Change search
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Metal fusion using pulsed GasMetal Arc: Melt pool modellingand CFD simulation
University West, Department of Engineering Science, Division of Welding Technology. (KAMPT)ORCID iD: 0000-0002-9692-2506
2023 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Pulsed gas metal arc is a highly efficient technique used in manufacturing processes like welding and additive manufacturing. It offers high productivity and cost benefits but it is also prone to defect formation when process parameters are not properly controlled and optimized. A deeper process understanding can support achieving improved process control and mitigate these potential drawbacks. Nevertheless, there are still several challenges. For instance, the correlation between the input and output process parameters is non-linear and complex due to the multi-physics nature of the process. In addition, the elevated temperature and the intense radiative emission from the arc, along with the smoke, and the non-transparency of metal, make in-process observation challenging. Modelling and simulation offer a complementary approach to gain a deeper process understanding. In this study, a thermo- and fluid dynamics model was developed, focusing on the melt pool and metal deposition, while simplifying the arc to boundary conditions (decoupled approach). This model incorporates various forces and phenomena such as thermocapillary and electromagnetic forces, melting and solidification, and tracking of surface deformation and droplet coalescence.

In the first part of the thesis, the developed model was applied to investigate the effect of workpiece orientations on the melt pool dynamics and reinforced bead geometry in multi-layer gas metal arc welding of a V-groove joint. The comparison of the predicted fusion zone with macrographs obtained from the experiments showed good qualitative agreement. It was found that the force balance in the melt pool changes significantly when changing the workpiece orientation by as little as 20◦ relative to the flat position. This results in distinct melt flow patterns, melt pool shapes, bead geometries, and in some cases, defect formation such as humping, undercut, and insufficient fusion. It was concluded that to avoid these defects a lower angle range is necessary for multilayer welding with the uphill orientation and side inclination.

The second part of the thesis focused on analyzing different variants of the model for the electromagnetic force with a decoupled approach. Three commonly used models were compared: (1) the analytical models proposed by Kou and Sun inintegral form, (2) by Tsao and Wu in algebraic form, and (3) the partial differential equations governing the electric and magnetic fields. The comparative investigation was supported by experimental tests that also provided estimates of unknown model parameters and validation data. It was found that the distinct assumptions on which these models rely are not all justified. They resulted inpredicting different melt flow patterns and amplitude of the free surface oscillations, as well as different melt pool shapes and bead geometries. Model (3) is recommended to advance to a predictive melt pool model and was subsequentlyused in the remaining work of the thesis.

Furthermore, the literature shows that modeling the effect of pulsed arc on the melt pool using a decoupled approach involves various simplifications. Arc pulsation affects energy and force balance in the melt pool through arc heat flux, arc pressure, and electromagnetic force. A systematic investigation of model variants considering pulsing was conducted using previously documented experimental test cases. The results showed that the influence of arc pressure was insignificant in those cases. However, model variants simplifying arc pulsing to a time-averaged effect underestimated the amplitude of the Marangoni flow and downward flow compared to a more comprehensive approach that considered the time dependence of arc pulsation. Thus, it is recommended to use a meltpool model that accounts for the time-dependent arc pulsation, which was also subsequently utilized in the remaining work of the thesis.

The electromagnetic force models discussed earlier assume a stationary free surface when computing the electromagnetic force. However, this force is often at leading order in the vicinity of the arc. In the same region, the metal drop transfer leads to a periodic deformation of the melt pool free surface. In the final part of the thesis, the model was extended to account for free surface deformation when computing the electromagnetic force. This extension was applied to experimental test cases, and a comparison was made with simulation results obtained using the stationary electromagnetic force model. Significant differences in the results were observed, particularly in predicting the experimentally observed fingertip-shaped fusion zone geometry. The proposed improvement in the electromagnetic force model provided better predictions in this regard.

Abstract [sv]

Gasmetallbågsprocessen har revolutionerat metallbearbetning och produktionsteknik under ett århundrade med sin påfallande effektivitet och mångsidighet, speciellt vid svetsning. På senare år har denna teknik också tillämpats alltmer inom additiv tillverkning (AM), även känt som 3D-printing. Gasmetallbågsbaserad AM har väckt ett stort industriellt intresse på grund av dess förmåga att tillverka stora och komplexa komponenter. Det finns dock problem, dels kring defekter i processen, dels kring numeriska modellers förmåga att simulera processen. Följaktligen finns det ett behov av en djupare förståelse och förbättrade modeller för att övervinna dessa utmaningar och frigöra den fulla potentialen i denna teknologi. För att angripa detta problem utvecklades och tillämpades modellering med hjälp strömningsmekaniska beräkningar (CFD) i detta avhandlingsarbete, tillsammans med fysiska experiment för att komplettera modelleringsarbetet. Det utförda modelleringsarbetet har gjort det möjligt att förklara hur flödet i smältan och dess geometri orsakar defekter vid ändringar av ett arbetsstyckesorientering så lite som 20◦ jämfört med horisontell positionering vid svets iV-fog. Dessutom använder moderna numeriska modeller för smältans fysikolika delmodeller för att beräkna den elektromagnetiska kraften och tidsberoendet hos en pulserande ljusbåge. Dessa delmodeller jämförandes i en analys föratt förklara deras signifikanta skillnader vid simulering av smältflödet, termisk konvektion, ytvågor, smältans form och stelnade geometri. De föreslagna förbättringarna i modelleringen baserat på denna analys har gett mer noggranna förutsägelser av processens smältzon, vilket bidrar till utvecklingen av en sant prediktiv simuleringsmodell som kommer att vara användbar i den efterfrågade utvecklingen av gasmetallbågsprocessen.

Place, publisher, year, edition, pages
Trollhättan: University West , 2023. , p. 112
Series
PhD Thesis: University West ; 56
Keywords [en]
Gas metal arc, Electromagnetic force modelling, Free surface deformation, Computational Fluid Dynamics, OpenFOAM
Keywords [sv]
Gasmetallbågsvetsning, Svetsläge, Elektromagnetiskkraftmodellering, Smältytans rörelser, Computational Fluid Dynamics, OpenFOAM
National Category
Manufacturing, Surface and Joining Technology
Research subject
Production Technology
Identifiers
URN: urn:nbn:se:hv:diva-20642ISBN: 978-91-89325-46-3 (print)ISBN: 978-91-89325-46-3 (electronic)OAI: oai:DiVA.org:hv-20642DiVA, id: diva2:1793258
Public defence
2023-10-03, C118, Trollhättan, 10:00 (English)
Opponent
Supervisors
Note

Paper I is an Open Access article.

Submitted articles are not included in the electronic thesis.

Available from: 2023-09-12 Created: 2023-08-31 Last updated: 2024-01-10Bibliographically approved
List of papers
1. Comparative study of the main electromagnetic models applied to melt pool prediction with gas metal arc: Effect on flow, ripples from drop impact, and geometry
Open this publication in new window or tab >>Comparative study of the main electromagnetic models applied to melt pool prediction with gas metal arc: Effect on flow, ripples from drop impact, and geometry
2022 (English)In: International Journal of Heat and Mass Transfer, ISSN 0017-9310, E-ISSN 1879-2189, Vol. 194, article id 123068Article in journal (Refereed) Published
Abstract [en]

The present work concerns the electromagnetic force models in computational fluid dynamics simulations of melt pools produced with electric arcs. These are commonly applied to gas metal arcs with metal transfer, in welding and additive manufacturing. Metal drop impact on the melt pool is thus included in this study. The electromagnetic force models applied in literature use either numerical solutions of Poisson equations or one of the two analytical models developed by Kou and Sun, or Tsao and Wu. These models rely on assumptions for which the effect on the melt pool predictions remains to be understood. The present work thoroughly investigates those assumptions and their effects. It has been supported by dedicated experimental tests that did provide estimates of unknown model parameters and validation data. The obtained results show that the assumptions that fundamentally distinguish these three models change the electromagnetic force, including the relation between its components. These changes, which can also be spatially non-uniform, are large. As a result, these models lead to significantly different recirculation flow pattern, thermal convection, melt pool morphology, bead dimensions, and free surface response to the metal transfer. We conclude by proposing conditions in which each of these models is suited or questionable.

Place, publisher, year, edition, pages
Elsevier, 2022
Keywords
Maxwell electromagnetic force model, Kou and Sun model, Tsao and Wu model, Metal transfer, Molten pool, Free surface oscillation, Gas metal arc
National Category
Manufacturing, Surface and Joining Technology
Research subject
Production Technology
Identifiers
urn:nbn:se:hv:diva-19030 (URN)10.1016/j.ijheatmasstransfer.2022.123068 (DOI)001125861400004 ()2-s2.0-85131103929 (Scopus ID)
Funder
European CommissionEU, Horizon Europe
Note

CC BY-NC-ND license

Available from: 2022-08-10 Created: 2022-08-10 Last updated: 2024-04-12Bibliographically approved
2. Effect of Substrate Orientation on Melt Pool during Multi-Layer Deposition in V-Groove with Gas Metal Arc
Open this publication in new window or tab >>Effect of Substrate Orientation on Melt Pool during Multi-Layer Deposition in V-Groove with Gas Metal Arc
Show others...
2021 (English)In: Proceedings of the 7th World Congress on Mechanical, Chemical, and Material Engineering (MCM'21) / [ed] Huihe Qiu, 2021, article id HTFF 130Conference paper, Published paper (Refereed)
Abstract [en]

Thermo-fluid dynamic and experimental approaches are used to investigate the influence of 20° uphill, downhill and sideway substrate orientation during metal deposition over a previously deposited bead in a V-groove. The computational fluid dynamic model with free surface deformation and metal transfer gives insight into the melt pool flow and causes of defect formation observed on the solidified beads. The experimental metallographs, high-speed images and computational results show good agreement. It is found that the deposition of a second layer on a smooth first layer cooled down to room temperature leads to large changes in melt pool flow patternat 20° substrate inclination compared to flat condition. It results in undercut and humps with the uphill orientation and undercut with the side inclination. Therefore, lower angle range is necessary for multilayer gas metal arc deposition for these two last configurations.

Keywords
metal deposition, gas metal arc welding, V-groove, substrate orientation, melt flow, reinforced bead, hump, OpenFOAM
National Category
Manufacturing, Surface and Joining Technology
Research subject
Production Technology
Identifiers
urn:nbn:se:hv:diva-17668 (URN)10.11159/htff21.130 (DOI)978-1-927877-93-7 (ISBN)
Conference
7th World Congress on Mechanical, Chemical, and Material Engineering (MCM'21)
Funder
EU, Horizon 2020, INTEGRADDESwedish National Infrastructure for Computing (SNIC)
Available from: 2021-11-01 Created: 2021-11-01 Last updated: 2023-08-31Bibliographically approved

Open Access in DiVA

Avhandlingen(10970 kB)201 downloads
File information
File name FULLTEXT02.pdfFile size 10970 kBChecksum SHA-512
a83031ac86ce99db9c26fecbb0bafc8019db1b91de16e0ecb51967484abebe2ff8684e78b4a76c7cf517abcc16d8136e34b1a7dc050af317b6f59152f07ed823
Type fulltextMimetype application/pdf
Spikbladet(94 kB)44 downloads
File information
File name SPIKBLAD01.pdfFile size 94 kBChecksum SHA-512
bf6dace6796f424bf8e7c2a62296ffcaf8c06c2fec095f9ffdebcca9cc6277a73f6846b60f72fa2ddbbb622de4c0006e140e918716adf87b222391c2dfdcfb66
Type spikbladMimetype application/pdf

Authority records

Aryal, Pradip

Search in DiVA

By author/editor
Aryal, Pradip
By organisation
Division of Welding Technology
Manufacturing, Surface and Joining Technology

Search outside of DiVA

GoogleGoogle Scholar
Total: 204 downloads
The number of downloads is the sum of all downloads of full texts. It may include eg previous versions that are now no longer available

isbn
urn-nbn

Altmetric score

isbn
urn-nbn
Total: 621 hits
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf