Scientific paper ID 2009 : 2020/3

Weld strength is a complex characteristic that depends on a large number of factors, such as the size and shape of the weld, the properties of the materials of the welding elements and of the additive in material, the welding technology and the associated zones of thermal influence in the seam, imperfections in stitching etc. Numerous studies on the weld structure between iron-based materials have shown that there is considerable heterogeneity due to the difference in the crystal lattice of the elastic medium.

The purpose of the present study is to evaluate the possible influence of weld stiffness and elastic medium in the area of thermal zone on the concentration coefficient of weldings.

The objective is achieved by virtual experiments to determine the stress state in different parts in a butt weld. A 3D model of welded specimens has been made in CAD, for which literature data are available on the hardness of the elastic medium in different weldings and thermal impact zones. The model was created without taking into account the typical geometric deviations due to the welding technology. The areas with a relatively homogeneous structure are pre-created as separate elements and the model is assembled in CAD. The structure is loaded statically by the finite element method at the yield limit. The stresses in the weld and in the areas around it are calculated. The typical effect of structural changes in the weld on the stress state in the weld is determined. There is an uneven load, which is explained by the different deformation behavior in the different areas of the welding. The relative changes in the stress in the welding zones are calculated and values within 4 - 25% of the theoretical load are obtained.

The results can justify a common coefficient of concentration in the weld due to structural changes.