Analysis of dynamic plasma behaviors in gas metal arc welding by imaging spectroscopy

Masaya Shigeta, Shota Nakanishi, Manabu Tanaka, Anthony B. Murphy

Research output: Contribution to journalArticlepeer-review

15 Citations (Scopus)


For gas metal arc welding, the effect of CO2 mixture in a shielding gas on a metal transfer process was investigated through the observation of the plasma characteristics and dynamic behavior at the droplet's growth-separation-transfer by the temperature measurement methods which were suitable respectively to the argon plasma region and the metal plasma region. At the present experimental conditions, the metal transfer process was a spray transfer type with 100%Ar shielding gas. On the other hand, with 85%Ar+15%CO2 shielding gas, the metal transfer process was a globular transfer type in which the arc length was shorter, the width was narrower, and the time interval of the droplet separation was longer. For both shielding gases, the metal plasma region near the arc central axis exhibited 6500-7500 K which was lower than the argon plasma region. With 85%Ar+15%CO2 shielding gas, when the metal droplet grew below the electrode wire, the region below the droplet has a high plasma temperature and a high concentration of iron vapor which surrounded the droplet. The region also exhibited a remarkably high electron number density. At the spray transfer process, the argon plasma region had the electron number density twice higher than the metal plasma region. Meanwhile, at the globular transfer process, the metal plasma region had a higher electron number density than the argon plasma region, which corresponded to a higher electrical conductivity near the arc axis. This means that the electric current goes through the arc axis easier than the spray transfer process. This condition increases the temperature below the droplet. The thermal expansion increases the force preventing the droplet from falling down. In consequence, the metal transfer takes the globular transfer type.

Original languageEnglish
Pages (from-to)118-125
Number of pages8
JournalYosetsu Gakkai Ronbunshu/Quarterly Journal of the Japan Welding Society
Issue number2
Publication statusPublished - 2015
Externally publishedYes


  • Arc plasma dynamics
  • Gas metal arc welding
  • Imaging spectroscopy
  • Metal transfer
  • Metal vapor

ASJC Scopus subject areas

  • Mechanics of Materials
  • Mechanical Engineering
  • Surfaces, Coatings and Films
  • Metals and Alloys


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