The impact of stress on changes in magnetization is one of the most complex issues of magnetism. Magnetic techniques are the most important non-destructive testing technologies to characterize the mechanical features of ferromagnetic materials based on the physical principle of magnetic-stress coupling. Magnetic Barkhausen Noise measurement was used in order to estimate stress state in boat welding. The results have shown that magnetic properties of ferromagnetic materials are stress-dependent. A qualitative correlation was found between places with residual stress and areas with increased values of the gradients of the magnetic Barkhausen noise components. Further research is now in progress in order to develop the quantitative relationships.