The origins of acicular ferrite in gas metal arc and submerged arc welds
Brothers, Daniel G.
Fox, Alan G.
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The nature of weld metal inclusions in relation to the formation of acicular ferrite was investigated. Gas-metal arc welds (GMAW) on High Strength Low Alloy (HSLA) plate with varying amounts of oxygen and/or carbon dioxide added to the argon cover gas and submerged arc welds (SAW) on HY-100 plate with five different fluxes were analyzed. This analysis determined the effect of weld metal composition on non-metallic inclusion composition and the ultimate effects on the formation of acicular ferrite. Scanning and transmission electron microscopy with energy dispersive x-ray analysis were used to determine inclusion size distribution, concentration and composition. This investigation revealed that the inclusions were complex MnO-A1203-SiO2-TiO2 oxides which contain a titanium-rich compound, Pyrophanite (MnTi03), existing as a faceted particle in those inclusions promoting acicular ferrite formation. From these results and the research of others such as Grong/Matlock and Ramsay/Matlock/ Olson it is concluded that the formation of acicular ferrite does depend on non- metallic inclusion composition demonstrating the importance of weld wire composition for achieving welds with optimum mechanical properties.
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The role of titanium in the non-metallic inclusions which nucleate acicular ferrite in the submerged arc weld (SAW) fusion zones of Navy HY-100 steel Fox, A.G.; Brothers, D.G. (Pergamon, 1995-04-01);The origin of acicular ferrite in the weld metal of submerged arc weldments on high strength steels is very complex and depends upon the chemical composition for the steel base plate and filler wire, the composition of the ...
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