The aim of this paper is to demonstrate the influence of the single butt joint design of TIG welding on the thermal stresses for carbon steel type St-37. The butt welding was performed by V angles 30°,45°,60° and 90° and the thermal stresses analysis is based on the local moving heat flux. The numerical model developed by ANSYS12
software based on solving the three dimensional energy equation, considering moving heat source and temperature dependent material properties. Temperature and stresses distributions were obtained function of time. From the results, it is evident that the
joint design has an important role in the welding process, when the edge angle of the welding region gets bigger, the faults get less due to increase of heat flux in the welding region. It can be concluded that the specimen with less than 6mm thickness can be welded without edge angle preparation, due to increase the thermal stresses
when edge angle is evident and higher thermal stresses distribution was at edge angle 60° and lowest thermal stresses distribution was at 90°.