Remelts

Remelts are metallurgical operations in which metal or alloy that has already solidified is melted again to produce refined feedstock or finished ingots. The objective is to improve chemical homogeneity, reduce nonmetallic inclusions, and achieve precise control of composition and microstructure, which are important for high-performance applications. Remelted materials are widely used in aerospace, power generation, and electronics, particularly nickel-based superalloys, titanium alloys, stainless steels, and other specialty steels.

Common remelting methods include Vacuum Arc Remelting (VAR) and Electroslag Remelting (ESR). VAR melts a consumable electrode in a water-cooled crucible under high vacuum, helping remove volatile impurities and promote a purer ingot with directional solidification. ESR uses a consumable electrode that melts through a molten slag layer, refining the metal and removing inclusions before it is cast. Induction remelting and other furnace-based approaches are used for recycling scrap or producing economical feedstock, sometimes in continuous or semi-continuous forms.

Process variables include charge material (virgin alloy, scrap, or preforms), atmosphere or vacuum level, temperature control, and solidification rate. Slag composition is critical in ESR, while vacuum quality matters in VAR. The resulting product is typically an ingot or refined billet that can undergo further forging, rolling, or heat treatment.

Benefits of remelting include improved cleanliness, chemical uniformity, and mechanical properties suitable for demanding service conditions. Drawbacks include higher energy consumption, greater equipment cost, and longer production cycles; not all alloys require or benefit equally from remelting.