Defocusing Techniques for Multi-pass Laser Welding of Austenitic Stainless Steel

Miikka Karhu, Veli Kujanpää

Research output: Contribution to journalArticleScientificpeer-review

6 Citations (Scopus)

Abstract

This study introduces an experimental work carried out in multi-pass laser welding with cold filler wire and laser-arc hybrid welding of thick section austenitic stainless steel. As it has been demonstrated earlier, hybrid and cold wire welding with a keyhole-mode can offer very efficient way to produce multi-pass welds in narrow gap thick section joints. However, when multi-pass welding is applied to one pass per layer method without e.g. scanning or defocusing, the used groove width needs to be very narrow in order to ensure the proper melting of groove side walls and thus to avoid lack of fusion/cold-run defects. As a consequence of the narrow groove, particularly in thick section joints, the accessibility of an arc torch or a wire nozzle into the very bottom of a groove in root pass welding can be considerably restricted. In an alternative approach described in this paper, a power density of a laser beam spot was purposely dispersed by using a defocusing technique. In groove filling experiments, a power density of defocused laser beam was kept in the range, which led the welding process towards to conduction limited regime and thus enabled to achieve broader weld cross-sections. The object was to study the feasibility of defocusing as a way to fill and bridge wider groove geometries than what can be welded with focused keyhole-mode welding with filler addition. The paper covers the results of multi-pass welding of up to 60 mm thick joints with single side preparations.
Original languageEnglish
Pages (from-to)53-64
JournalPhysics Procedia
Volume78
DOIs
Publication statusPublished - 2015
MoE publication typeA1 Journal article-refereed

Fingerprint

laser welding
austenitic stainless steels
defocusing
welding
grooves
wire
fillers
radiant flux density
arcs
laser beams
torches
nozzles
fusion
melting
conduction
preparation
scanning
cross sections
defects
geometry

Keywords

  • laser welding
  • defocusing
  • multi-pass
  • austenitic manganese steel

Cite this

Karhu, Miikka ; Kujanpää, Veli. / Defocusing Techniques for Multi-pass Laser Welding of Austenitic Stainless Steel. In: Physics Procedia. 2015 ; Vol. 78. pp. 53-64.
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abstract = "This study introduces an experimental work carried out in multi-pass laser welding with cold filler wire and laser-arc hybrid welding of thick section austenitic stainless steel. As it has been demonstrated earlier, hybrid and cold wire welding with a keyhole-mode can offer very efficient way to produce multi-pass welds in narrow gap thick section joints. However, when multi-pass welding is applied to one pass per layer method without e.g. scanning or defocusing, the used groove width needs to be very narrow in order to ensure the proper melting of groove side walls and thus to avoid lack of fusion/cold-run defects. As a consequence of the narrow groove, particularly in thick section joints, the accessibility of an arc torch or a wire nozzle into the very bottom of a groove in root pass welding can be considerably restricted. In an alternative approach described in this paper, a power density of a laser beam spot was purposely dispersed by using a defocusing technique. In groove filling experiments, a power density of defocused laser beam was kept in the range, which led the welding process towards to conduction limited regime and thus enabled to achieve broader weld cross-sections. The object was to study the feasibility of defocusing as a way to fill and bridge wider groove geometries than what can be welded with focused keyhole-mode welding with filler addition. The paper covers the results of multi-pass welding of up to 60 mm thick joints with single side preparations.",
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Defocusing Techniques for Multi-pass Laser Welding of Austenitic Stainless Steel. / Karhu, Miikka; Kujanpää, Veli.

In: Physics Procedia, Vol. 78, 2015, p. 53-64.

Research output: Contribution to journalArticleScientificpeer-review

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