PSI - Issue 81

Igor Protokovilov et al. / Procedia Structural Integrity 81 (2026) 156–161

160

Fig. 5. Effect of layer height on grain size

The experiments made it possible to develop a set of recommendations for the layer-by-layer formation modes of ESR ingots with a diameter of up to 220 mm (Fig. 6). The height of individual portions of the deposited metal should preferably be within the range of (0.1 –0.5) × d in . This ensures refinement of the metal structure while maintaining good quality of the ingot’s side surface without rough interlayer grooves . It is essential that during the layer-by-layer formation process, a layer of molten metal remains on the ingot top surface at all times. Based on this, the duration of pauses should be selected so that during this time 75 – 95% of the volume of the metal pool solidifies. If a smaller volume of the pool solidifies, the efficiency of structural refinement decreases, and transcrystallization persists in the central region of the ingot. If a larger volume solidifies, defects may form along the interlayer boundaries (Fig. 6). It is important that during electrode melting pauses, an electric current continues to flow through the metal pool, providing heating of the slag – metal interface. This prevents the formation of a crust of solidified metal on the pool surface. The heating power should be chosen according to the alloy composition, flux grade, and ingot dimensions. The increase in power when switching from melting pauses to melting periods should be carried out smoothly. It should be noted that the choice of specific layer-by-layer formation parameters depends on the alloy grade being melted and the ingot dimensions. The use of optimized regimes will yield positive effects in the form of homogenization and refinement of the ingot's cast structure.

Fig. 6. Cast structure evolution depending on the parameters of pulsed mode ESR

4. Conclusion The conducted experiments demonstrated the feasibility of conducting the ESR process in a pulsed mode, which ensures layer-by-layer growth of the ingot. This is achieved through periodic variation of process power, leading to cyclic melting of the consumable electrode and solidification of the ingot along its height. It was established that pulsed-mode ESR enables control of the metal structure and allows production of ingots with a finer structural dispersion compared to conventional ESR. This makes it possible to avoid the formation of different structural zones across the ingot cross-section and the development of large columnar crystals with a zone of opposing crystallization at the ingot axis. The study defined the basic principles for controlling the cast structure during pulsed-mode ESR and provided recommendations for layer-by-layer formation of ingots up to 220 mm in diameter with enhanced structural homogeneity. This process can be effective for ESR of complex alloy systems such as precision alloys, nickel-based superalloys, titanium alloys, and others.