Search for: All records

The behavior of vacuum arcs during VAR processing is known to impact product yield and contribute to ingot defects. For example, it has been shown that constricted arcs during the processing of segregation prone nickel-based alloys can lead to defects in ingots. Despite this knowledge, the role of arc distributions in VAR processing has not been considered in controlling the furnaces. In addition, computational models of the process have typically assumed that the arc provides an axisymmetric, Gaussian heat input to the ingot, while acknowledging that this is the biggest unknown variable. Here we present the theory behind VARmetricTM and present analyses of the spatio-temporal arc distributions measured on a production VAR furnace. We then use the measured axisymmetric arc distributions to provide updated boundary conditions for solidification of the ingot to investigate the implications of the changing distributions on solidification and the relationship between arc distributions and defects.