Publications Details
The effect of process perturbations on the local thermal environment in VAR alloy 718
Melt pool shape in VAR is controlled by fluid flow, which is governed by the balance between two opposing flow fields. At low melt currents, flow is dominated by thermal buoyancy. In these instances, metal is swept radially outward on the pool surface, resulting in relatively shallow melt pools but increased heat transfer to the crucible at the melt pool surface. At high melt currents, flow is primarily driven by magento-hydrodynamic forces. In these cases, the surface flow is radially inward and downward, resulting in a constricted arc, the pool depth and relative heat transfer to the crucible are intermediate, even though the melt rate is significantly lower than either diffuse arc condition. Constricted arc conditions also result in erratic heat transfer behavior and non-uniformities in pool shape.