Estudio del efecto del diámetro de poros en la resistencia de juntas soldadas con proceso SMAW en tubería de acero ASTM A-36 mediante simulación por elementos finitos

Abstract

The current project arose from the need to determine the effect of the size of an individual pore on the resistance of joints welded with the SMAW process in ASTM A-36 steel pipes under tensile loads. The methodology was based on finding the tensile force maximum so that the chord with the individual porosity does not exceed the elastic limit. Due to the complexity of solving the problem analytically, simulations were carried out in the ANSYS software with geometric modeling in the SOLIDWORKS program. The dimensions used were taken from pipe distribution catalogs for oil pipeline transportation, considering the outer diameter and thickness. Another variable that was taken into account was the diameter of the pore which adopted values of 2, 2.5, 3, 3.5, 4, and 6 mm, respectively. The analysis was carried out in the center of the thickness of the welding bead; the elastic limit of the structural steel under study is 250 MPa. A value that was used to calculate the stress concentration in the pore. The data obtained were analyzed using statistical software with linear regression techniques; therefore, a mathematical expression was found based on three variables: the outside diameter of the pipe and thickness, and finally, the size of the pore (diameter). All of them directly influenced the maximum permitted force to be applied to the welded joint, a value related to its resistance. The analysis showed that the most significant reduction in resistance occurred in pipes with pore diameters greater than 4 mm, with a greater risk of material failure. As a recommendation, the behavior of the mechanical resistance of the joint should be evaluated in other types of discontinuities to observe variations in the maximum force available with different kinds of shapes.