Monitoring of the Spatter Formation in Laser Welding of Galvanized Steels in Lap Joint Configuration by the Measurement of the Acoustic Emission

2008 ◽  
Author(s):  
Shanglu Yang ◽  
Wei Huang ◽  
Dechao Lin ◽  
Fanrong Kong ◽  
Radovan Kovacevic
Keyword(s):  
Acoustic Emission ◽  
Laser Welding ◽  
Zinc Coating ◽  
Welding Process ◽  
Lap Joint ◽  
Galvanized Steels ◽  
Wide Range ◽  
Metal Sheets ◽  
On Line ◽  
Ae Signals

Galvanized steels have been widely used in the different industries such as automotive, aerospace and marine industry, due to their high corrosion resistance and excellent mechanical properties. However, the zinc coating on the metal sheet offers a big challenge to the welding operation, specifically in the high-power laser welding process of the lap joint if the metal sheets are installed in a gap-free configuration. Spatters, one of the critical problems for the weld quality, is readily generated by the high-pressurized zinc vapor developed at the interface of two metal sheets. It takes extra procedures to clean the weld surface or repair the blowholes generated by the spatters. The on-line process monitoring is critical to assure the achievement of the high quality welds. Therefore, it is necessary to develop an on-line efficient monitoring system for the welding of galvanized steels. In the past few years, acoustic emission (AE) technique has been applied to monitor different manufacturing processes. This paper will highlight its application in the laser welding of galvanized steels. An AE signal acquisition system is used to real-time monitor the welding process. The results of the investigation show that the amplitude of AE signals varies with the welding process status. When the welding process is stable, the amplitudes of AE signals are almost constant and with the low intensity compared to the AE emission signals when the weld defects are presented. When the spatter is formed, a sharp spike with the high amplitude is shown in the collected acoustic emission signal. In order to extract the features of the AE signals in frequency domain, the acquired signal in time domain is further processed using Short-time Fourier Transformation (STFT). The STFT processed results indicated that the spatter-induced AE signals cover a wide range of frequencies and the background noise is mainly presented in the range below 100 Hz.

scholarly journals Interfacial Characteristics of Dissimilar Ti6Al4V/AA6060 Lap Joint by Pulsed Nd:YAG Laser Welding

Metals ◽  
2019 ◽  
Vol 9 (1) ◽  
pp. 71 ◽  
Author(s):  
Xin Xue ◽  
António Pereira ◽  
Gabriela Vincze ◽  
Xinyong Wu ◽  
Juan Liao
Keyword(s):  
Laser Welding ◽  
Nd:Yag Laser ◽  
Laser Beam Welding ◽  
Welding Process ◽  
Mechanical Resistance ◽  
Lap Joint ◽  
Important Indicator ◽  
Pulsed Nd:Yag Laser ◽  
Pulsed Nd:Yag Laser Welding ◽  
Interfacial Characteristics

This paper focuses on the interfacial characteristics of dissimilar Ti6Al4V/AA6060 lap joint produced by pulsed Nd:YAG laser beam welding. The process-sensitivity analysis of welding-induced interface joining quality was performed by using the orthogonal design method. Microstructural tests such as scanning electron microscopy and energy dispersive X-ray spectroscopy were used to observe the interfacial characteristics. The mechanism of interfacial crack initiation, which is an important indicator of joint property and performance, was assessed and analyzed. The preferred propagation paths of welding cracks along the interfaces of different intermetallic layers with high dislocation density were analyzed and discussed in-depth. The results indicate that discontinuous potential phases in the micro-crack tip would mitigate the mechanical resistance or performance of the welded joint, while the continuous intermetallic layer can lead to a sound jointing performance under pulsed Nd:YAG laser welding process.

Determining the feasibility of identifying creep rupture of stainless steel cladding tubes on-line using acoustic emission technique

2015 ◽  
Vol 6 (3) ◽  
pp. 410-418
Author(s):  
N Mahendra Prabhu ◽  
K.A. Gopal ◽  
S. Murugan ◽  
T.K. Haneef ◽  
C. K. Mukhopadhyay ◽  
...  
Keyword(s):  
Stainless Steel ◽  
Acoustic Emission ◽  
Creep Rupture ◽  
Acoustic Emission Technique ◽  
Content Type ◽  
Fuel Pin ◽  
On Line ◽  
Clad Tube ◽  
Non Destructive ◽  
Ae Signals

Purpose – The purpose of this paper is to determine the feasibility of identifying the creep rupture of reactor cladding tubes using acoustic emission technique (AET). Design/methodology/approach – The creep rupture tests were carried out by pressuring stainless steel capsules upto 6 MPa at room temperature and then heating continuously in a furnace upto rupture. The acoustic emission (AE) signals generated during the creep rupture tests were recorded using a 150 kHz resonant sensor and analysed using AE Win software. Findings – When rupture occurs in the pressurized capsule tube representing the cladding tube, AE sensor attached to a waveguide captures the mechanical disturbance from the capsule and these data can be advantageously used to identify the creep rupture event of the cladding tube. Practical implications – The creep rupture data of fuel clad tube is very important in design and for smooth operation of nuclear reactors without fuel pin failure in reactors. Originality/value – AE is an advanced non-destructive evaluation technique. This technique has been successfully applied for on-line monitoring of creep rupture of the reactor cladding tube which otherwise could be detected by thermocouple readings only.

Spectral analysis for crack detection during TIG welding using acoustic emission techniques

2020 ◽  
Vol 62 (8) ◽  
pp. 478-483
Author(s):  
Xing Meng ◽  
M Papaelias ◽  
G Melton
Keyword(s):  
Acoustic Emission ◽  
Fourier Transform ◽  
Crack Detection ◽  
High Carbon Steel ◽  
Welding Process ◽  
Frequency Domain Analysis ◽  
Tig Welding ◽  
Steel Plates ◽  
Frequency Spectra ◽  
Ae Signals

In this study, the tungsten inert gas (TIG) welding process was applied to high-carbon steel plates in order to simulate hot cracking in welds. A customised acoustic emission (AE) system was used to capture the AE waveforms generated during welding and cooling of the sample plates. The AE signals were analysed using fast Fourier transform (FFT) and short-time Fourier transform (STFT) algorithms. Comparison of the features arising from different sources observed in the frequency spectra of the acquired AE signals was carried out. The results demonstrate the possibility of applying the AE technique for monitoring and detecting signals generated from cracking activities using frequency domain analysis.

Research of Polymerization Reactor Fault Diagnosis Based on Acoustic Emission

2011 ◽  
Vol 221 ◽  
pp. 550-554
Author(s):  
Yi Hu Huang ◽  
Jin Li Wang ◽  
Hui Qiong Jiang ◽  
Xi Mei Jia ◽  
Hong Lei Chong ◽  
...  
Keyword(s):  
Acoustic Emission ◽  
Fault Diagnosis ◽  
Location Theory ◽  
Polymer Processing ◽  
New Method ◽  
Loading Process ◽  
Polymerization Reactor ◽  
Safety Production ◽  
On Line ◽  
Ae Signals

With the development and improvement of polymer processing technology, safety production requires higher and higher levels of reactor fault diagnosis and assessment. In this paper, a new method is put forward for the polymer reactor on-line fault diagnosis basing on acoustic emission (AE). During the loading process of the reactor, sensors detect the AE signals. According to the acoustic emission and location theory, the fault or flaws of the reactor can be found and located. Further, the assessment of the reactor can be got and it can guide the safety production of the reactor.

scholarly journals Laser-TIG welding of galvanized steel – numerical and experimental assessment of the effect of arc in various setups

2021 ◽  
Vol 1135 (1) ◽  
pp. 012007
Author(s):  
Hana Šebestová ◽  
Petr Horník ◽  
Jan Novotný ◽  
Libor Mrňa
Keyword(s):  
Laser Welding ◽  
Heat Input ◽  
Zinc Coating ◽  
Tig Welding ◽  
Galvanized Steel ◽  
Prolonged Heating ◽  
Interface Surface ◽  
Heating And Cooling ◽  
Metal Sheets ◽  
Arc Current

Abstract The technology of laser-TIG welding utilizes the arc as a secondary heat source during laser welding. In TIG-leading configuration, the low-current arc precedes the beam to preheat the material. The numerical simulations representing various setups combining laser and arc were performed to study the changes of thermal cycles on the interface of thin metal sheets of overlap joint. The relations between the position of the arc towards the beam, additional heat input, and temperature gradients are discussed. The technology of laser-TIG welding of zinc-coated deep-drawing steel was experimentally applied in the same joint configuration. A good agreement between the calculated and experimental welds was achieved. The arc current less than 40 A did not cause the vaporization, neither oxidation of zinc coating on the interface surface of metal sheets. Nevertheless, the quality of laser-TIG welds was better compared to laser welds. The 40A arc current increased the heat input by about 50% and led to an almost 60% decrease in cooling rate compared to autonomous laser welding. Prolonged heating and cooling time are the key factors of improving the weld quality.

LASER WELDING OF T-BEAM FROM HETEROGENEOUS ALLOYS

2020 ◽  
Author(s):  
Сергей Вячеславович Курынцев ◽  
Андрей Владиленович Евлампьев
Keyword(s):  
Aluminum Alloy ◽  
Laser Welding ◽  
Welding Process ◽  
Lap Joint ◽  
Aluminum Alloy 5083 ◽  
Pre Treatment ◽  
T Beam ◽  
Heterogeneous Alloys ◽  
Laser Welding Process

В данной работе пересматривается процесс лазерной сварки для соединения стали 18ГСА (DH36) с алюминиевым сплавом 5083 (AA5083) из конфигурации нахлесточного соединения в тавровое, используя уже имеющиеся исследования. In this paper, the laser welding process for joining steel 18GSA (DH36) with aluminum alloy 5083 (AA5083) from the configuration of lap joint to T-joint is reviewed using existing studies. Pre-treatment of materials before welding is also considered.

On-line Nd:YAG laser welding process monitoring

1994 ◽  
Author(s):  
Marius C. Jurca ◽  
Dieter Mokler ◽  
Radu Ruican ◽  
Thomas Zeller
Keyword(s):  
Laser Welding ◽  
Process Monitoring ◽  
Nd:Yag Laser ◽  
Welding Process ◽  
On Line ◽  
Laser Welding Process

USING CLUSTERING METHODS FOR PROCESSING ACOUSTIC-EMISSION INFORMATION

2019 ◽  
pp. 12-21 ◽  
Author(s):  
L. N. Stepanova ◽  
V. V. Chernova ◽  
I. S. Ramazanov
Keyword(s):  
Cluster Analysis ◽  
Acoustic Emission ◽  
Welding Process ◽  
Clustering Methods ◽  
Advantages And Disadvantages ◽  
Informative Parameters ◽  
Rise Rate ◽  
Welding Defects ◽  
Ae Signals ◽  
Composite Samples

The analysis of the developed methods of cluster analysis of acoustic emission signals (AE), performed during the welding process and in the process of strength testing of composite samples and structures, was performed. Clustering in digital form, informative parameters of AE signals, front edge rise rate, as well as dynamic and two-stage clustering are considered. The examples of the use of the developed cluster analysis methods in the control of welding defects, composite samples and elements of aircraft structures during static and cyclic testing are shown. The advantages and disadvantages of various clustering methods for processing AE information are determined.

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