The effect of shielding-gas compositions on the microstructure and mechanical properties of stainless steel weldments

This study aims to examine how the microstructure and mechanical properties of AISI 304 stainless steel welds are influenced by the shielding gas. The spatter rates increase as the CO2 content of the Ar + CO2 shielding-gas mixtures increases from 2 to 20%. The notch toughness of all the weld metals is affected by the delta-ferrite and oxygen potential. At room temperature, the notch toughness property is strongly dependent on oxygen potential. At - 196 degrees C, both delta-ferrite and oxide inclusions are detrimental to the notch toughness properties, but the delta-ferrite plays a much more important role at this temperature. Both vermicular and lathy ferrite are observed, and the ferrite content decreases as the CO2 level of the Ar + CO2 mixtures increases from 2 to 20%. (C) 1998 Elsevier Science S.A. All rights reserved.