| Abstract Scope |
High-frequency electric resistance welding (HF-ERW) is used to manufacture longitudinal seam welded steel linepipe of diameter less than 24 inches. In HF-ERW, heat is generated by resistance to the flow of electric current applied by induction or conduction. Subsequently, the steel edges are mechanically pressed together to form a solid-state bondline, effectively expelling any melted material. Physical simulations on the Gleeble were not able to replicate the characteristic HF-ERW thermal and deformation histories of the industrially manufactured joints. A novel physical simulation system that consists of a high-frequency induction heating unit, an MTS servo-hydraulic load frame, and a closed-loop temperature controller, has been designed and developed to faithfully reproduce HF-ERW joints. A comparable microstructure is successfully simulated along with the typical hourglass shape of the heat affected zone of an industrial HF-ERW joint. Physical simulation experiments have been performed in both the displacement-controlled and force-controlled conditions with varying process parameters, such as force, temperature, strain, and strain rate. The measured force response from the physical simulation experiments is modeled using the force balance equation during the bond formation. In addition, a coupled electromagnetic and thermal finite element model has been developed to understand the heating and compression operations on bond formation mechanisms. |