Investigation of the effect of the slag system of coated electrodes on the efficiency of metal inoculation of a welding bath of low-carbon steel

Abstract

Welded joints are subject to increased requirements for structural condition, as well as a complex of mechanical and special properties. A promising way to regulate the structure of the deposited metal directly in the welding process is its inoculation with ultrafine refractory components. This article presents the results of a study of the structure and mechanical properties of metal deposited with electrodes with basic and rutile coatings containing 5% ultrafine titanium monocarbide powder. It is shown that the addition of ultrafine TIC powder to the electrode coating of the basic type leads to a decrease in the average cross-sectional area of crystallites in the deposited metal by 5 times, from 73000 - 74000 μm2 to 14,000 - 15,000 μm2 and an increase in the shape factor by 1,5 times, from 0,27 to 0,46. The addition of TiC to the rutile-type electrode coating leads to a decrease in the average cross-sectional area of crystallites in the deposited metal by 12-13 times, from 163000 - 164000 μm2 to 11000 to 12000 μm2 and an increase in the shape factor by 2 times, from 0,28 to 0,57. It is established that the effect of inoculation is manifested when using both basic-type coatings and rutile-type coatings. This is due to the fact that the viscosity of liquid welding slags in the crystallization temperature range of a steel welding bath is at the same level of 0,15 – 0,2 Pa·s, and remains so in the flesh up to temperatures of 1325 - 1350 °С, both for basic and rutile slag systems, and equally affects the process of assimilation of ultrafine refractory particles by the metal of the welding bath. It is shown that, despite the inoculation of the metal of the welding bath with refractory particles and the realization of the effect of volumetric crystallization, the final shape of the crystallites depends on the temperature gradient when the heat of the bath is removed into the base metal.The work was carried out within the framework of state support for young Russian scientists — grant of the President of the Russian Federation (No. MK-3849.2021.4).