Search for: All records

This work describes the utilization of applied transverse magnetic fields to influence the arc dynamics during laboratory and industrial VAR melting. The arc motion was monitored with VARmetricTM as an external sensing platform to inform the system on the resultant direction and magnitude of the arcs due to the applied transverse magnetic field. Electromagnetic coils were mounted outside of the VAR in order to produce the near-uniform transverse magnetic field inside the furnace. These fields interact with the arc in a precise and measurable way, providing a control mechanism for arc motions and distributions. Results are provided for conditions where the applied fields were chosen such that the resultant force forces the arcs into non-ideal distributions, replicating potential deleterious operating conditions that could lead to defects. Results at both laboratory and industrial scale are provided and, wherever possible, ingots were sectioned, and the resulting grain structures were analyzed for defects. 

This work describes the utilization of applied transverse magnetic fields to influence the arc dynamics during laboratory and industrial VAR melting. The arc motion was monitored with VARmetricTM as an external sensing platform to inform the system on the resultant direction and magnitude of the arcs due to the applied transverse magnetic field. Electromagnetic coils were mounted outside of the VAR in order to produce the near-uniform transverse magnetic field inside the furnace. These fields interact with the arc in a precise and measurable way, providing a control mechanism for arc motions and distributions. Results are provided for conditions where the applied fields were chosen such that the resultant force forces the arcs into non-ideal distributions, replicating potential deleterious operating conditions that could lead to defects. Results at both laboratory and industrial scale are provided and, wherever possible, ingots were sectioned, and the resulting grain structures were analyzed for defects. 

Ampere Scientific has previously developed and provided industrial validation of the VARmetricTM measurement system to measure the location of electric arcs during vacuum arc remelting (VAR) of high temperature specialty alloys. With the advent of VARmetricTM, it is nowpossible to continuously monitor and control arc distributions in order to tailor the heat flux that drives solidification during the VAR process. Laboratory experiments have applied transverse magnetic fields to generate specified Lorentz forces as a control mechanism across the arc gap in order to drive arc locations to predetermined distributions. This type of control makes it possible to react to undesirable arc conditions during VAR operations or to provide a continuous control to specify a thermal profile for heat input to the melt pool necessary for ensuring defect-free ingots.