TITLE:
Influence of MIG/MAG Welding Process on Mechanical and Pitting Corrosion Behaviors on the Super-Duplex Stainless Steel SAF 2507 Welded Joints
AUTHORS:
Bruno Leonardy S. Lopes, Samuel F. Rodrigues, Eden S. Silva, Gedeon S. Reis, Waldemir dos P. Martins, Juvenilson Costa Damascena, Valdemar S. Leal
KEYWORDS:
Super-Duplex Steels, Welding, Toughness, Pitting Corrosion, Microhardness
JOURNAL NAME:
Materials Sciences and Applications,
Vol.9 No.2,
February
5,
2018
ABSTRACT: The main objective of this
research is to better understand the correlation between the constituent phases
presented in the super-duplex steel SAF 2507 when it is under welding process
by arc shielding gas MIG-MAG (Metal Inert Gas-Metal Active Gas). Conventional short circuit
transfer and derivative STT (Surface Tension Transfer) using the 2594 welding wire
as a filler metal and the effects on welding power in hardness, toughness and
pitting corrosion are considered here. The results showed that the welding
energy (Ew) changed the α/γ-phase’s balance and occasionally
formed σ-phase in ferrite grain
boundaries which led to changes in hardness, toughness and pitting corrosion
resistance in molten zone (MZ), heat activated zone (HAZ) and metal base regions (MB).
Furthermore, the increased amount of γ-phase
improved the pitting corrosion resistance index (PRENγ) mainly in the MZ. This is due to decrease of α-phase fraction and formation of
coarser grains, for higher welding energy. The toughness in the MZ decreased
with less formation of γ-phase,
coalescence of ferritic grains and localized formation of σ-phase, raising the hardness in the HAZ when the welding energy
was lower.