Welding in the World

, Volume 63, Issue 1, pp 3–10 | Cite as

Welding design methodology for optimization of phase balance in duplex stainless steels during autogenous arc welding under Ar–N2 atmosphere

  • A. Rokanopoulou
  • P. SkarvelisEmail author
  • G. D. Papadimitriou
Research Paper


This study deals with the selection of appropriate welding parameters during autogenous arc welding of duplex stainless steels in order to achieve an optimum phase balance of austenite and ferrite in the as-welded microstructure. Specimens of duplex stainless steel 2205 with dimensions (40 × 40 × 10) mm3 were welded using autogenous arc welding under 95% Ar + 5% vol. N2 atmosphere. The weld pool temperature was measured by non-contact infrared temperature measurement, the weld bead dimensions were determined using scanning electron micrographs, and the final nitrogen concentration was evaluated by optical emission spectroscopy. The kinetics of nitrogen absorption and desorption in molten duplex stainless steel was discussed and all the relevant variables were presented. The effect of welding current and speed on the final nitrogen concentration was also discussed. Finally, based on this analysis, a method was set up which can be used to optimize the phase balance by using predictive methods of the Ferrite Number, such as the Welding Research Council (WRC)-92 diagram.


Duplex stainless steel Arc welding Nitrogen solubility Kinetic model Phase balance 


\( \frac{d{m}_N}{dt} \)

rate of mass transfer of nitrogen (kg s−1)


rate constant for the reaction of absorption of monatomic nitrogen in a stainless steel melt (kg m−2 s−1 atm−1)


weld pool surface area (m2)


the monatomic nitrogen content of the arc (atm)


the monatomic nitrogen content of the arc plasma required for equilibrium with the nitrogen in the steel (atm)


the density of the molten weld metal (kg m−3)


the weld pool volume (m3)


weld pool radius (m)


weld pool depth (m)

fN, T

the activity coefficient of nitrogen in the stainless steel melt at temperature T


first-order interaction parameter of nitrogen


second-order interaction parameter of nitrogen


the initial nitrogen concentration of the stainless steel


wt% equivalent concentration of element i (the content of the reference element which provides the same nitrogen activity as the content of element i)


equivalent factor


wt% concentration of alloying element i in stainless steel


difference between the weld pool temperature and the melting point of the stainless steel


welding speed (m/s)


weld pool diameter (m)


rate constant for the reaction of nitrogen desorption from the weld pool to the arc atmosphere (kg m−2 s−1 (wt%)−2)


the final nitrogen concentration in the solidified steel (wt%)


nitrogen concentration in the weld pool for equilibrium with the nitrogen in the gas (wt%)


the activity coefficient of oxygen in the stainless steel melt


the activity coefficient of sulfur in the stainless steel melt


wt% concentration of oxygen in the weld pool


wt% concentration of sulfur in the weld pool


dissociation temperature of diatomic to monatomic nitrogen


weld pool temperature



The State Scholarships Foundation of Hellas (IKY) is gratefully acknowledged for the financial support to A. Rokanopoulou (Grant No. 4327) and P. Skarvelis (Grant No. 4246).


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© International Institute of Welding 2018

Authors and Affiliations

  1. 1.School of Mining and Metallurgical Engineering, Laboratory of Physical MetallurgyNational Technical University of AthensZografouGreece

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