Microstructures and properties of uhss laser welds

Abstract

Conventional welding processes often do not provide sufficient joins in high strength steels with multiphase microstructures. One of promising way is laser beam welding – working without filler metal, with sufficient capacity for automotive and transportation industry (where the amount of UHS steels increases each year as well as length of laser welds).Contribution compares microstructures and properties of HSS joins after WIG, MIG and laser welding. Effects of the main welding parameters (heat input, welding speed etc.) are studied on multiphase TRIP900 steel tubes and martensitic sheets DOCOL1200, perspective materials for seat frames and other components. While strength of conventional welds decrease significantly, after laser welding remain nearly unaffected. Because fracture nature changes during loading, depending on welding method, failure mechanisms after cross tension tests have also been studied.Conventional welding processes often do not provide sufficient joins in high strength steels with multiphase microstructures. One of promising way is laser beam welding – working without filler metal, with sufficient capacity for automotive and transportation industry (where the amount of UHS steels increases each year as well as length of laser welds).Contribution compares microstructures and properties of HSS joins after WIG, MIG and laser welding. Effects of the main welding parameters (heat input, welding speed etc.) are studied on multiphase TRIP900 steel tubes and martensitic sheets DOCOL1200, perspective materials for seat frames and other components. While strength of conventional welds decrease significantly, after laser welding remain nearly unaffected. Because fracture nature changes during loading, depending on welding method, failure mechanisms after cross tension tests have also been studied.