Prediction of acicular ferrite from flux ingredients in submerged arc weld metal of C-Mn steel

Abstract

The prediction model has been developed for low carbon steel weld metal acicular ferrite microstructure as a function of flux ingredients such as CaO, MgO, CaF2 and Al2O3 in submerged arc welding carried out at fixed welding parameters. The results of quantitative measurements of acicular ferrite (AF) on eighteen no. of weld metal samples were utilised for developing the prediction model. Among the flux ingredients, CaO appears to be most important as an individual as well as interaction with other ingredients in controlling the amount of acicular ferrite content in the weld metal. Furthermore, formation of acicular ferrite is also related to the weld bead geometry which is influenced by flux ingredients. The prediction equation for acicular ferrite has been checked for adequacy by performing separate experiments on welding using randomly designed flux. The isoresponse curves were developed to show the level of acicular ferrite content at different percentage of flux ingredients. © 2005 ISIJ.