Analysis of thermal affectation and stresses generated by welding in bus structure

Abstract

Introduction: In Ecuador in recent years there have been various traffic accidents in which interprovincial buses are involved due to numerous factors that produced these accidents that cause human losses and material damages. Objective: The objective of this work is to analyze the quality and safety of the occupants when they are transferred from one place to another, through the study of the thermal affectation in the microstructure of the material during the welding process. Methodology: The work methodology consists of analyzing the microstructure of welded ASTM A-500 steel specimens through SMAW and GMAW processes and considering standard welding parameters that are used in the country's bodywork industries. For the analysis, the front part of the bus has been considered due to the importance of the loads on this element, the union of the specimens was developed by means of a butt joint and the analysis of thermal stresses in the material was executed in the Ansys software. Results: The microstructural analysis of the specimens before and after the welding processes show the presence of pearlite and ferrite mostly without changes in the morphology of the material, from the thermal analysis it is determined that the GMAW process presents a higher index of thermal conductivity with a value of 0,9255W/ and the maximum deformation that the material presents is 0.17167 mm. Conclusions: Under the parameters analyzed, since there are no changes in the microstructure, it is concluded that a heat treatment is not necessary before or after the welding processes, therefore the mechanical properties of the material are not affected. From thermal analysis it is determined that the zone of influence of heat is approximately 1.5-2mm.