scholarly journals An Experimental Approach for the Direct Measurement of Temperatures in the Vicinity of the Keyhole Front Wall during Deep-Penetration Laser Welding

2020 ◽  
Vol 10 (11) ◽  
pp. 3951
Author(s):  
Ronald Pordzik ◽  
Peer Woizeschke
Keyword(s):  
Laser Welding ◽  
Boiling Point ◽  
High Speed ◽  
Pure Aluminum ◽  
Welding Process ◽  
Deep Penetration ◽  
Front Wall ◽  
Melt Pool ◽  
Direct Laser ◽  
Welding Processes

The formation of defects such as pores during deep-penetration laser welding processes is governed by the melt pool dynamics and the stability of the vapor capillary, also referred to as the keyhole. In order to gain an insight into the dynamics of the keyhole, the temperature in the transition region from the liquid to the gaseous phase, i.e., near the keyhole wall, is a physical value of fundamental importance. In this paper, a novel method is presented for directly measuring temperatures in the close vicinity of the keyhole front wall during deep-penetration laser welding. The weld samples consist of pure aluminum with a boiling point of 2743 K. The measurement is performed using high-speed pyrometry with a refractory tantalum probe capable of detecting temperatures that significantly exceed the boiling point of the sample material. Temperature curves are recorded from the beginning of the welding process until the moment the probe is finally destroyed through direct laser-tantalum interaction. With an effective spatial resolution up to 0.3 µm in the welding direction, a detailed investigation into the temperature ranging from the prerunning melt pool front to the keyhole center is possible, exhibiting temperatures of up to 3300 K in the vicinity of the keyhole front wall.

Color Image Segmentation of Plume for Monitoring Disk Laser Welding Process

2012 ◽  
Vol 201-202 ◽  
pp. 166-169
Author(s):  
Teng Wang ◽  
Xiang Dong Gao
Keyword(s):  
Image Segmentation ◽  
Laser Welding ◽  
High Speed ◽  
Clustering Algorithm ◽  
Color Image ◽  
Color Space ◽  
Welding Process ◽  
Metal Vapor ◽  
Color Image Segmentation ◽  
Deep Penetration

During deep penetration laser welding, changes in the metal vapor plume contain information about the stability of welding process. A high-speed camera was used to online monitor the welding process in order to detect the laser welding defects. A color segmentation clustering algorithm based on HSI color space was proposed for processing the recorded welding sequences. The effectiveness of algorithms based on different model is discussed, welding experimental results showed that the proposed algorithm could achieve better image segmentation, and it highlighted the edge of the metal vapor details in the image.

scholarly journals Influence of Magnesium on Spatter Behavior in Laser Deep Penetration Welding of Aluminum Alloys

2019 ◽  
Vol 3 (3) ◽  
pp. 71
Author(s):  
Felsing ◽  
Woizeschke
Keyword(s):  
Aluminum Alloys ◽  
High Speed ◽  
Pure Aluminum ◽  
Welding Process ◽  
Magnesium Content ◽  
Flight Path ◽  
Deep Penetration ◽  
Camera System ◽  
Flight Path Angle ◽  
Deep Penetration Welding

The quality of welds, as well as the necessity of post-processing, is challenged by spatter generation during the laser keyhole welding process. In this study, the influence of the magnesium content on spatter behavior is studied for three aluminum alloys (Al99.5, AlMg3, and AlMg5). A synchronized dual high-speed camera system is used to observe the spatter behavior and to reconstruct 3D spatter trajectories as well as determine the characteristics of spatter velocity, flight path angle, and approximate spatter size. The mean spatter velocities and flight path angles of the welding experiments with the three alloys were in welding direction between 4.1 m/s and 4.6 m/s and 44.8° and 51.0°, respectively. Furthermore, the AlMg alloys show excessive spatter behavior with spray events of more than 50 spatters at a time, and less frequently spatter explosions. Spatter spray events show a character similar to spatter explosions. Volumetric evaporation is proposed as effecting these events. In contrast, and resulting from a different mechanism, pure aluminum (Al99.5) shows group ejection events with at least 10 spatters at a time. In this study, there are no correlations between spatter velocities and flight path angles, nor between velocities and approximate spatter sizes.

Microstructure and mechanical property improvement of dissimilar metal joints for TC4 Ti alloy to Nitinol NiTi alloy by laser welding

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Yan Zhang ◽  
DeShui Yu ◽  
JianPing Zhou ◽  
DaQian Sun ◽  
HongMei Li
Keyword(s):  
Tensile Strength ◽  
Laser Welding ◽  
Mechanical Performance ◽  
Niti Alloy ◽  
Welding Process ◽  
Ti Alloy ◽  
The One ◽  
Fusion Weld ◽  
Welding Processes ◽  
Cu Interlayer

Abstract To avoid the formation of Ti-Ni intermetallics in a joint, three laser welding processes for Ti alloy–NiTi alloy joints were introduced. Sample A was formed while a laser acted at the Ti alloy–NiTi alloy interface, and the joint fractured along the weld centre line immediately after welding without filler metal. Sample B was formed while the laser acted on a Cu interlayer. The average tensile strength of sample B was 216 MPa. Sample C was formed while the laser acted 1.2 mm on the Ti alloy side. The one-pass welding process involved the creation of a joint with one fusion weld and one diffusion weld separated by the remaining unmelted Ti alloy. The mechanical performance of sample C was determined by the diffusion weld formed at the Ti alloy–NiTi alloy interface with a tensile strength of 256 MPa.

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

2013 ◽  
Vol 40 (5) ◽  
pp. 0503001
Author(s):  
裴莹蕾 Pei Yinglei ◽  
单际国 Shan Jiguo ◽  
任家烈 Ren Jialie
Keyword(s):  
Laser Welding ◽  
Welding Speed ◽  
High Speed ◽  
Flow Behavior ◽  
Welding Process ◽  
Melt Flow ◽  
Laser Welding Process

An Overview of GMAW Including Applications, Common Problems and Solutions

2006 ◽  
Author(s):  
Michael R. Henderson
Keyword(s):  
Proper Time ◽  
Short Circuit ◽  
Gas Metal Arc Welding ◽  
Welding Process ◽  
Deep Penetration ◽  
Deposition Rates ◽  
Thin Sections ◽  
Problems And Solutions ◽  
Common Problems ◽  
Welding Processes

Gas Metal Arc Welding (GMAW) is said to be one of the easiest welding processes to learn and use. Because of its high deposition rates and little post-weld cleaning required, GMAW is a popular choice for a variety of applications including almost all commercially important metals. Another factor contributing to the widespread use of GMAW is the various modes of metal transfer including short circuit, spray, surface tension transfer (STT), etc. These different modes of transfer enable GMAW to be tailored to different situations. For instance, some applications may require deep penetration or other applications may be for welding very thin sections. However, these factors along with others may result in inferior welds if not monitored closely. Problems such as weld porosity, lack of fusion, and lack of shielding gas coverage can all lead to inadequate welds which can lead to larger problems if not corrected. Many common drawbacks to the GMAW process can be remedied quite easily with proper time and attention. Taking the time and effort to produce a sound weld may, however, negate the superior deposition rates of GMAW thereby limiting its use to fewer applications. This welding process can be extremely effective when used properly. However, the key is to not sacrifice weld quality for the sake of production. GMAW applications, modes of transfer, along with common problems and solutions associated with the process will all be discussed and detailed.

Study of Plume Behavior during High-Power Disk Laser Welding

2012 ◽  
Vol 201-202 ◽  
pp. 1076-1079
Author(s):  
De Yong You ◽  
Xiang Dong Gao
Keyword(s):  
Laser Welding ◽  
High Power ◽  
High Speed ◽  
Welding Process ◽  
Image Sequences ◽  
Process Conditions ◽  
High Speed Photography ◽  
Disk Laser ◽  
Industrial Manufacturing ◽  
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.

scholarly journals Numerical Simulation and Industrial Application of High Speed Tandem TIG Welding

2021 ◽  
Author(s):  
Dongsheng Wu ◽  
Jiuling Huang ◽  
Kong Liang ◽  
Xueming Hua ◽  
Min Wang ◽  
...  
Keyword(s):  
Molten Metal ◽  
Weld Pool ◽  
High Speed ◽  
Metal Flow ◽  
Welding Process ◽  
Tig Welding ◽  
Pool Surface ◽  
Weld Pool Surface ◽  
Welding Processes ◽  
Molten Metal Flow

Abstract Self-developed high speed tandem TIG welding equipment were adopted to manufacture titanium welded tubes with high efficiency and high quality. The joint made by this high efficient welding process met Chinese standard requirements. A coupled electrode, arc and weld pool numerical model was also developed to investigate temperature and velocity distributions, and energy propagation of this welding process. The numerical results showed that the Marangoni stress was much higher than the arc shear stress, and was mainly positive after leading and trailing arcs in the x and y directions, so the molten metal flowed backward on the top weld pool surface. Previous studies proposed that a “pull-push” flow pattern defined as a backward molten metal flow after the leading arc and a forward molten metal flow before the trailing arc existed on the top weld pool surface in tandem arc welding processes, while it was not observed in this case. The calculated arc efficiency of the high speed tandem TIG welding was about 79.8%.

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