Arc Welding of Dissimilar Metals: FEM and Experiments

ABSTRACT

The temperature history of the welded components has a significant influence on the structural changes, residual stresses, strains. Classical solutions for the transient temperature field such as Rosenthal's solutions dealt the semi-infinite and infinite bodies subjected to an instant point heat source, line heat source or surface heat source. These solutions can be used to predict the temperature field far from the heat source but fail to predict the temperatures near it. Goldak et al. have introduced the 3D double ellipsoidal heat source to predict the temperature field of semi-infinite body. For thin plates, the source influence in the thickness direction could be neglected and the source becomes a Gaussian surface-distributed heat source or an elliptical disk heat source. Assuming an elliptical disk heat source, several theoretical and experimental investigations on heat transfer in copper - low carbon steel arc welded joints are presented in the first part of the paper. An actual theoretical method, using FEM-based analysis, is availed for the temperatures prediction in the welded joints. Using thin sheets, temperature variation in the thickness direction is negligible and heat flow is considered two-dimensional. Convection and radiation influence and thermo-physical properties depending on the temperature are considered in the mathematical model proposed by the authors. Several measurements and visualization of the temperatures distribution have been made during the welding process, using infrared thermography. Conclusions on the FEM analysis and the measurements by the thermography method of the temperatures field are finally presented. In the second part of the paper, the study presents also the influence of the welding process on the structural modifications and grains size in the HAZ of low carbon steel and copper.

KEYWORDS: dissimilar metals, arc welding, FEM, thermal field, structural modifications