Indentation hardness

Arc (geometry)

Carbon steel

Engineering

Metallurgy

Materials science

Niobium

Ductility (Earth science)

Creep

Grain boundary

Arc welding

Mechanical engineering

Microstructure

Composite material

Corrosion

Welding

Flux (metallurgy)

Submerged arc welding

Journal of Materials Processing Technology

The present work evaluates the effect of adding 3 wt.% of NbC and Nb2O5 to a commercial SAW flux on the microstructure and mechanical properties of the weld metal of ASTM 131 AH31 plates. The analyses of the weld bead microstructure indicated the presence of three weld zones, as expected, enhancing the presence of fine and coarse HAZ. Microscopy and EDS indicated that Nb dissociates from the original compound and precipitates along the grain boundaries of the iron matrix as niobium oxide. Mechanical characterization evidenced that NbC and Nb2O5 added to a commercial SAW flux increased the microhardness values by ∼40% and ∼140%, respectively. The addition of NbC decreased the ductility of the weld metal, whereas the addition of Nb2O5 increased it. The results obtained indicate a potential product for high wear resistance applications.

Effect of niobium addition on the flux of submerged arc welding of low carbon steels