Influence of the volume of deposited weld metal on the service life of the vertical steel tank in the North

Abstract

The structural and mechanical inhomogeneity of welded joints, design and technology defects, residual welding stresses and deformations introduced during the technological processes of constructing and repairing are common in welding vertical steel tanks. Hence, the problem of increasing the operational strength of welded joints is a crucial task. The present article describes the key stages of the structure formation of the metal of the heat-affected zone during the welding of low-alloyed steels used for tank manufacturing in the range of permissible cooling rates in the temperature range from 600 to 500°C. Based on the analysis of continuous cooling transformation diagrams and using the expression for finding the volume of deposited metal during welding in the range of permissible cooling rates, the weld deposit area was calculated. The hardness values are obtained using continuous cooling transformation diagrams for specific grades of steel. It has been established that the strength characteristics change depending on the volume of the deposited weld metal. We have provided graphs that allow determining the mechanical properties of the heat-affected zone metal by area of the weld deposit. The form of a weld is determined from the area found at the optimum rate of cooling temperature, which ensures acceptable cold resistance and strength of the heat-affected zone metal. Subsequently, the volume of deposited weld metal could significant influence the service life of the tanks, taking into account the stress concentrators.