PSI - Issue 81

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

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3. Results and Discussion The appearance of the remelted ingots is shown in Fig. 2. In all cases, the layers of the deposited metal are clearly visible on the ingot side surface, with characteristic interlayer grooves between them. The depth of these grooves depends on the ingot diameter d in , the duration of the melting pauses t pU , and the electrical parameters of metal pool heating U p , I p . In all experiments, except for Experiment No. 6, the groove depth did not exceed 1 – 2 mm, which indicates good quality of the ingot’s side surface formation. In Experiment No. 6, the groove depth reached 3– 5 mm. This was caused by insufficient power of the molten metal heating during electrode melting pauses, combined with the long duration of these pauses (600 s). In Experiment No. 7, with the same pause duration ( t pU = 600 s), an increase in the heating power by 43 % led to a reduction in interlayer groove depth to 1.5 – 2 mm. In general, the analysis of the obtained results indicates that, under pulsed ESR conditions, it is possible to maintain high quality formation of the ingot’s side surface, without rough interlayer grooves or other surface defects.

Fig. 2. Formation of the ingots side surface (numbers indicate the experiments No.)

Figure 3 shows the as-cast structure of the 54Fe-29Ni-17Co alloy ingots. It can be seen that the layer-by-layer formation significantly influences the solidification pattern of the ingot. This approach provides wide opportunities for controlling the metal's structure. While under conventional ESR the cast structure consists of large, radially oriented columnar crystals with a zone of opposite crystallization along the ingot axis (Fig. 3, No. 1), pulsed ESR makes it possible to achieve significant refinement and homogenization of the metal structure (Fig. 3, No. 3). With insufficient duration of the melting pauses, which determine the volume of the solidified portion of the deposited metal, transcrystallization is preserved in the central part of the ingot (Fig. 3, No. 2, 4). This indicates the need to adjust this parameter to reduce the layer of liquid metal prior to depositing the next portion of metal and to suppress transcrystallization. In general, 54Fe-29Ni-17Co alloy ingots produced by pulsed ESR exhibit a misoriented structure without an axial zone of opposite crystallization, and their structural dispersion is significantly higher compared to conventional ESR (Table 2). Furthermore, no metallurgical defects such as pores or nonmetallic inclusions were detected in the 54Fe-29Ni-17Co alloy ingots.

Fig. 3. Cast structure of 54Fe-29Ni-17Co alloy ingots (numbers indicate the experiments No.)