Electron Beam Processing of SensorsRelevant Vacoflux-49 Alloy: Experimental Studies of Thermal Zones and Microstructure

Vacoflux-49 (Fe-49% Co-49% V-2%) is used in torque, sonar and gyroscopic sensors applications due to excellent magnetic properties (high saturation magnetisation, low coercivity and high Curie temperature). In this study, the shape, size and characteristics of different thermal zones and the microstructural evolution during electron beam melting and welding of Vacoflux-49 material are studied. The experimental studies on melting have been carried out with under-focussed, focussed and over focussed electron beam. In the case of the under-focussed and over-focused beam, no evaporated zone is found. In the case of focussed beam, a shallow conical-shaped evaporated zone, a choked funnel-shaped fusion zone, a conical shaped partially melted zone and the heat-affected zone are observed. The solidified melt pool in terms of shape, size and microstructure of different zones are investigated for the focussed beam. The grains in the fusion zone appear wavy having crest and trough. The fusion zone microstructure also shows the formation of solidification rings. From the electron beam welding experiments performed for joining two Vacoflux-49 plates (continuous welding), it is found that the weldment shape is similar to the spot melting and re-solidification experiments. The grain growth in different zones in the welding sample is also examined