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.

Restoration and Enhancement of X-Ray Images of Molten Pool during Laser Deep Penetration Welding

2012 ◽  
Vol 201-202 ◽  
pp. 356-359
Author(s):  
Jun Bin Xiang ◽  
Xiang Dong Gao
Keyword(s):  
Molten Pool ◽  
High Speed ◽  
Blind Deconvolution ◽  
Welding Process ◽  
304 Stainless Steel ◽  
Deep Penetration ◽  
X Ray ◽  
Laser Deep Penetration Welding ◽  
Contrast Stretching ◽  
Deep Penetration Welding

Owing to a strong capability of penetration, the radiography can be used to observe and analyze the formation of a molten pool inside weldments during laser deep penetration welding. The shape of a molten pool and the thermal transmit of laser through keyhole can be monitored and analyzed in real-time. During a high-power fiber laser bead on plate welding of Type 304 stainless steel, a high-speed radiography camera was employed to capture the molten pool images. These captured X-ray images were degraded by the disturbance and noises from the welding process and radiography devices. This paper proposes an efficient arithmetic to restore and enhance the X-ray images of molten pools. The point spread function (PSF) of X-ray image degeneration was obtained through blind deconvolution, And the PSF was applied as a parameter to implement the constrained least squares filtering of X-ray image of a molten pool. Also, the X-ray image was enhanced by contrast stretching transformation. Experimental results showed that the proposed arithmetic of image restoration and enhancement could improve the quality of X-ray images efficiently and protrude the contour feature of a molten pool.

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.

Spatters during Laser Deep Penetration Welding with a Bifocal Optic

2016 ◽  
Vol 1140 ◽  
pp. 123-129 ◽  
Author(s):  
Joerg Volpp ◽  
Jennifer Srowig ◽  
Frank Vollertsen
Keyword(s):  
Energy Efficient ◽  
High Speed ◽  
Stable Process ◽  
Welding Process ◽  
Industrial Applications ◽  
Deep Penetration ◽  
Laser Deep Penetration Welding ◽  
Deep Penetration Welding ◽  
Processing Steps ◽  
Weld Seams

The energy efficient, high-speed laser deep penetration welding process is a technology which is increasingly used for industrial applications. In order to guarantee weld seams of high quality a stable process needs to be established. Especially when welding aluminium alloys the weld quality is reduced due to occurring spatters which entails a loss of material. Solidified spatters remain on the surface of the specimen after welding and need to be cleaned for further processing steps. One method to change the process behaviour is beam shaping. In this work, a bifocal optic is used to produce two foci along the beam axis in order to manipulate the energy input into the keyhole. Bead-on-plate welds are produced in aluminium alloy EN AW-6082 and mild steel S235. For comparison, welding is conducted using standard optics. The spatter occurrence is compared when using these different beam shapes. While a reduced number of spatters per time are observed the spatter size increases when using the bifocal optic in this study.

Laser-Arc Hybrid Welding Process of Galvanized Steel Sheets

2008 ◽  
Vol 580-582 ◽  
pp. 355-358 ◽  
Author(s):  
Souta Matsusaka ◽  
Toshiro Uezono ◽  
Takuya Tsumura ◽  
Manabu Tanaka ◽  
Takehiro Watanabe
Keyword(s):  
Laser Beam ◽  
Welding Speed ◽  
High Speed ◽  
Incidence Angle ◽  
Welding Process ◽  
Galvanized Steel ◽  
Mag Welding ◽  
Hybrid Process ◽  
Deep Penetration ◽  
Steel Sheets

Galvanized steel sheets with a lap joint were welded by a laser-arc hybrid process. The hybrid system consisted of 2kW LD or YAG laser oscillator and frequency-modulated DC pulsed MAG welding machine. In this experiment, the arc traveled on the specimens, following the laser beam with the interval of 2 mm. The results showed that the hybrid process had some advantages, such as deep penetration depth, high welding speed and high gap-tolerance, in comparison with the conventional MAG welding. Observations from a high-speed digital video-camera suggested that the zinc and iron vapors induced by laser beam irradiation stabilized the arc plasma. Effects of the incidence angle between a welding head and a specimen on the weld bead formations were also discussed. As a result, the welding speed of 2.0 m/min was achieved at 1.0 mm of gap length condition when the incidence angle was 50 degree.

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 Experimental analysis of key parameters of laser fion welding of honeycomb plate heat exchanger

2019 ◽  
Vol 23 (5 Part A) ◽  
pp. 2757-2764
Author(s):  
Xinwu Du ◽  
Xin Jin ◽  
Huangzhen Lv ◽  
Shiguang Wang
Keyword(s):  
Heat Exchanger ◽  
Welding Process ◽  
Plate Heat Exchanger ◽  
Deep Penetration ◽  
Optimal Arrangement ◽  
Weld Shape ◽  
Plate Heat ◽  
Laser Deep Penetration Welding ◽  
Deep Penetration Welding ◽  
Hydraulic Bulging

The combination of laser deep penetration welding and hydraulic bulging is the most advanced production technology of honeycomb plate heat exchanger in the world. The micro-shape and heat transfer effect of the heat exchanger of honeycomb plate are mainly determined by the distribution mode of welding spot, weld shape and welding point arrangement. Therefore, the important principle of the honeycomb plate heat exchanger processing is to improve the pressure as much as possible to form turbulence while ensuring the welding quality. In the present experimental work, the effect of different weld shape and weld distribution of honeycomb plate heat exchanger produced by 06cr19n10 plate using hydraulic bulging and laser deep penetration welding on hydraulic bulging effect was studied carefully. The results showed that the optimal arrangement method is the equilateral triangle. The welding process parameters were optimized to increase the welding strength. The results showed that when the welding power was 2.1 kW, the bonding strength of the weld was the highest, at 52.70 kN. When the welding power was 2.2 kW and the gap between the welding points was 30 mm, the tensile strength of the honeycomb plate was the best, at 19.0 MPa. The results of this paper provide experimental support for industrial production of honeycomb plate heat exchanger.

Characteristic of Hyperbaric GMAW Metal Transfer at 1-12 Bar Argon Environment

2014 ◽  
Vol 900 ◽  
pp. 565-569
Author(s):  
Kai Li ◽  
Hong Ming Gao ◽  
Hai Chao Li ◽  
Shan Gong
Keyword(s):  
High Speed ◽  
Ambient Pressure ◽  
Welding Process ◽  
Axial Direction ◽  
Metal Transfer ◽  
Large Droplet ◽  
Camera System ◽  
Transfer Mode ◽  
Feeding Speed ◽  
Different Characteristics

The metal transfer behavior in hyperbaric GMAW process was investigated by using a high speed camera system with infrared laser as backlight. The metal transfer mode at 1-12bar argon environment shows different characteristics. Three kinds were observed: large droplet repelled transfer, projected repelled transfer and hyperbaric streaming transfer. Large droplet repelled transfer occurs mostly in the welding process with low feeding speed and relatively low welding voltage. Projected repelled transfer appears at middle feeding speed and high ambient pressure. Transfer tracks of former two modes deviate from the axial direction of welding wire. The spatter is produced more frequently in the projected repelled transfer mode. Hyperbaric streaming transfer is found meanly at high feeding speed and relatively high voltage. Because of its stability reflected from metal transfer process, hyperbaric GMAW process with hyperbaric streaming transfer mode should be employed preferentially.

scholarly journals Calculation of hardening process parameters for locomotive parts

2018 ◽  
Vol 216 ◽  
pp. 02020 ◽  
Author(s):  
Alexander Buynosov ◽  
Vasily Lapshin ◽  
Alexander Smolyaninov ◽  
Albert Dinislamov
Keyword(s):  
High Speed ◽  
Theoretical Models ◽  
High Energy ◽  
Major Effect ◽  
High Energy Density ◽  
Deep Penetration ◽  
Hardening Process ◽  
Heat Hardening ◽  
Uniform Temperature Field ◽  
Deep Penetration Welding

The existing theoretical models of heating by concentrated sources with a high energy density generally describe processes with deep penetration welding of part surfaces. The purpose of this study is to identify the factors that have a major effect on hardening of parts through heat treatment with a high-speed or pulsed scanning stationary heat source, which creates a uniform temperature field. Using methods of regression analysis, the authors derived equations for calculating the hardening depth in the proposed hardening process, the rate and time of steel cooling in a critical temperature range. The paper presents the calculated parameters of the hardening process in which parts, including wheel flanges of locomotives, are heated by a plasma arc in nitrogen. The findings can be used to reduce costs of complex experiments aimed at selecting surface heat hardening parameters to increase the service life of locomotive mechanical parts.

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 OCT Capillary Depth Measurement in Copper Micro Welding Using Green Lasers

2021 ◽  
Vol 11 (6) ◽  
pp. 2655
Author(s):  
Tobias Beck ◽  
Christoph Bantel ◽  
Meiko Boley ◽  
Jean Pierre Bergmann
Keyword(s):  
Laser Welding ◽  
Process Monitoring ◽  
Weld Seam ◽  
Welding Process ◽  
Direct Determination ◽  
Deep Penetration ◽  
Scanning System ◽  
Depth Measurement ◽  
Aspect Ratios ◽  
Deep Penetration Welding

The transition of the powertrain from combustion to electric systems increases the demand for reliable copper connections. For such applications, laser welding has become a key technology. Due to the complexity of laser welding, especially at micro welding with small weld seam dimensions and short process times, reliable in-line process monitoring has proven to be difficult. By using a green laser with a wavelength of λ=515, the welding process of copper benefits from an increased absorption, resulting in a shallow and stable deep penetration welding process. This opens up new possibilities for the process monitoring. In this contribution, the monitoring of the capillary depth in micro copper welding, with welding depth of up to 1 , was performed coaxially using an optical coherence tomography (OCT) system. By comparing the measured capillary depth and the actual welding depth, a good correlation between two measured values could be shown independently of the investigated process parameters and stability. Measuring the capillary depth allows a direct determination of the present aspect ratio in the welding process. For deep penetration welding, aspect ratios as low as 0.35 could be shown. By using an additional scanning system to superimpose the welding motion with a spacial oscillating of the OCT beam perpendicular to the welding motion, multiple information about the process could be determined. Using this method, several process information can be measured simultaneously and is shown for the weld seam width exemplarily.

Sign in / Sign up

Export Citation Format

Share Document