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Magnetic measurements coupled with traditional VAR process measurements have enabled the characterization of the spatial distribution of electrical current through the furnace; a process variable that today’s VAR furnaces do not measure. This work presents data acquired by VARmetric, a high density magnetic sensor array, on an industrial VAR furnace processing Fe and Ni- based alloys. VARmetric is used to identify events which would go undetected through traditional process signal analysis, and importantly, can be used to distinguish between distinct arc modes, e.g. diffuse arcs, constricted arcs, and glows. This information facilitates a new method to assess the quality of an ingot in terms of the probability of segregation defects along the ingot axis. 

Magnetic measurements coupled with traditional VAR process measurements have enabled the characterization of the spatial distribution of electrical current through the furnace; a process variable that today’s VAR furnaces do not measure. This work presents data acquired by VARmetric, a high density magnetic sensor array, on an industrial VAR furnace processing Fe- and Ni- based alloys. VARmetric is used to identify events which would go undetected through traditional process signal analysis, and importantly, can be used to distinguish between distinct arc modes, e.g. diffuse arcs, constricted arcs, and glows. This information facilitates a new method to assess the quality of an ingot in terms of the probability of segregation defects along the ingot axis. 

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.