The welding of austenitic and non-austenitic steels is recommended to carry out at the conditions giving minimal fusion of the base material and using austenitic electrodes. However the structural inhomogenity is observed in the fusion zone due to incomplete stirring in a weld pool and also due to the removal of carbon from the carbon steel to the austenitic weld. We researched fractograms of a fracture of welds, produced by welding low-carbon steel with austenitic-pearlitic and also austenitic electrodes. It was determined that the weld fraction has a complex ductile-brittle character in both cases. It shows that not only the right selection of welded materials influences on the quality of welded joints, but the choice of optimal technology of the welding is important, as well.