Role of surface-active elements during keyhole-mode laser welding

B. Ribic, S. Tsukamoto, R. Rai, Tarasankar Debroy

Research output: Contribution to journalArticle

16 Citations (Scopus)

Abstract

During high power density laser welding of mild steel, the keyhole depth, liquid metal flow, weld geometry and weld integrity are affected by base-metal sulfur content and oxygen (O2) present in the atmosphere or shielding gas. The role of these surface-active elements during keyhole-mode laser welding of steels is not well understood. In order to better understand their effects, welding of mild steel specimens containing various concentrations of oxygen and sulfur are examined. In addition, a numerical model is used to evaluate the influence of the surface-active elements on heat transfer and fluid flow in keyhole-mode laser welding. Increase in base-metal sulfur concentration or O2 content of shielding gas results in decreased weld widths. Sulfur results in a negligible increase in penetration depth whereas the presence of O2 in shielding gas significantly affects the weld penetration. It has earlier been proposed that oxygen, if present in the shielding gas, can get introduced into the weld pool resulting in formation of carbon monoxide (CO) at the keyhole surface and additional pressure from CO can result in increased penetration. Numerical modelling has been used in this work to understand the effects of formation of CO on the keyhole and weld geometries.

Original languageEnglish (US)
Article number485203
JournalJournal of Physics D: Applied Physics
Volume44
Issue number48
DOIs
StatePublished - Dec 7 2011

Fingerprint

laser welding
Laser beam welding
Laser modes
shielding
Welds
sulfur
carbon monoxide
Sulfur
Shielding
penetration
steels
Carbon Monoxide
Gases
gases
Carbon monoxide
oxygen
Oxygen
Carbon steel
geometry
liquid metals

All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Acoustics and Ultrasonics
  • Surfaces, Coatings and Films

Cite this

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title = "Role of surface-active elements during keyhole-mode laser welding",
abstract = "During high power density laser welding of mild steel, the keyhole depth, liquid metal flow, weld geometry and weld integrity are affected by base-metal sulfur content and oxygen (O2) present in the atmosphere or shielding gas. The role of these surface-active elements during keyhole-mode laser welding of steels is not well understood. In order to better understand their effects, welding of mild steel specimens containing various concentrations of oxygen and sulfur are examined. In addition, a numerical model is used to evaluate the influence of the surface-active elements on heat transfer and fluid flow in keyhole-mode laser welding. Increase in base-metal sulfur concentration or O2 content of shielding gas results in decreased weld widths. Sulfur results in a negligible increase in penetration depth whereas the presence of O2 in shielding gas significantly affects the weld penetration. It has earlier been proposed that oxygen, if present in the shielding gas, can get introduced into the weld pool resulting in formation of carbon monoxide (CO) at the keyhole surface and additional pressure from CO can result in increased penetration. Numerical modelling has been used in this work to understand the effects of formation of CO on the keyhole and weld geometries.",
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Role of surface-active elements during keyhole-mode laser welding. / Ribic, B.; Tsukamoto, S.; Rai, R.; Debroy, Tarasankar.

In: Journal of Physics D: Applied Physics, Vol. 44, No. 48, 485203, 07.12.2011.

Research output: Contribution to journalArticle

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AU - Rai, R.

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