THE INFLUENCE OF ELECTRODE REPLACEMENT PARAMETERS AND MELT RATE ON THE QUALITY OF INCONEL 625 INGOT DURING ELECTROSLAG REMELTING WITH ELECTRODE REPLACEMENT

Abstract

This paper presents experimental results from a study of the electroslag remelting (ESR) of the highly alloyed nickel-based superalloy Inconel 625, carried out using a sequence of four consecutive consumable electrodes within a single melt. The experimental melts were conducted on an industrial ESR-9.8 unit (JSC Ruspolymet) utilizing a short 300 mm diameter mold and ESR2060 flux. The objective was to evaluate the influence of the melting rate and the duration of technological pauses associated with electrode changes on the macrostructure formation, distribution of alloying elements, and ingot side surface quality. The melting rate was varied stepwise in the range of 180–220 kg/h. The tungsten marker method was employed to maintain the configuration of the metal bath during transient phases. Metallographic analysis of the junction zones corresponding to the electrode change moments was performed. It was experimentally confirmed that increasing the remelting rate to 220 kg/h prevents the formation of surface defects in the conjugation zones, which are characteristic of lower productivity regimes. It has been established that the depth of the liquid pool was found to increase by no more than 3–6% after process resumption relative to depth before the pause. Chemical analysis data indicate that varying the rate within the investigated range does not cause significant segregation of chromium, molybdenum, or niobium, concurrently, the sulfur content is reduced from 0.004% in the initial electrode to 0.001% across all ingot zones, indicating the high refining capacity of the process. Based on the obtained data, rational processing parameters were determined, enabling the production of high-quality Inconel 625 ingots under conditions of multiple electrode replacements.