into light and sound energy. The plasma reached maximum in shape in about 20 to 30 ns after laser excitation, and disappeared in about 16μs.

scholarly journals In Situ and Post-Mortem Characterizations of Ultrasonic Spot Welded AZ31B and Coated Dual Phase 590 Steel Joints

Metals ◽  
2020 ◽  
Vol 10 (7) ◽  
pp. 899 ◽  
Author(s):  
Jian Chen ◽  
Yong Chae Lim ◽  
Donovan Leonard ◽  
Hui Huang ◽  
Zhili Feng ◽  
...  
Keyword(s):  
High Speed ◽  
Tensile Tests ◽  
Fatigue Tests ◽  
Image Correlation ◽  
Joint Interface ◽  
Welding Time ◽  
Cross Sectional ◽  
Welding Condition ◽  
Lap Shear

Ultrasonic spot welding using different welding conditions was applied to join dissimilar metals of galvanized DP590 steel and AZ31B magnesium sheets. In situ high-speed imaging, digital image correlation, and infrared thermography were utilized to quantitatively study the interfacial relative motion, surface indentation, and heat generation across the joint faying interface and the sheet/sonotrode interfaces under the welding condition of moderate welding power and short welding time. For welds made with high power and long welding time, lap shear tensile tests as well as fatigue tests were carried out. Different fracture modes were observed after the lap shear tensile tests and fatigue tests performed under different peak loads. Post-weld cross-sectional analysis with scanning electron microscopy coupled with energy dispersive X-Ray spectroscopy revealed the variation of morphology and chemical composition at the joint interface for welds made with different welding conditions.

Spectroscopic Analysis of the Plasma in Laser Welding of AZ31 Magnesium Alloy

2013 ◽  
Vol 341-342 ◽  
pp. 296-300
Author(s):  
Xiao Yan Gu ◽  
Huan Li ◽  
Ying Gao
Keyword(s):  
Magnesium Alloy ◽  
Laser Welding ◽  
Laser Plasma ◽  
Spectroscopic Analysis ◽  
Plasma Temperature ◽  
Cooling Effect ◽  
Az31 Magnesium Alloy ◽  
Welding Parameters ◽  
Yag Laser ◽  
The Relationship

AZ31 magnesium alloy was welded by the YAG laser. The plasma of laser welding was studied by the spectra and the plasma temperature was also calculated. The relationship between the welding parameters and plasma temperature was studied. The paper shows that the cooling effect of the plasma using helium is significant. Laser plasma temperature decreases from the center to the periphery and the temperature in the center is higher than 9000K. The evaporation of Mg element concentrates in the center of the laser plasma.

Effects of Nd: YAG Laser Welding Parameters on the Microstructure of 21% Cr Ferritic Stainless Steel

2011 ◽  
Vol 291-294 ◽  
pp. 999-1002
Author(s):  
Ke Ping Geng ◽  
Sheng Sun Hu ◽  
Jun Qi Shen ◽  
Jian Han ◽  
Hai Gang Xu
Keyword(s):  
Laser Welding ◽  
Optical Microscope ◽  
Welding Parameters ◽  
Slow Cooling ◽  
Yag Laser ◽  
Average Grain Size ◽  
Electron Microscopes ◽  
Scanning Electron Microscopes ◽  
The Relationship ◽  
Scanning Electron

21% Cr with Ti-Nb dual stabilized ferritic stainless was welded using Nd: YAG laser. The relationship between microstructure and parameters of laser welding was examined. The microstructure was investigated by using the optical microscope and scanning electron microscopes. The average grain size of the HAZ was increased with increasing heat input due to the slow cooling rate. Large precipitates as TiN, TiC and Nb(C,N) were dissolved in the HAZ. Fine precipitates which supposed to be TiC was formed uniformly distributed in the case of the fusion zones.

Study on the Characteristics of Contact Line and Liquid Film in Rectangular Microgrooves Under Vibration Conditions

2011 ◽  
Author(s):  
Wei Cao ◽  
Xuegong Hu ◽  
Chaohong Guo ◽  
Dawei Tang
Keyword(s):  
Liquid Film ◽  
Contact Line ◽  
Heat Input ◽  
High Speed ◽  
Mechanical Vibration ◽  
Line Length ◽  
Oscillation Period ◽  
Wide Field ◽  
High Speed Camera ◽  
Phase Contact

With the help of a high-speed camera (30000 Frames/second) and a wide-field stereo-microscope, the effects of mechanical vibration on the meniscus film and triple-phase contact line in rectangular microgrooves were experimentally investigated. Distilled water was used as working liquid. The images of the oscillated meniscus film in an oscillation period were captured through the high speed camera and they were analyzed using a MATLAB program. The results show that as the vibration table moves upward, the length of contact line increases; as the vibration table moves downward, the length of contact-line decreases. During the oscillation, the axial liquid film spreads upward further along the microgrooves and the deformation of the contact line becomes more obvious. The increase of the triple-phase contact line length caused by the external mechanical vibration is helpful for contact line heat transfer enhancement. Besides, deformation curve of the contact line with and without heat input under different vibration conditions is similar, while the contact line with heat input is shorter.

scholarly journals Effect of Heat Input During Disk Laser Bead-On-Plate Welding of Thermomechanically Rolled Steel on Penetration Characteristics and Porosity Formation in the Weld Metal

2016 ◽  
Vol 61 (1) ◽  
pp. 93-102 ◽  
Author(s):  
A. Lisiecki
Keyword(s):  
Laser Welding ◽  
Heat Input ◽  
Welding Parameters ◽  
Depth Of Penetration ◽  
Porosity Formation ◽  
Disk Laser ◽  
Full Penetration ◽  
Wide Range ◽  
Weld Porosity ◽  
The Relationship

The paper presents a detailed analysis of the influence of heat input during laser bead-on-plate welding of 5.0 mm thick plates of S700MC steel by modern Disk laser on the mechanism of steel penetration, shape and depth of penetration, and also on tendency to weld porosity formation. Based on the investigations performed in a wide range of laser welding parameters the relationship between laser power and welding speed, thus heat input, required for full penetration was determined. Additionally the relationship between the laser welding parameters and weld quality was determined.

Analysis of laser welding keyhole characteristics based on near-infrared high speed camera and X-ray sensing

2016 ◽  
Vol 24 (10) ◽  
pp. 2400-2407
Author(s):  
高向东 GAO Xiang-dong ◽  
李竹曼 LI Zhu-man ◽  
游德勇 YOU De-yong ◽  
张南峰 ZHANG Nan-feng
Keyword(s):  
Laser Welding ◽  
High Speed ◽  
Near Infrared ◽  
High Speed Camera ◽  
X Ray

Microstructure and Mechanical Properties of Laser Welding Joint of Inconel 718 Super Thin Sheet

2011 ◽  
Vol 391-392 ◽  
pp. 479-483 ◽  
Author(s):  
Shu Guo Zhang ◽  
Yu Hua Chen ◽  
Jun Hua Cui
Keyword(s):  
Laser Welding ◽  
Inconel 718 ◽  
Gas Flow ◽  
Focal Point ◽  
Thin Sheet ◽  
Weld Zone ◽  
Base Material ◽  
Welding Parameters ◽  
Yag Laser ◽  
Welding Joint

Nd-YAG laser welding characteristics of Inconel 718, microstructures,tensile properties,and hardness of welding joint were researched. Nd-YAG laser welding was carried out on super thin Inconel 718 sheet(0.2 mm thick) with 6 specimens. The welding parameters of these specimens are varied expect for the welding speed(0.3mm/s), gas-flow rate (5L/min) and clearance between focal point and (plate) surface(0).In this research,the tensile strength of welding joint was found to be inferior to base metal and the ductility of welds was considerably lower than base material,the microhardness in weld zone is higher than the base material hardness and the hardness is highest in center zone of welding joint. These conclusions will be in favour of the manufacture with super thin Inconel 718.

Interactions of the process parameters and mechanical properties of laser butt welds in thin high strength low alloy steel plates

2020 ◽  
Vol 234 (5) ◽  
pp. 665-680 ◽  
Author(s):  
Patricio Gustavo Riofrío ◽  
Carlos Alexandre Capela ◽  
José AM Ferreira ◽  
Amilcar Ramalho
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Laser Welding ◽  
Alloy Steel ◽  
Heat Input ◽  
High Strength ◽  
Welding Parameters ◽  
Bead Geometry ◽  
Low Alloy Steel ◽  
Weld Bead Geometry

High strength low alloy steels subjected to the thermomechanical control process present excellent strength–toughness combination, high strength/weight ratio, and weldability. Therefore, they are widely used in structural components, such as pressure vessels, oil/gas transportation pipes, lifting equipment, vehicles, shipbuilding and offshore industries, and in the automotive industry where low thickness (0.8–3 mm thickness) is of great importance. Usually, these steels are welded by conventional gas metal arc welding, which creates wide heat-affected zones, large residual stresses, and distortion in the welded parts. Laser welding is nowadays an alternative process to weld high strength low alloy steel parts due to its advantages. The aim of this work is to understand the effect of process parameters on defects, weld bead geometry, microstructure, and mechanical properties, namely hardness and tensile strength. We identify the main laser welding parameters and their influence on the weld bead geometry and defects, for a 3 mm thick high strength low alloy steel welded under a maximum power of 2 kW. A cross section of the weld seam was optimized achieving a good geometry without porosity. The threshold value of the heat input to achieve complete penetration was determined for different focus diameters. The microstructure, size, and hardness of the heat-affected zone and of the fusion zone are strongly influenced by the heat input. The values of the tensile strength achieved in butt welds were close to the base metal by an appropriate selection of the laser welding parameters and the heat input.

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