3 smelting processes for nickel-based alloy：VIM, ESR and VAR

Nickel-based alloys refer to a class of alloys with comprehensive properties such as high strength and certain oxidation and corrosion resistance at high temperatures of 650 to 1000 °C, including nickel-based heat-resistant alloys, nickel-based corrosion-resistant alloys, and nickel-based wear-resistant alloys. , nickel-based precision alloys and nickel-based shape memory alloys. They all have very important applications, such as nickel-based superalloys, which are commonly used in the manufacture of aero-engine blades and rocket engines, nuclear reactors, energy conversion equipment, etc., serving high-end fields of aviation, power generation, defense, medical and nuclear industries.

Due to the high melting point of nickel alloys and high requirements for their own purity, the smelting process of nickel-based alloys is different from conventional smelting methods, which is very unique. Wooden alloys are summarized as follows, and there are three main processes:

1. Vacuum induction melting (VIM)

Vacuum induction melting (VIM for short) is a method of smelting under vacuum conditions, using electromagnetic induction to generate eddy currents in metal conductors to heat the charge.

VIM provides maximum control over the chemical composition and prevents contact of the melt with atmospheric hydrogen, oxygen and nitrogen. Electromagnetic stirring can not only make the melt uniform, but also continuously bring the reactants to the melt and vacuum interface, so that the subsequent refining reaction can be carried out smoothly. The gas content and the volatilization and precipitation of non-metallic inclusions can greatly improve the mechanical properties of most superalloys.

VIM furnace is an important smelting equipment for the production of special alloy materials such as nickel-based superalloys and corrosion-resistant alloys. Especially for alloys containing many active elements such as aluminum and titanium, vacuum induction melting must be used.

2. Electroslag Remelting (ESR)

Electroslag remelting (Electro-Slag Remelting, ESR for short) is a method of smelting using the resistance heat generated when the current passes through the molten slag as a heat source. When the droplets fall, they pass through the slag layer and enter the molten metal pool, and then crystallize and solidify into a steel ingot in a water-cooled crystallizer. Electroslag metallurgy is an important means of producing high-quality materials at present. It combines high-temperature smelting, chemical refining and condensation crystallization to produce high-quality ingots with high purity, low sulfur content, few non-metallic inclusions, smooth ingot surface and uniform crystallization. The advantages of compactness, metallographic structure and uniform chemical composition are widely used in important fields of national economy such as aerospace, military industry, energy, shipbuilding, electronics, petrochemical, heavy machinery and transportation.

3. Vacuum consumable arc melting (VAR)

Vacuum consumable arc smelting (Vacuum Arc Remelting, referred to as VAR) is in a vacuum state, using a DC power supply to generate an arc between the electrode and the copper crucible bottom plate placed in the water jacket, the arc heating generates high heat, melting the electrode, and the electrode is continuously heated. Falling and melting, a molten pool is formed in a water-cooled copper crucible, and the molten metal is rapidly solidified, crystallized, and solidified into an ingot.

Vacuum arc melting is generally used for refining stainless steel, super alloys, titanium, zirconium, tantalum, tantalum, niobium, tungsten, and molybdenum and other easily oxidizable metals and alloys. Cleanliness, uniformity, fatigue resistance and fracture toughness, so the consistency and uniformity of its structure are better, the number of inclusions is small, and the purity of the alloy is further improved. Vacuum arc melting is ideal for melting special steels, reactive and refractory metals such as titanium, molybdenum, and niobium.

It is worth noting that most special materials such as high-quality superalloys and corrosion-resistant alloys at home and abroad do not use a single process, but a double or triple method, that is, through a vacuum induction furnace + electroslag remelting furnace ( VIM+ESR) or vacuum induction furnace+vacuum consumable furnace (VIM+VAR) for production, and there are also a small number of harsh industries such as military supplies (VIM+ESR+VAR) for production. 

Wudenalloy has focused on the production and manufacture of nickel alloys for more than 10 years. We are a principal worldwide supplier of corrosion-resistant alloys and other superalloy metals. We have a professional technical team and after-sales service, so we can offer high-quality Hastelloy, Incoloy, Inconel, Monel, Duplex Stainless Steel, and other alloy material. These materials are available in wire, bar, sheet&plate, pipe&tube, flange, forging, and other forms to meet the needs of our customers.

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