VIM Process & Equipment

Vacuum Induction Melting (VIM) is a high-end metallurgical technology for manufacturing high-purity, high-performance master alloys and precision metals. It realizes metal melting, temperature control and refining in a high-vacuum sealed chamber by medium-frequency induction heating, ensuring ultra-clean and composition-accurate products.

Our VIM equipment features a fully automated control system, multi-stage vacuum pump units, and high-temperature resistant crucibles, which can effectively remove harmful gases (H, O, N) to ppm level, inhibit the burning loss of volatile elements, and avoid secondary pollution. The whole process is automated with precise temperature control (±5℃) and stable process parameters.

Widely applied in aerospace (single-crystal/directional solidification superalloy master alloys), energy, military industry and high-precision manufacturing fields, our VIM process provides high-quality raw materials for subsequent VAR, ESR, directional solidification and single-crystal casting processes, supporting the production of high-temperature, high-precision and high-purity products.

Induction Heating: A medium-frequency induction coil is built into the furnace. When an alternating current is passed through it, an alternating magnetic field is generated, which induces eddy currents inside the metal materials (electrodes/master alloy ingots) in the furnace. Electrical energy is directly converted into internal thermal energy of the metal, achieving rapid melting (no electrode contact, no external pollution).

1. Vacuum Environment: The furnace chamber is evacuated to a high vacuum of 10-1~10-2 Pa.
2. Remove harmful gases: such as hydrogen, oxygen and nitrogen to greatly improve the purity of the alloy.
3. Inhibit the burning loss of volatile/oxidizable elements: such as Al, Ti, Zr, rare earths, to ensure precise composition.
4. Avoid oxidative inclusions and obtain ingots/master alloys with no pores and high density.
5. Refining and Casting: After melting, heat preservation and homogenization are performed, and the composition is fine-tuned, followed by directional casting of ingots, master alloy ingots and precision castings under vacuum/protective atmosphere.

• Lower gas and impurity element content

By controlling raw materials, auxiliary materials, smelting processes, and other aspects, the product can achieve:

O+N+S≤10ppm

Harmful impurity elements Pb+Sn+Sb+Bi+As+Se ≤ 5ppm

The total amount of over 40 trace elements, including Pb, Sn, Ag, Bi, As, Se, Tl, etc., is less than 50ppm

• More precise ingredient control

Ensure that the alloy composition of each furnace is qualified through In-furnace analysis and  Post-furnace analysis.

The furnace fluctuation of main elements such as Cr, Mo, W, Ta, etc. is controlled within ± 0.05%, and the furnace fluctuation of Al and Ti is controlled within ± 0.03%

The furnace fluctuation of trace elements such as C, B, Zr, etc. is controlled within ± 0.005%

• Less inclusion content

By innovating slag blocking and filtering technologies, the impurity content in the molten steel is controlled at the lowest level, and the remelted slag can reach zero level.

• Better performance

By optimizing the grain size, carbon content, carbide morphology, heat treatment, etc. of the alloy, the durability is improved by more than 60%, and the elongation is increased by 82%

• Aerospace: Single-crystal/directional solidification superalloy master alloys, turbine blade materials.
• Energy: Gas turbines, superalloys and corrosion-resistant alloys for nuclear power.
• Military Industry: Precision casting, special alloys, high-purity metals.
• Medical: High-purity nickel alloy, cobalt alloy, non-magnetic/corrosion-resistant precision materials.