Shielded Metal Arc Welding Consumables for Advanced High Strength Steels.

摘要

To achieve the goal of developing adequate shielded metal arc (SMA) welding consumables for advanced high strength steels, the complex relationship between flux coating and base metal must be understood. This report is concerned with the effect of flux ingredients on high strength steel welding. Submerged arc (SA) welding was first used to investigate the performance of 45 experimental flux compositions chosen from the CaCO3-SiO2-K2SiO3-CaF2-Fe system. Bead-onplate welds were produced on 3/4 in. (19.1 mm) thick HSLA-100 steel plates using a 1/16 in. (1.59 mm) diameter Airco AX-140 welding wire. A 1.5 kj/mm (38.1 kJ/in.) linear heat input was maintained for all welds. To evaluate the effect of the experimental fluxes, two empirical basicity indexes were used: the basicity index (BI) and the Zeke basicity index (Bz). Experimental results showed definite influences of the flux ingredients, both on weld bead morphology and chemical composition of the weld metal. As the basicity of the flux increases, the weld metal oxygen content decreases and the weld metal carbon equivalent (Pcm.) increases. As weld metal oxygen content decreases, the amount of acicular ferrite and Charpy-V-notch impact toughness of the weld metal are observed to increase. The submerged arc welding results also showed that while BI can describe satisfactorily the behavior of basic fluxes, Bz is more appropriate for the acidic fluxes. Using the submerged arc welding data, four fluxes were selected for the extrusion of experimental SMA electrodes. Welding was performed at similar conditions as the submerged arc welds. Slag coverage, weld bead morphology, and weld metal microstructures confirmed the results obtained in submerged arc welding.