The influence of thermal properties and preheating on residual stresses in welding

A 2D finite element model has been carried out to analyse temperature distribution in butt weld joints. Temperature fields have been investigated by varying both thermal properties and an initial preheating treatment. Successive thermo-mechanical analyses were performed to evaluate resulting residual stresses. Temperature distribution and residual stresses were determined in a single-pass butt joint welded by Gas Metal Arc Welding (GMAW) process. A finite element parametric model was carried out and the technique of ‘element birth and death’ was adopted to simulate the process of filler metal addition. By means of finite element analysis high stresses were evaluated, with particular regard to Fusion Zone (FZ) and Heat-Affected Zone (HAZ). The influence of thermal properties and preheating on residual stresses in welding was also investigated. In the last few years, various experimental destructive and non-destructive methods were developed to evaluate residual stresses. However it is impossible to obtain a full residual stress distribution in welded structures by means of experimental methods. This disadvantage can be solved by means of computational analysis, which allows to determine the whole stress and strain fields in complex structures. This paper demonstrates that the technique of ‘element birth and death’ is suitable to simulate welding processes. Moreover, the study of welded joints should take into consideration the effect of material thermal properties and preheating treatment.