Characterizing Oxide Inclusions in Welded Lean Duplex Stainless Steels and Their Influence on Impact Toughness

Abstract

In newly developed 2101 lean duplex stainless steel, oxide inclusions have been detected on welded metal zones after subjecting them to flux-cored arc welding with an E2209T1-1 flux-cored filler metal. These oxide inclusions directly affect mechanical properties of the welded metal. Hence, a correlation requiring validation has been proposed between oxide inclusions and mechanical impact toughness. Accordingly, this study employed scanning electron and high-resolution transmission electron microscopy to assess the correlation between oxide inclusions and mechanical impact toughness. Investigations revealed that the spherical oxide inclusions comprised a mixture of oxides in the ferrite matrix phase and were close to intragranular austenite. The oxide inclusions observed were titanium- and silicon-rich oxides with amorphous structures, MnO with a cubic structure, and TiO2 with an orthorhombic/tetragonal structure, derived from the deoxidation of the filler metal/consumable electrodes. We also observed that the type of oxide inclusions had no strong effect on absorbed energy and no crack initiation occurred near them.

Kinetics of Intermetallic Phase Precipitation in Manual Metal Arc Welded Duplex Stainless Steels

“…The results of research on the structure-properties relationship of welded joints produced by the flux cored arc welding (FCAW) process indicate the formation of titaniumand silicon-rich oxides. However, their presence did not cause a significant change in the impact strength of the welded joints [9].…”