Advanced Search  
JWJ > Volume 38(4); 2020 > Article
Gaigl: MIG Arc Effects on Root Penetration of Laser Hybrid Welded T-Joints


The effects of MIG parameters on a laser hybrid process are explored in this paper. In particular, the correlation between the MIG arc length and seam parameters. Seam Parameters are the seam width and the root penetration of fillet welds on T-joints. By variation of MIG parameters, such as current, voltage, and frequency, an increase of root penetration of up to 30% is reached. Based on this data, the link between intensity of the MIG process, arc length, and root connection are worked out. The base material is made out of AlMg3Mn and the filler wire out of AlSi5.

1. Introduction

The coupling of laser and MIG processes to form a hybrid process with a single melting pool offers advantages, compared to each process individually. These advantages are characterized by high welding speed, gap bridging capability and welding depth1,2). At the same time, the low line energy leads to a reduction of thermal stress and thus to low distortion3). First trials have shown that these attributes are perfectly applicable for 3-D joining applications. In particular the joining of only a few millimeters thick sheet metal structures of cold worked aluminum alloys, which should meet high quality requirements. Pre-processing tolerances, which could cause gaps of more than one millimeter, can be compensated in the welding process. This is possible by means of position-specific increased filler material addition.
Despite some parameters, the laser hybrid process is just partially investigated. There is a lack of studies on quality parameters, such as those that influence the root connection4). This decisive parameter for the strength of the joint is adjusted through the laser power only5,6). It is even postulated that an increase in welding depth cannot be influenced by the MIG contribution7).
Studies on process parameters such as welding speed or wire feed rate are available on a large scale3,4,8,9). They have even been carried out using artificial neural networks and genetic algorithms10). These investigations were carried out on butt, lap, and flanged joints. If processes are optimized for welding depths, it is done exclusively at blind seams11,12). Investigations of T-joints are available on a very small extent and require seam preparation13), or are produced by welding through the belt plate14).
Due to these conditions, this paper analyzes the penetration of fillet welds of the T-joint. Specifically, the effect of the MIG process on the root connection is investigated.

2. Used Setup

The setup is comprised of an articulated robot and a Fronius laser hybrid welding head, with an integrated Trans Puls Synergic welding system. The laser is an YPG fiber laser YLR-5000. The laser runs in front of the MIG torch, piercing with a 5° angle and the MIG welding head follows 3 mm behind the -1 mm focal position, piercing with a 35° angle. The Welding speed is 45 mm/s, a laser power of 4.1 kW and focal diameter of 220 µm. The sheets are out of AlMg3Mn, with a thickness of 3.5 mm and the filler wire is out of AlSi5. The gap between the plates of the T-joint is 0 mm.
The temporal characteristics of voltage and current of the MIG power source were recorded using a HKS measurement system. The system consists of a Weld QAS measuring computer, the WeldAnalyst software and the P1000 process sensor. The sampling frequency was selected with 52 kHz, whereby the measurement error is ±1%.

3. Variated parameters

In order to determine the effect of the MIG arc length on the root connection AW, the arc length is varied in the following. The arc length is essentially influenced by the voltage Ueff. However, the adjustment of the voltage Ueff mandates additional parameter adaption to ensure a controlled material transfer.
If the voltage in the welding process is changed, the current also adjusts. The filler wire will be partially melted in the base current phase and detached in the pulse current phase. If the base current increases, the pulse frequency also has to be increased to prevent the arc from moving up the wire too high in the pulse current phase. An unstable arc and filler wire drop, too large for a stable process would be the consequences. In addition, if the base current increases, it may also be necessary to increase the impulse current. This raises the detaching pinch force and thus the probability for a stable filler wire drop separation. Key figures of the used parameter set are summarized in Fig. 1. These figures are clustered through the auxiliary variable arc correction LK.
Fig. 1
Process parameters of the MIG function with regards to arc correction
Fig. 2 illustrates the measured values of the arc length and arc correction LK. If the arc length is given in relation to the stickout, the resulting lengths are 35%, 40% and 45%. In the considered range of the arc correction LK, both parameters change relatively by the same amount.
Fig. 2
Photos of the arc length with regards to voltage or arc correction LK

4. Determination of seam width and MIG power

To analyze the effect of the arc correction LK to weld seam properties, this was varied from LK = -15% to LK = -1%. Other process parameters are invariant. Cross sections of the weldings are presented in Fig. 3. These cross sections show with decreasing arc correction LK an undercut on the weld seam surface evolving and increasing in size. Also the melt spill out at the weld root increases with decreasing arc correction LK. This indicates a greater root connection AW. This change represents also a decline in quality. However, this paper aims to provide a basic understanding of the interaction between MIG arc parameters and the root connection. This understanding should be used in comparable applications to optimize the weld seam quality regarding the assurance of the root connection.
Fig. 3
Cross sections with seam width bSeam in regards to the arc correction LK
For further investigations the seam width bSeam and root connection AW were measured on the cross sections of Fig. 3 and on additional samples. With increasing arc correction LK, respectively the voltage, the seam width bSeam and MIG power PMIG increase too, as shown in Fig. 4. For a more profound understanding of the influence of these parameters on the root connection AW, they will have to be related with the intensity of the MIG arc.
Fig. 4
Seam width bSeam and power PMIG plotted over the arc correction LK

5. Intensity of the MIG arc and the root connection of the T-joint

If an even distribution and circular intensity of the MIG arc is presumed, the arc intensity IArc can be determined by means of the MIG power PMIG and the seam width bSeam. This approximation is summarized in equation (1).
With the thermal efficiency ηth of the MIG process assumed to be 90%, the calculated intensity IArc is plotted over the arc correction LK, as shown in Fig. 5. With decreasing arc correction LK, the intensity IArc and the root connection AW rise. The rise of both functions is not linear. Even though the parameter adjustment of the arc correction LK lead to linear changes in seam width bSeam and MIG power PMIG. The reasons for the non-linearity is the quadratic consideration of the seam width bSeam in equation (1).
Fig. 5
Correlation of the intensity IArc and the output variable root connection AW
The causal relationship between the functions is the change in heat flow. The increase of the intensity IArc leads to changes in heat transfer and the melting behavior. These changes in heat conduction influence the root connection AW and the melt emerging at the weld root.
The scattering of the data points in Fig. 5 is high, which can be traced back to the process. For example, the determined measured values of the arc correction LK = -11% have to be considered (see arrows in Fig. 5). Three measured values with high intensities IArc correlate with high root connection AW. The same applies to two measured values with low intensities IArc and low root connection AW.
Nonetheless, these results show that an increase of the root connection AW of approximately 1.1 mm (+30%) can be achieved in the considered area of the arc correction LK. This is done exclusively by adjusting the MIG parameters of the laser hybrid process.


1. Kah P, Salminen A, Martikainen J. The influence of parameters on penetration, speed and bridging in laser hybrid welding, Mechanika. University of Technology; Finland: (2011)

2. Kah P, Salminen A, Martikainen J. Laser-arc hybrid welding processes (Review). The Paton Weld. J. 6. (2010)

3. Sommitsch C, Posch G, Weinberger T, Figner G, höherer Prozesssicherheit Neue Fügetechniken mit, Monatshefte Bergund Hüttenmännische. Springer Verlag. Berlin, Germany: (2010)

4. Bunaziv I, Akselsen O. M, Salminen A, Unt A. Fiber laser-MIG hybrid welding of 5 mm 5083 aluminum alloy. J. Mater. Process. Technol. 233 (2016)
5. Steen W. M. Arc augmented laser processing of materials. J. Appl. Phys. 51 (1980)
6. Bagger C, Olsen F. O. Review of laser hybrid welding. J. Laser Appl. 17 (2005)
7. Reich F, Aluminium- legierungen Laser-MIG-Hybridschweißen von. Aktuelle Informationen aus dem Institut für Schweißtechnik und Fügetechnik der RWTH Aachen ISF Direkt 31, Freundeskreis des Instituts für Schwei- ßtechnik e.V. RWTH Aachen. Germany: (2005)

8. Ji J. Prozessporen beim Nd:YAG-Laserstrahl-MSG- Hybridschweißen von Aluminiumlegierungen - Teil 2:Strategie zu ihrer Vermeidung. Schweißen und Schneiden 59 Heft. 10 (2007)

9. Acherjee B. Laser Arc Hybrid Welding. Advances in Laser Materials Processing. Second. Chapter 9 (2018)
10. Chaki1 S, Ghosal S. A GA–ANN hybrid model for prediction and optimization of CO2 laser-MIG Hybrid welding process. Int. J. Automotive Mech. Eng. (IJAME). (2015)

11. Walz C, Seefeld T, Sepold G. Nahtgeometrie und Proze-ßstabilität beim Laser-MIG-Schweißen. Laser Opto. 33 (H.2) (2001), 64–67

12. Bidi L, Mattei S, Cicala E, Andrzejewski H, Le Masson P, Schroeder J. The use of exploratory experimental designs combined with thermal numerical modelling to obtain a predictive tool for hybrid laser/MIG welding and coating processes. Opt. Laser Technol. 43 (2011), 537–545
13. Nilsson K, Engström H, Kaplan A. Influence of butt- and T-joint preparation in laser arc hybrid welding. International Institute of Welding. Copenhagen, Denmark: (2002), Doc. XIIp. 1732–02

14. Li C, Liu L. Investigation on weldability of magnesium alloy thin sheet T-joints:arc welding, laser welding, and laser-arc hybrid welding. Int. J. Adv. Manuf. Technol. 65 (1-4) (2013)

PDF Links  PDF Links
PubReader  PubReader
ePub Link  ePub Link
Full text via DOI  Full text via DOI
Download Citation  Download Citation
CrossRef TDM  CrossRef TDM
Related articles
Recent Technological Tendency of Laser/Arc Hybrid Welding  2013 April;31(2)
Effects of Welding Parameters on Penetration Depth in CO₂ Laser-GMA Hybrid Welding  2004 February;22(1)
A Study on the Prediction of Deformations of Welded Structures   1997 October;15(5)
A Study on the Optimization of Shape of Weld Joints   1997 August;15(4)
Effect of Metal Transfer Mode on Spatter Generation of CO2 Welding   1997 April;15(2)
Recent Technological Tendency of Laser/Arc Hybrid Welding  2013 April;31(2)
Effects of Welding Parameters on Penetration Depth in CO₂ Laser-GMA Hybrid Welding  2004 February;22(1)
A Study on the Prediction of Deformations of Welded Structures   1997 October;15(5)
A Study on the Optimization of Shape of Weld Joints   1997 August;15(4)
Effect of Metal Transfer Mode on Spatter Generation of CO2 Welding   1997 April;15(2)
Register for e-submission
Register here to access the e-submission system of Journal of Welding and Joining for authors and reviewers.
Manuscript Submission
To submit a manuscript, please visit the Journal of Welding and Joining e-submission management system at, read the Instructions for Authors, and log into the Journal of Welding and Joining e-submission system. For assistance with manuscript submission, please contact:
Free archive
Anyone may access any past or current articles without logging in.
Editorial Office
#304, San-Jeong Building,
23, Gukhoe-daero 66-gil, Yeongdeungpo-gu, Seoul 07237, Korea
TEL : +82-2-538-6511    FAX : +82-2-538-6510   E-mail:
Browse Articles |  Current Issue |  For Authors and Reviewers |  About
Copyright© by The Korean Welding and Joining Society. All right reserved.