EFFECT OF CARBON-FLUORIDE-CONTAINING FLUX ADDITIVE ON THE LEVEL OF CONTAMINATION OF WELD METAL BY OXIDE NON-METALLIC INCLUSIONS*

Abstract

When using certain grades of flux, the required mechanical properties of the weld metal (in particular, impact toughness at low temperatures) are not always achieved due to the formation of a large number of non-metallic inclusions. Most of these inclusions are oxides (regardless of whether they are exogenous or endogenous). The content of non-metallic inclusions in the weld metal, in turn, depends on the amount of total oxygen. Since the solubility of oxygen in solid metal is low, the total oxygen content characterizes the level of contamination with non-metallic inclusions. When using existing fluxes for welding low-alloy steels, an increased total oxygen content and, consequently, an increased number of non-metallic inclusions are observed. Currently, a reduction in the content of non-metallic inclusions in weld metal during automatic submerged arc welding is achieved by using weakly oxidizing fluxes. However, such fluxes have unsatisfactory welding properties and are rarely used for welding low-alloy steels. When using oxidizing fluxes, the weld metal is saturated with oxygen as a result of silicon and manganese reduction processes.