The Structure of the Welded Joints between High-Strength Steel USIBOR 22MnB5 and Mild Steel H340LAD+Z140-M-B-O Made by Resistance Spot Welding

The application of different types of materials, e.g. coated high-strength materials and galvanized steels in the manufacturing of car bodies, requires the verification of their weldability. Despite the application of new, unconventional fusion welding technologies (CMT, laser), resistance spot welding holds a dominant position in the production of car bodies of lower and middle class. Resistance welding technology is characterized by a high rate of heating and cooling, thus affecting the final properties of the welded joint. The paper is focused on the structure analysis of the welded joint of high strength steel USIBOR 22MnB5 with Al-Si coating and galvanized mild steel H340LAD+Z140-M-B-O made by resistance spot welding