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Vacuum Arc Remelting (VAR)

Vacuum Arc Remelting (VAR)

Product catalog summary

Introduction to Vacuum Arc Remelting (VAR):
VAR is a process involving the continuous remelting of a consumable electrode using an arc under vacuum conditions. This process is crucial for producing high-integrity materials with improved cleanliness and refined structure, essential for industries like aerospace, power generation, and medical sectors.

Process Technology and Characteristics:
The VAR process involves striking a DC arc between an electrode and a copper mold baseplate, generating intense heat to melt the electrode tip and form a new ingot. The process is maintained under high vacuum to ensure quality. Modern VAR furnaces have advanced with computer controls for automatic remelting, enhancing reproducibility of metallurgical properties.

Metallurgy of the VAR Process:
The solidification structure of VAR ingots depends on the local solidification rate and temperature gradient. Optimal results are achieved with dendrites parallel to the ingot axis, although defects like tree ring patterns, freckles, and white spots can occur, affecting material properties.

Defects and Their Mitigation:
Tree ring patterns, freckles, and white spots are common defects. Freckles and white spots significantly impact material properties and can lead to premature failure. Mitigation involves controlling remelting rates, arc stability, and using homogeneous electrodes.

Process Control:
Close control of remelting parameters is essential for producing homogeneous ingots. Computer-controlled automation systems manage process parameters, ensuring reproducibility and quality. Established parameters are stored as remelting recipes for consistent production.

Advantages of VAR:
VAR offers benefits like removal of dissolved gases, reduction of trace elements, improved oxide cleanliness, and directional solidification, reducing segregation.

VAR Features and Applications:
VAR furnaces can handle ingot diameters up to 1,500 mm and weights up to 50 tons. Applications include superalloys for aerospace, high-strength steels, ball-bearing steels, tool steels, and reactive metals for various industries.

Contact Information:
ALD Vacuum Technologies has offices in the UK, USA, Germany, China, and Japan, providing global support for VAR technology.

Catalog excerpts

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table.main {} tr.row {} td.cell {} div.block {} div.paragraph {} .font0 { font:11.00pt "Impact", sans-serif; } .font1 { font:13.00pt "Impact", sans-serif; } .font2 { font:29.00pt "Impact", sans-serif; } Vacuum Arc Remelting (VAR) HR is widely used 1o improve the cleonliness and refno the structure of standard airmelted or vocuum induction mehed ingofs, then colled consumoble lectrodes. VAR steels and tuptrolloys as well as tilanium and zirconium and ifs alloys are used in a great number o( high-integrity applications wttere cleanlmess, homogenerty, improved fatigue ond fracture loughness of the...

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table.main {} tr.row {} td.cell {} div.block {} div.paragraph {} .font0 { font:11.00pt "Impact", sans-serif; } .font1 { font:13.00pt "Impact", sans-serif; } Metallirgy of the Vacuum Arc Remelting Process The VAR ingot's solidification structure ot a given matriel h o fundion of the locof solidf鯯calion rate ont) the temprature gradient at the liquid/solid interface. Ta achieve a direcled dendrrtfc primary structure, a relolively high temprature gradient at the solidification front must be moinloined during the entire remelting process. The growlh direction of the cellular dendrites conforms 1o...

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table.main {} tr.row {} td.cell {} div.block {} div.paragraph {} .font0 { font:11.00pt "Impact", sans-serif; } .font1 { font:68.00pt "Impact", sans-serif; } ■ Ff eckles ond white spots hove o much greoler effect on materiol properties as compared to Iree ring potterns. Both defects con represent o signifkant cause for prmatur foilure of turbine disks in aircraft engines. Freckles are dark-etching circuler or nearly circulor spots tha驯 are generolly rich in cor bides or carbide forming lments. The formation of freckles is usuolly a resuit of a high metol pool rfepth and somefimes of a rotating...

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table.main {} tr.row {} td.cell {} div.block {} div.paragraph {} .font0 { font:10.00pt "Impact", sans-serif; } .font1 { font:11.00pt "Impact", sans-serif; } .font2 { font:13.00pt "Impact", sans-serif; } Process Control Clote control of ail remelling paromelers is required for reproduable production of homogeneous ingots, which ore free of mocrosegregation ond show o controlled solidification structura and superior cleanliness. To fulfill todoy's most stringent molerial quality spcifications, VAR furnects make use of computer controlled process outomalion. Logic control fondions, continuous weighing...

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