Flux Composition Dependence of Microstructure and Toughness of Submerged Arc HSLA Weldments

摘要

Twenty eight reagent grade fused fluxes from the CaF2-CaO-Si02 system were used to produce bead-on-plate and double-V-groove submerged arc welds on a quenched-and-tempered niobium HSLA steel. An E70S3 welding wire was used with two different inputs-namely 1.9 and 3.3 k/mm (48.3 and 83/8 k/in.) A niobium microalloyed steel was selected because of its fine grained microstructure, high yield strength, and high toughness at low temperatures. Fluxes from the CaF2-CaO-SiO2 system were selected because of their low oxygen potential, and their ability to produce low oxygen (80-450 ppm) welds. Quantitative metallography and chemical analysis were performed on the welds. The chemical behavior of this flux system has been characterized with respect to manganese, silicon, niobium, and sulfur.