The process of stamping thick steel sheets, especially after welded joints, is one of the more challenging issues in modern metal forming technology. This paper focuses on the analysis of post-weld forming of 8 mm thick sheet metal, with particular reference to the influence of the weld zone, heat affected zone (SWC) and residual stresses on the course of the forming process and deformation characteristics. Experimental tests were carried out on steel specimens joined by active gas shielded welding (MAG). After the welds were made, the specimens were subjected to stamping tests. The observations showed significant differences in the strain distribution in the weld regions compared to the parent material, which manifested itself as increased stress concentration and a tendency to initiate microcracks especially in the SWC.In addition, numerical simulations using the finite element method (FEA) were carried out to map the actual process flow and identify key areas of cracking risk. The simulation results showed good correlation with empirical observations and confirmed the influence of local material strengthening in the weld region and geometric discontinuities on the reduced deformability of the plate. Variable hardness gradients and tensile stresses acting perpendicular to the weld line proved to be particularly significant. Successful post-weld pressing of thick plates requires not only optimisation of the parameters of the forming process itself (forces, punch radius, process speed), but also appropriate preparation of the weld - by controlling the SWC structure, applying stress-relieving heat treatment or preemptively removing the layer with microcracks in the future pressing area. Particularly for thicknesses above 6-8 mm, local differences in mechanical properties become crucial for maintaining material continuity and avoiding cracks. This article highlights the importance of an integrated approach to the design of post-weld sheet metal stamping technology, in which not only the geometry of the tool, but also the previous stages of blank preparation, the quality of the welded joint and the structural characteristics of the material in the transition zones play an important role.

Acknowledgement: This research was founded by the Ministry of Science and Higher Education in Poland, allocated at Poznan University of Technology, project number: 0613/SBAD/4940.