Welding Journal Research Supplement

Abstract

High-frequency induction welding (HFIW) is the predominant process used to weld strip edges during the production of automotive structural tubing. The high-throughput nature of HFIW makes it ideal for welding advanced high-strength steel tubes; however, oxides containing Al, Mn, and Si can sometimes form along the strip edges and become entrapped within the weld bond line. In welds containing oxide inclusions, the strength and ductility of the weld joint will be significantly decreased. High operational costs of running a tube make it difficult to determine favorable conditions for oxide inclusion formation through mill trials. This study shows that the Gleeble was capable of providing insights on appropriate welding temperatures to achieve defect-free HFIW in TRIP 690. The simulated samples reproduced the bond line and heat-affected zone microstructures of the industrially produced HFIW welds. Mechanical characterization revealed similar hardness distribution across the Gleeble and HFIW welds. Notably, bond line oxide inclusions, such as those found in HFIW tubes, were also observed in the simulated welds. The effects of these inclusions on tensile properties and fracture mechanisms in industrial and simulated welds were determined, and ideal conditions for producing oxide-free welds to ensure superior weld mechanical properties were determined.