Investigation of the residual stresses in HAZ of welded joints in the rigid beam to column connection by finite element method

In the welded joints, residual stresses appear in the areas around the melting pool and the areas that are affected themselves by the welding heat after the completion of heating and cooling welding cycle. The residual stresses reduce the integrity of the metal’s mechanical properties and also the serviceability of the made parts. Recognition and investigation of these stresses is a complicated and pricey process in operation. One can use numerical methods such as finite element for recognizing and investigating the tensions and unwanted welding deformations in order to solve the problem. In this research, regarding the importance of these stresses in construction fittings, a thorough numeric research on the stresses in welding joints has been conducted using Abaqus software. To this purpose, GOLDAK double ellipsoid model has been considered for heating source primitively to ensure the reliability of this evaluating method. Using this technique, the outcome of this model has been compared with the existing technical literature. The heat flux has been encoded in Fortran programming environment with the help of DFLUX subroutine and applied to the original model. Once the temperature history of all thermal analysis groups obtained, mechanical loading analysis will start to identify the residual stress in the fragment. The results demonstrated large amounts of residual stress at the joint site. The amounts of these stresses in some parts of the joint were as much as the yield stress of metal; i.e. to say the metal was formed as plastic at the end of the welding process.