TWI Industrial Member Report Summary 151/1981
By R J Pargeter
A total of twenty-two submerged-arc welds have been examined in the particle analysing scanning electron microscope (PASEM) at the Swedish Institute for Metals Research. All these welds had been examined in previous programmes of work, and the available chemical and microstructural data have been considered with the PASEM data.
A range of flux types was covered, and it was found that in welds made with manganese silicate and calcium silicate fluxes, inclusions with just manganese and silicon, with and without sulphur, predominated. Although manganese was found in the majority of inclusions in welds made with alumina rutile, alumina basic, and basic flux types, aluminium and titanium were also found in many inclusions, apparently principally dependent on the Al2O3, and TiO2, contents of the fluxes. It has been postulated that there may be some duplex inclusions.
An apparent association has been observed between some microstructural constituents and some inclusion types. Coarse grain boundary ferrite and ferrite with aligned martensite, austenite or carbide appeared to be associated with inclusions where just manganese and silicon, with or without sulphur, had been identified, and acicular ferrite appeared to be associated with Al-bearing inclusions.