TWI Industrial Member Report Summary 221/1983
By N Bailey
Ways of adding small amounts of titanium to ferritic steel submerged-arc weld metal from the flux have been explored with the aim of ensuring acicular ferrite nucleation when using high oxygen fluxes. This approach could enable high dilution welds to be made on plate of high aluminium content without impairing weld toughncss. Additions of 4% ferro-titanium to a high oxygen, manganese silicate flux markedly improved the toughness of high dilution two-pass and, to a lesser degree, of low dilution multipass weld metal containing 0.1% oxygen. In both cases, a small addition of <0.01%Ti in the weld metal led to a change in microstructure from ferrite with aligned martensite, austenite and carbides to acicular ferrite. Bead-on-plate deposits made with the same flux to which 4 and 8% rutile had been added contained only ~0.004%Ti; the smaller addition gave a mixed microstructure but the larger addition led to an acicular ferrite microstructure.