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  <doc>
    <id>56532</id>
    <completedYear/>
    <publishedYear>2022</publishedYear>
    <thesisYearAccepted/>
    <language>eng</language>
    <pageFirst>1</pageFirst>
    <pageLast/>
    <pageNumber/>
    <edition/>
    <issue/>
    <volume/>
    <type>conferenceobject</type>
    <publisherName/>
    <publisherPlace/>
    <creatingCorporation/>
    <contributingCorporation/>
    <belongsToBibliography>0</belongsToBibliography>
    <completedDate>--</completedDate>
    <publishedDate>--</publishedDate>
    <thesisDateAccepted>--</thesisDateAccepted>
    <title language="eng">Evaluation of narrowed weld pool shapes and their effect on resulting potential defects during deep penetration laser beam welding</title>
    <abstract language="eng">This study presents mechanisms of the evolution of a narrowed region in the weld pool center during deep penetration laser beam welding. In numerous numerical studies presented in this study, it was also found that the local reduction of the weld pool size can cause detrimental effects on the melt flow behavior and the resulting properties of the welds. A particularly large influence of this effect was identified in three aspects. Firstly, the local variation of the solidification sequence of the weld pool causes an increase in the hot-cracking susceptibility due to a locally delayed solidification. Secondly, it was proven that a change in the local length and width of the weld pool is associated with an adverse impact on the potential flow routes of the molten material that induces stronger local variations of its solidification. Thus, the element mixing, e.g. during the welding with filler materials, is blocked. This leads to a non-homogeneous chemical composition of the final weld and can cause undesired effects on the final material properties. Finally, another observed effect is related to the reduced ability of process pores to reach the top surface. As this type of porosity is usually produced around the keyhole tip, the change of the fluid flow regime above this area plays a significant role in determining the final path of the pores until the premature solidification in the middle of the weld pool captures them. This study summarizes mainly numerical results which were supported by selected experimental validation results.</abstract>
    <parentTitle language="eng">Proceedings of the ICALEO 2022, 41st International Congress on Applications of Lasers &amp; Electro-Optics</parentTitle>
    <enrichment key="eventName">International Congress of Applications of Lasers &amp; Electro-Optics 2022</enrichment>
    <enrichment key="eventPlace">Orlando, FL, USA</enrichment>
    <enrichment key="eventStart">17.10.2022</enrichment>
    <enrichment key="eventEnd">20.10.2022</enrichment>
    <enrichment key="opus.source">publish</enrichment>
    <author>Marcel Bachmann</author>
    <author>Xiangmeng Meng</author>
    <author>Antoni Artinov</author>
    <author>Michael Rethmeier</author>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Weld pool shape</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Laser beam welding</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Solidification</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Porosity</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Numerical process simulation</value>
    </subject>
    <collection role="ddc" number="620">Ingenieurwissenschaften und zugeordnete Tätigkeiten</collection>
    <collection role="institutes" number="">9 Komponentensicherheit</collection>
    <collection role="institutes" number="">9.3 Schweißtechnische Fertigungsverfahren</collection>
    <collection role="themenfelder" number="">Material</collection>
    <collection role="fulltextaccess" number="">Datei im Netzwerk der BAM verfügbar ("Closed Access")</collection>
    <collection role="literaturgattung" number="">Graue Literatur</collection>
  </doc>
  <doc>
    <id>55775</id>
    <completedYear/>
    <publishedYear>2022</publishedYear>
    <thesisYearAccepted/>
    <language>eng</language>
    <pageFirst>1</pageFirst>
    <pageLast>7</pageLast>
    <pageNumber/>
    <edition/>
    <issue>4</issue>
    <volume>34</volume>
    <type>article</type>
    <publisherName>Laser Institute of America</publisherName>
    <publisherPlace>Orlando, Fla.</publisherPlace>
    <creatingCorporation/>
    <contributingCorporation/>
    <belongsToBibliography>1</belongsToBibliography>
    <completedDate>--</completedDate>
    <publishedDate>--</publishedDate>
    <thesisDateAccepted>--</thesisDateAccepted>
    <title language="eng">Evaluation of narrowed weld pool shapes and their effect on resulting potential defects during deep penetration laser beam welding</title>
    <abstract language="eng">This study presents mechanisms of the evolution of a narrowed region in the weld pool center during deep penetration laser beam welding. In numerous numerical studies presented in this study, it was also found that the local reduction of the weld pool size can cause detrimental effects on the melt flow behavior and the resulting properties of the welds. A particularly large influence of this effect was identified in three aspects. First, the local variation of the solidification sequence of the weld pool causes an increase in the hot-cracking susceptibility due to a locally delayed solidification. Second, it was proven that a change in the local length and width of the weld pool is associated with an adverse impact on the potential flow routes of the molten material that induces stronger local variations of its solidification. Thus, the element mixing, e.g., during the welding with filler materials, is blocked. This leads to a non-homogeneous chemical composition of the final weld and can cause undesired effects on the final material properties. Finally, another observed effect is related to the reduced ability of process pores to reach the top surface. As this type of porosity is usually produced around the keyhole tip, the change of the fluid flow regime above this area plays a significant role in determining the final path of the pores until the premature solidification in the middle of the weld pool captures them. This study summarizes mainly numerical results that were supported by selected experimental validation results.</abstract>
    <parentTitle language="eng">Journal of Laser Applications</parentTitle>
    <identifier type="doi">10.2351/7.0000733</identifier>
    <identifier type="urn">urn:nbn:de:kobv:b43-557759</identifier>
    <identifier type="issn">1042-346X</identifier>
    <enrichment key="opus.source">publish</enrichment>
    <enrichment key="date_peer_review">07.11.2022</enrichment>
    <licence>Creative Commons - CC BY - Namensnennung 4.0 International</licence>
    <author>Marcel Bachmann</author>
    <author>Xiangmeng Meng</author>
    <author>Antoni Artinov</author>
    <author>Michael Rethmeier</author>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Weld pool shape</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Laser beam welding</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Solidification</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Porosity</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Numerical process simulation</value>
    </subject>
    <collection role="ddc" number="620">Ingenieurwissenschaften und zugeordnete Tätigkeiten</collection>
    <collection role="institutes" number="">9 Komponentensicherheit</collection>
    <collection role="institutes" number="">9.3 Schweißtechnische Fertigungsverfahren</collection>
    <collection role="themenfelder" number="">Material</collection>
    <collection role="themenfelder" number="">Degradationsmechanismen</collection>
    <collection role="literaturgattung" number="">Verlagsliteratur</collection>
    <collection role="fulltextaccess" number="">Datei für die Öffentlichkeit verfügbar ("Open Access")</collection>
    <collection role="unnumberedseries" number="">Wissenschaftliche Artikel der BAM</collection>
    <thesisPublisher>Bundesanstalt für Materialforschung und -prüfung (BAM)</thesisPublisher>
    <file>https://opus4.kobv.de/opus4-bam/files/55775/Bachmann_JLA2022.pdf</file>
  </doc>
  <doc>
    <id>45875</id>
    <completedYear/>
    <publishedYear>2018</publishedYear>
    <thesisYearAccepted/>
    <language>eng</language>
    <pageFirst>683</pageFirst>
    <pageLast>686</pageLast>
    <pageNumber/>
    <edition/>
    <issue/>
    <volume>74</volume>
    <type>article</type>
    <publisherName>Elsevier Ltd.</publisherName>
    <publisherPlace>Amsterdam [u.a.]</publisherPlace>
    <creatingCorporation/>
    <contributingCorporation/>
    <belongsToBibliography>0</belongsToBibliography>
    <completedDate>--</completedDate>
    <publishedDate>--</publishedDate>
    <thesisDateAccepted>--</thesisDateAccepted>
    <title language="eng">Weld pool shape observation in high power laser beam welding</title>
    <abstract language="eng">The geometry of the melt pool in laser beam welding plays a major role to understand the dynamics of the melt and its solidification behavior. In this study, a butt configuration of 15 mm thick structural steel and transparent quartz glass was used to observe the weld pool geometry by means of high-speed camera and an infrared camera recording. The observations show that the dimensions of the weld pool vary depending on the depth. The areas close to the weld pool surface take a teardrop-shape. A bulge-region and its temporal evolution were observed approximately in the middle of the depth of the weld pool. Additionally, a 3D transient thermal-fluid numerical simulation was performed to obtain the weld pool shape and to understand the formation mechanism of the observed bulging effect. The model takes into account the local temperature field, the effects of phase transition, thermo-capillary convection, natural convection and temperature-dependent material properties up to evaporation temperature. The numerical results showed good accordance and were furthermore used to improve the understanding of the experimentally observed bulging effect.</abstract>
    <parentTitle language="eng">Procedia CIRP</parentTitle>
    <identifier type="doi">10.1016/j.procir.2018.08.043</identifier>
    <identifier type="issn">2212-8271</identifier>
    <identifier type="urn">urn:nbn:de:kobv:b43-458759</identifier>
    <enrichment key="eventName">LANE Conference 2018</enrichment>
    <enrichment key="eventPlace">Fürth, Germany</enrichment>
    <enrichment key="eventStart">03.09.2018</enrichment>
    <enrichment key="eventEnd">06.09.2018</enrichment>
    <licence>Creative Commons - CC BY-NC-ND - Namensnennung - Nicht kommerziell - Keine Bearbeitungen 4.0 International</licence>
    <author>Antoni Artinov</author>
    <author>Nasim Bakir</author>
    <author>Marcel Bachmann</author>
    <author>Andrey Gumenyuk</author>
    <author>Michael Rethmeier</author>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>High power laser beam welding</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Weld pool shape</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Bulging</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Numerical process simulation</value>
    </subject>
    <collection role="ddc" number="620">Ingenieurwissenschaften und zugeordnete Tätigkeiten</collection>
    <collection role="literaturgattung" number="">Verlagsliteratur</collection>
    <collection role="fulltextaccess" number="">Datei für die Öffentlichkeit verfügbar ("Open Access")</collection>
    <collection role="unnumberedseries" number="">Wissenschaftliche Artikel der BAM</collection>
    <thesisPublisher>Bundesanstalt für Materialforschung und -prüfung (BAM)</thesisPublisher>
    <file>https://opus4.kobv.de/opus4-bam/files/45875/Weld_pool_observation.pdf</file>
  </doc>
  <doc>
    <id>56995</id>
    <completedYear/>
    <publishedYear>2022</publishedYear>
    <thesisYearAccepted/>
    <language>eng</language>
    <pageFirst>28</pageFirst>
    <pageLast>29</pageLast>
    <pageNumber/>
    <edition/>
    <issue>57</issue>
    <volume/>
    <type>article</type>
    <publisherName>Europa Science</publisherName>
    <publisherPlace>Cambridge, UK</publisherPlace>
    <creatingCorporation/>
    <contributingCorporation/>
    <belongsToBibliography>0</belongsToBibliography>
    <completedDate>--</completedDate>
    <publishedDate>--</publishedDate>
    <thesisDateAccepted>--</thesisDateAccepted>
    <title language="eng">Investigating defects caused by narrow pool shapes in deep penetration welding</title>
    <abstract language="eng">Laser beam welding is a widely used joining technique in many industrial applications. This is mainly due to its many unique advantages, especially compared to conventional arc welding processes. These advantages include, among others, highly concentrated energy deposition, low total heat input and a capacity to penetrate deep into the material while causing only small welding distortions. &#13;
However, at the same time, the small dimension of the laser spot, high solidification rates, and small dimensions of the weld pool itself can provoke issues regarding the assembly tolerances of the workpiece, the hot-cracking phenomena, as well as keyhole-induced bubbles escaping from the melt. &#13;
Weld pool shapes in laser beam welding are elongated at the external, free surfaces under the action of the main driving forces in the melt – such as recoil pressure and surface tension forces – while being shorter in the internal areas of the weld pool. This leads to a regular solidification sequence from the internal zones toward the free surfaces, e.g. from the bottom to the top in partial penetration welding. However, in recent studies  reported in the literature and seen in the experimental and numerical investigations of BAM Bundesanstalt für Materialforschung und -prüfung in Berlin, it was found that an internal narrowing phenomenon can occur that is often accompanied by a distinct bulging of the weld bead in deeper zones.&#13;
As the internal behaviour of the melt during the process is hardly optically accessible, several numerical models and experimental techniques were established to visualise the mechanisms of the formation of the bulging and the narrowing phenomenon and to reveal the consequences on the solidification sequence, pore formation, and filler metal dilution.</abstract>
    <parentTitle language="eng">Laser Systems Europe</parentTitle>
    <identifier type="issn">1759-0752</identifier>
    <enrichment key="opus.source">publish</enrichment>
    <author>Marcel Bachmann</author>
    <author>Xiangmeng Meng</author>
    <author>Antoni Artinov</author>
    <author>Michael Rethmeier</author>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Weld pool shape</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Laser beam welding</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Solidification</value>
    </subject>
    <collection role="ddc" number="620">Ingenieurwissenschaften und zugeordnete Tätigkeiten</collection>
    <collection role="institutes" number="">9 Komponentensicherheit</collection>
    <collection role="institutes" number="">9.3 Schweißtechnische Fertigungsverfahren</collection>
    <collection role="themenfelder" number="">Material</collection>
    <collection role="fulltextaccess" number="">Datei im Netzwerk der BAM verfügbar ("Closed Access")</collection>
    <collection role="literaturgattung" number="">Graue Literatur</collection>
  </doc>
  <doc>
    <id>58803</id>
    <completedYear/>
    <publishedYear>2023</publishedYear>
    <thesisYearAccepted/>
    <language>eng</language>
    <pageFirst>161</pageFirst>
    <pageLast>188</pageLast>
    <pageNumber/>
    <edition/>
    <issue/>
    <volume>13</volume>
    <type>conferenceobject</type>
    <publisherName>Verlag der Technischen Universität Graz</publisherName>
    <publisherPlace/>
    <creatingCorporation>Technische Universität Graz</creatingCorporation>
    <contributingCorporation/>
    <belongsToBibliography>0</belongsToBibliography>
    <completedDate>--</completedDate>
    <publishedDate>--</publishedDate>
    <thesisDateAccepted>--</thesisDateAccepted>
    <title language="eng">Numerical analysis of the dependency of the weld pool shape on turbulence and thermodynamic activity of solutes in laser beam welding of unalloyed steels</title>
    <abstract language="eng">A three-dimensional numerical model was developed to accurately predict the steady-state weld pool shape in full penetration laser beam welding. The model accounts for the coupling between the heat transfer and the fluid dynamics by considering the effects of solid/liquid phase transition, thermo-capillary convection, natural convection, and phase-specific and temperature-dependent material properties up to the evaporation temperature. A fixed right circular cone was utilized as a keyhole geometry to consider the heat absorbed from the laser beam. The model was used to analyze the influence of the thermodynamic activity of solutes and turbulence on the weld pool shape. A mesh sensitivity analysis was performed on a hybrid mesh combining hexahedral and tetrahedral elements. For the case of full penetration laser beam welding of 8 mm thick unalloyed steel sheets, the dependence of the weld pool shape on the surface-active element sulfur was found to be negligible. The analysis of the results showed that a laminar formulation is sufficient for accurately predicting the weld pool shape since the turbulence has a minor impact on the flow dynamics in the weld pool. The validity of the numerical results was backed up by experimental measurements and observations, including weld pool length, local temperature history, and a range of metallographic crosssections.</abstract>
    <parentTitle language="eng">Mathematical Modelling of Weld Phenomena 13</parentTitle>
    <identifier type="issn">2410-0544</identifier>
    <identifier type="isbn">978-3-85125-968-1</identifier>
    <identifier type="isbn">978-3-85125-969-8</identifier>
    <enrichment key="eventName">13th International Seminar Numerical Analysis of Weldability</enrichment>
    <enrichment key="eventPlace">Seggau, Austria</enrichment>
    <enrichment key="eventStart">04.09.2022</enrichment>
    <enrichment key="eventEnd">07.09.2022</enrichment>
    <enrichment key="opus.source">publish</enrichment>
    <enrichment key="opus.doi.autoCreate">false</enrichment>
    <enrichment key="opus.urn.autoCreate">true</enrichment>
    <author>Antoni Artinov</author>
    <author>Pascal Kising</author>
    <author>Marcel Bachmann</author>
    <author>Xiangmeng Meng</author>
    <author>Michael Rethmeier</author>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Weld pool shape</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Numerical modeling</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Laser beam welding</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Thermo-capillary convection</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Turbulence</value>
    </subject>
    <collection role="ddc" number="620">Ingenieurwissenschaften und zugeordnete Tätigkeiten</collection>
    <collection role="institutes" number="">9 Komponentensicherheit</collection>
    <collection role="institutes" number="">9.3 Schweißtechnische Fertigungsverfahren</collection>
    <collection role="themenfelder" number="">Material</collection>
    <collection role="themenfelder" number="">Degradationsmechanismen</collection>
    <collection role="fulltextaccess" number="">Datei im Netzwerk der BAM verfügbar ("Closed Access")</collection>
    <collection role="literaturgattung" number="">Graue Literatur</collection>
  </doc>
  <doc>
    <id>49344</id>
    <completedYear/>
    <publishedYear>2019</publishedYear>
    <thesisYearAccepted/>
    <language>eng</language>
    <pageFirst>1</pageFirst>
    <pageLast>8</pageLast>
    <pageNumber/>
    <edition/>
    <issue/>
    <volume/>
    <type>conferenceobject</type>
    <publisherName/>
    <publisherPlace/>
    <creatingCorporation>Laser Institute of America (LIA)</creatingCorporation>
    <contributingCorporation/>
    <belongsToBibliography>0</belongsToBibliography>
    <completedDate>--</completedDate>
    <publishedDate>--</publishedDate>
    <thesisDateAccepted>--</thesisDateAccepted>
    <title language="eng">Mathematical modeling of the geometrical differences between the weld end crater and the steady-state weld pool</title>
    <abstract language="eng">The geometrical characteristics of the weld end crater are commonly used for the validation of numerical results in welding simulation. A semi-analytical model calculating the cooling stage of the welding process after the moving energy source is turned off has been developed. A solution for various combinations of heat sources and workpieces has been found. The theoretical limits for the heat transfer of the absorbed energy during cooling in a thin plate and a semi-infinite body were studied. It is shown that after turning off the energy source, an additional melting of the base material in longitudinal direction may occur. The developed technique is applied to complete-penetration keyhole laser beam welding of a 2 mm thick austenitic chromium-nickel 316L steel plate at a welding speed of 20 mm/s and a laser power of 2.3 kW. The results show a theoretical increase of the weld end crater length in comparison to the length of the steady-state weld pool of up to 19 %. A shift of the centre of the end crater, in which the solidification of the liquid metal ends, towards the tail of the end crater relative to the axis of the heat source at the time of its termination, was computed. The speed and the direction of crystallization of the molten material in the weld pool and the end crater were found to be different. A good agreement between the computational results and the welding experiments was achieved.</abstract>
    <parentTitle language="eng">ICALEO 2019 - The International Congress on Applications of Lasers &amp; Electro-Optics (Proceedings)</parentTitle>
    <identifier type="isbn">978-1-940168-1-42</identifier>
    <identifier type="url">http://icaleo.conferencespot.org/2019-proceedings?qr=1</identifier>
    <enrichment key="eventName">ICALEO 2019 - The International Congress on Applications of Lasers &amp; Electro-Optics (Proceedings)</enrichment>
    <enrichment key="eventPlace">Orlando, FL USA</enrichment>
    <enrichment key="eventStart">07.10.2019</enrichment>
    <enrichment key="eventEnd">10.10.2019</enrichment>
    <enrichment key="opus.doi.autoCreate">false</enrichment>
    <enrichment key="opus.urn.autoCreate">true</enrichment>
    <author>Antoni Artinov</author>
    <author>V. Karkhin</author>
    <author>Marcel Bachmann</author>
    <author>Michael Rethmeier</author>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Keyhole mode welding</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Weld pool shape</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>End-crater</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Heat conduction</value>
    </subject>
    <collection role="ddc" number="620">Ingenieurwissenschaften und zugeordnete Tätigkeiten</collection>
    <collection role="literaturgattung" number="">Verlagsliteratur</collection>
    <collection role="fulltextaccess" number="">Datei im Netzwerk der BAM verfügbar ("Closed Access")</collection>
  </doc>
  <doc>
    <id>49338</id>
    <completedYear/>
    <publishedYear>2019</publishedYear>
    <thesisYearAccepted/>
    <language>eng</language>
    <pageFirst/>
    <pageLast/>
    <pageNumber/>
    <edition/>
    <issue/>
    <volume/>
    <type>lecture</type>
    <publisherName/>
    <publisherPlace/>
    <creatingCorporation/>
    <contributingCorporation/>
    <belongsToBibliography>0</belongsToBibliography>
    <completedDate>--</completedDate>
    <publishedDate>--</publishedDate>
    <thesisDateAccepted>--</thesisDateAccepted>
    <title language="eng">A decoupling numerical approach for the study of hot cracking formation during high power keyhole mode welding of steel plates with a high sheet thickness</title>
    <abstract language="eng">The weld pool dynamics and shape play a fundamental role in keyhole mode welding. The presented work aims the experimental and numerical investigation of the influence of the weld pool characteristics on the formation of hot cracking. The experimental procedure allows recording the molten pool in the longitudinal section of a butt joint configuration of 15 mm thick structural steel and transparent quartz glass by using a high-speed video camera and two thermal imaging cameras. The observations show that the dimensions of the weld pool vary depending on the depth. The regions close to the surface form a teardrop-shaped weld pool. A bulge-region and its temporal evolution are observed approximately in the middle of the depth of the weld pool, where hot cracking appears. A numerical framework including models for the weld pool dynamics, global temperature field, transient stress state, crystal growth, diffusion and macro-segregation and subroutines for their one-way couplings is developed. The numerically obtained and experimentally observed results are in a good agreement. It is shown that the bulge-region leads to a delay in the solidification behavior, increased temporal tensile stresses and accumulation of impurities in the defect region and hence enhance the probability of hot cracking formation.</abstract>
    <enrichment key="eventName">Colloquium, National Institute of Standards and Technology, Physical  Measurements Laboratory, Applied Physics Division</enrichment>
    <enrichment key="eventPlace">Boulder, Colorado, USA</enrichment>
    <enrichment key="eventStart">15.10.2019</enrichment>
    <enrichment key="InvitedTalks">0</enrichment>
    <author>Antoni Artinov</author>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Keyhole mode welding</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Weld pool shape</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Bulge</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Hot cracking</value>
    </subject>
    <collection role="fulltextaccess" number="">Datei im Netzwerk der BAM verfügbar ("Closed Access")</collection>
    <collection role="literaturgattung" number="">Präsentation</collection>
  </doc>
  <doc>
    <id>49339</id>
    <completedYear/>
    <publishedYear>2019</publishedYear>
    <thesisYearAccepted/>
    <language>eng</language>
    <pageFirst/>
    <pageLast/>
    <pageNumber/>
    <edition/>
    <issue/>
    <volume/>
    <type>lecture</type>
    <publisherName/>
    <publisherPlace/>
    <creatingCorporation/>
    <contributingCorporation/>
    <belongsToBibliography>0</belongsToBibliography>
    <completedDate>--</completedDate>
    <publishedDate>--</publishedDate>
    <thesisDateAccepted>--</thesisDateAccepted>
    <title language="eng">A decoupling numerical approach for the study of hot cracking formation during high power keyhole mode welding of steel plates with a high sheet thickness</title>
    <abstract language="eng">The weld pool dynamics and shape play a fundamental role in keyhole mode welding. The presented work aims the experimental and numerical investigation of the influence of the weld pool characteristics on the formation of hot cracking. The experimental procedure allows recording the molten pool in the longitudinal section of a butt joint configuration of 15 mm thick structural steel and transparent quartz glass by using a high-speed video camera and two thermal imaging cameras. The observations show that the dimensions of the weld pool vary depending on the depth. The regions close to the surface form a teardrop-shaped weld pool. A bulge-region and its temporal evolution are observed approximately in the middle of the depth of the weld pool, where hot cracking appears. A numerical framework including models for the weld pool dynamics, global temperature field, transient stress state, crystal growth, diffusion and macro-segregation and subroutines for their one-way couplings is developed. The numerically obtained and experimentally observed results are in a good agreement. It is shown that the bulge-region leads to a delay in the solidification behavior, increased temporal tensile stresses and accumulation of impurities in the defect region and hence enhance the probability of hot cracking formation.</abstract>
    <enrichment key="eventName">Colloquium, Dept. Materials Science &amp; Engineering, The Ohio State University</enrichment>
    <enrichment key="eventPlace">Columbus, Ohio, USA</enrichment>
    <enrichment key="eventStart">18.10.2019</enrichment>
    <enrichment key="InvitedTalks">0</enrichment>
    <author>Antoni Artinov</author>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Keyhole mode welding</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Weld pool shape</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Bulge</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Hot cracking</value>
    </subject>
    <collection role="ddc" number="620">Ingenieurwissenschaften und zugeordnete Tätigkeiten</collection>
    <collection role="fulltextaccess" number="">Datei im Netzwerk der BAM verfügbar ("Closed Access")</collection>
    <collection role="literaturgattung" number="">Präsentation</collection>
  </doc>
  <doc>
    <id>49341</id>
    <completedYear/>
    <publishedYear>2019</publishedYear>
    <thesisYearAccepted/>
    <language>eng</language>
    <pageFirst/>
    <pageLast/>
    <pageNumber/>
    <edition/>
    <issue/>
    <volume/>
    <type>lecture</type>
    <publisherName/>
    <publisherPlace/>
    <creatingCorporation/>
    <contributingCorporation/>
    <belongsToBibliography>0</belongsToBibliography>
    <completedDate>--</completedDate>
    <publishedDate>--</publishedDate>
    <thesisDateAccepted>--</thesisDateAccepted>
    <title language="eng">Mathematical modeling of the geometrical differences between the weld end crater and the steady-state weld pool</title>
    <abstract language="eng">The geometrical characteristics of the weld end crater are commonly used for the validation of numerical results in welding simulation. A semi-analytical model calculating the cooling stage of the welding process after the moving energy source is turned off has been developed. A solution for various combinations of heat sources and workpieces has been found. The theoretical limits for the heat transfer of the absorbed energy during cooling in a thin plate and a semi-infinite body were studied. It is shown that after turning off the energy source, an additional melting of the base material in longitudinal direction may occur. The developed technique is applied to complete-penetration keyhole laser beam welding of a 2 mm thick austenitic chromium-nickel 316L steel plate at a welding speed of 20 mm/s and a laser power of 2.3 kW. The results show a theoretical increase of the weld end crater length in comparison to the length of the steady-state weld pool of up to 19 %. A shift of the centre of the end crater, in which the solidification of the liquid metal ends, towards the tail of the end crater relative to the axis of the heat source at the time of its termination, was computed. The speed and the direction of crystallization of the molten material in the weld pool and the end crater were found to be different. A good agreement between the computational results and the welding experiments was achieved.</abstract>
    <enrichment key="eventName">ICALEO 2019 - The International Congress on Applications of Lasers &amp; Electro-Optics</enrichment>
    <enrichment key="eventPlace">Orlando, FL, USA</enrichment>
    <enrichment key="eventStart">07.10.2019</enrichment>
    <enrichment key="eventEnd">10.10.2019</enrichment>
    <enrichment key="opus.doi.autoCreate">false</enrichment>
    <enrichment key="opus.urn.autoCreate">true</enrichment>
    <enrichment key="InvitedTalks">0</enrichment>
    <author>Antoni Artinov</author>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Keyhole mode welding</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Weld pool shape</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>End-crater</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Heat conduction</value>
    </subject>
    <collection role="ddc" number="620">Ingenieurwissenschaften und zugeordnete Tätigkeiten</collection>
    <collection role="fulltextaccess" number="">Datei im Netzwerk der BAM verfügbar ("Closed Access")</collection>
    <collection role="literaturgattung" number="">Präsentation</collection>
  </doc>
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