Effect of Automatic Arc Welding Conditions on the Geometric Parameters of Low-Carbon Steel Welded Butt Joints Made Using an Experimental Flux

Abstract

The metallurgical industry in the Russian Federation has accumulated a significant amount of slags produced during the manufacture of steels and cast iron. The presence of slag dumps adversely affects the ecology of regions with metallurgical enterprises. During the reduction of iron from slags, an oxide agglomerate becomes a by-product, which can be considered as a flux composition for arc welding/surfacing under a flux layer, fillers for powder wires, and coatings for welding electrodes. The purpose of this work is to study the possibility of arc welding using the flux developed in this work and to determine the optimum welding conditions that ensure the geometric parameters of a weld according to GOST 8713–79 and the required quality of the welded joint (absence of internal defects). The butt-welded joints of 5-mm-thick VSt3sp sheet steel are studied; they were formed by automatic dc welding under a flux layer with forced formation of a root bead on ceramic linings using the flux from the processed metallurgical slag of an electric steelmaking enterprise. Automatic welding of flat samples is carried out on a tractor-type ADF-1250 welding machine using a wire 3 mm in diameter at a constant welding speed of 54 cm/min by varying the current and the arc voltage in the range 400–600 A and 27–37 V, respectively. The research methods are as follows: the estimation of the quality of welded joints by visual measuring and X-ray inspection and the determination of the deformation of samples by laser scanning and computer processing of 3D models. Statistical modeling is performed in the form of a two-factor experiment to obtain adequate regression equations for the effect of welding conditions on the geometric parameters of the weld, namely, the reinforcement height and the weld width on the front and back of a welded joint. The possibility of producing welding fluxes from the metallurgical slags of an electric steelmaking enterprise and their use to create welded joints is shown. The optimum conditions for arc welding of thin-walled sheet parts made of low-carbon steel with forced formation of a root bead on ceramic linings have been determined to ensure the absence of internal defects in the form of pores, cracks, and imperfections; the minimum residual deformations; and compliance of the weld size with the requirements of the existing standard. The nominal geometric parameters of a weld according to GOST 8713-79-S4 correspond to the following welding conditions: the welding speed is 54 cm/min, the welding current 550 A, and the arc voltage is 30 V. The results obtained can be applied in metallurgical electric steelmaking enterprises producing low-carbon steel for the development of technologies using welding materials from slag.