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Investigating defects caused by narrow pool shapes in deep penetration welding

  • 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. 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. 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 fromLaser 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. 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. 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. 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.zeige mehrzeige weniger

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Autor*innen:Marcel BachmannORCiD, Xiangmeng MengORCiD, Antoni ArtinovORCiD, Michael RethmeierORCiD
Dokumenttyp:Zeitschriftenartikel
Veröffentlichungsform:Graue Literatur
Sprache:Englisch
Titel des übergeordneten Werkes (Englisch):Laser Systems Europe
Jahr der Erstveröffentlichung:2022
Organisationseinheit der BAM:9 Komponentensicherheit
9 Komponentensicherheit / 9.3 Schweißtechnische Fertigungsverfahren
Verlag:Europa Science
Verlagsort:Cambridge, UK
Ausgabe/Heft:57
Erste Seite:28
Letzte Seite:29
DDC-Klassifikation:Technik, Medizin, angewandte Wissenschaften / Ingenieurwissenschaften / Ingenieurwissenschaften und zugeordnete Tätigkeiten
Freie Schlagwörter:Laser beam welding; Solidification; Weld pool shape
Themenfelder/Aktivitätsfelder der BAM:Material
ISSN:1759-0752
Verfügbarkeit des Dokuments:Datei im Netzwerk der BAM verfügbar ("Closed Access")
Datum der Freischaltung:15.02.2023
Referierte Publikation:Nein
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