In Situ Modification of CaF2-SiO2-Al2O3-MgO Flux Applied in the Aluminium-Assisted Transfer of Titanium in the Submerged Arc Welding of Carbon Steel: Process Mineralogy and Thermochemical Analysis

Flux formulations are specified to target chemical and physico-chemical parameters. Chemical parameters set flux element transfer behaviours weld metal oxygen contents. Physico-chemical such as slag viscosity, surface tension melting range targeted ensure an acceptable bead profile appearance. Slag detachability is important property required high welding productivity, smooth no entrapment. Here, bead-on-plate tests were made with without powder additions, including aluminium a de-oxidiser. Difficult was observed in runs additions. Mineralogy of the post-weld slags, thermochemical calculations, show that modified due aluminothermic reduction MnO SiO2 from form alumina. Increased quantities spinel phase identified samples, at pool–slag interface. The combined effect increased slag, lowered pool solidus temperature, resulted formation rough morphology, which, turn, caused mechanical fixation bead. modification higher CaF2 content should can be tolerated slag.