ARC WELDING OF ADVANCED HIGH STRENGTH STEELS FOR CAR-BODY COMPONENTS

摘要

Car bodies are increasingly made with advanced high-strength steels, both to reduce vehicle weight and to improve passenger safety. In the last years, new high-manganese TWIP steels have been proposed for fabricating these components, due to their excellent combination of strength and toughness. These steels have an austenitic structure which is strengthened mainly by the possibility to deform via mechanical twinning. However, a widespread usage of TWIP steels for car body parts is conditional on the employment of appropriate welding methods, especially if dissimilar welding must be performed with other steel grades. Therefore, continuous butt welding between TWIP steel sheets and frequently employed high strength automotive steel sheet grades is examined here. Metal active gas welding was employed to join the TWIP steel with either a boron-alloyed hot-stamping steel or a dual-phase cold-forming one, and the weldments were characterized by metallography, tensile and microhardness tests, and fractography.