Electroslag Remelting (ESR)
8Pages

EB_2011.qxd table.main {} tr.row {} td.cell {} div.block {} div.paragraph {} .font0 { font:12.00pt "Impact", sans-serif; } .font1 { font:25.00pt "Impact", sans-serif; } Electroslag Remelting (ESR) Electroslag Remelting Processes and Furnaces

EB_2011.qxd table.main {} tr.row {} td.cell {} div.block {} div.paragraph {} .font0 { font:6.00pt "Impact", sans-serif; } .font1 { font:9.00pt "Impact", sans-serif; } .font2 { font:18.00pt "Impact", sans-serif; } 2 Electroslag Remelting ESR has been known since the 1930s, but it took approx. 30 years before it became an acknowledged process for mass production of high-quality ingots. The ESR technology is of interest not only for the production of smaller weight ingots of tool steels and superalloys, but also of heavy forging ingots up to raw ingot weights of 165 tons. Process Technology...

EB_2011.qxd table.main {} tr.row {} td.cell {} div.block {} div.paragraph {} .font0 { font:7.00pt "Arial", sans-serif; } .font1 { font:6.00pt "Impact", sans-serif; } .font2 { font:9.00pt "Impact", sans-serif; } 3 Slags for ESR are usually based on calcium fluoride (CaF2), lime (CaO) and alumina (Al2O3). Magnesia (MgO), titania (TiO2) and silica (SiO2) may also be added, depending on the alloy to be remelted. To perform its intended functions, the slag must have some well-defined properties, such as: ■ Its melting point must be lower than that of the metal to be remelted; ■ It must be...

EB_2011.qxd table.main {} tr.row {} td.cell {} div.block {} div.paragraph {} .font0 { font:6.00pt "Impact", sans-serif; } .font1 { font:9.00pt "Impact", sans-serif; } 165 ton ESR furnace. A fully coaxial furnace design is required for remelting of segregation-sensitive alloys in order to prevent melt stirring by stray magnetic fields. Shielding of the melt space with protective atmosphere has been the latest trend in recent years. Remelting under increased pressure to increase the nitrogen content in the ingot is another variation of ESR. ESR furnaces can be designed for remelting of round,...

EB_2011.qxd table.main {} tr.row {} td.cell {} div.block {} div.paragraph {} .font0 { font:6.00pt "Impact", sans-serif; } .font1 { font:9.00pt "Impact", sans-serif; } 5 Directional solidification must be ensured over the entire ingot cross-section and length to avoid interior defects, such as macrosegregation, shrinkage cavities and nonuniform distribution of inclusions. By maintaining the correct remelting rate and slag temperature, directional solidification can be achieved for ingot diameters as large as 2,300 mm. Accordingly, the ESR ingot is free from macro-segregation in spite of the...

EB_2011.qxd table.main {} tr.row {} td.cell {} div.block {} div.paragraph {} .font0 { font:6.00pt "Impact", sans-serif; } .font1 { font:8.00pt "Impact", sans-serif; } .font2 { font:9.00pt "Impact", sans-serif; } Remelting under Inert Gas Atmosphre (IESR) As a consquence of ALD's development work in PESR processing, ALD nowadays recommends to conduct the ESR process under a fully enclosed inert gas atmosphere at atmospheric pressure. This is a great step forward in freeing the ESR process from hydrogen pick-up prob-lem and the influence of seasonal atmospheric changes. In addition it allows...

EB_2011.qxd table.main {} tr.row {} td.cell {} div.block {} div.paragraph {} .font0 { font:6.00pt "Impact", sans-serif; } .font1 { font:8.00pt "Impact", sans-serif; } .font2 { font:9.00pt "Impact", sans-serif; } 7 Furnace Types ALD has developed five basic ESR furnace concepts: Pilot Systems for stationary and moving mold applications. These are particularly well-suited for experimental and pilot production, and for the perͭformance of high-versatility ESR operation at low investment cost. Stationary Mold Systems with two fixed remelting stations and one piv-oting furnace head. These are...

EB_2011.qxd table.main {} tr.row {} td.cell {} div.block {} div.paragraph {} .font0 { font:5.00pt "Arial", sans-serif; } .font1 { font:6.00pt "Arial", sans-serif; } .font2 { font:7.00pt "Arial", sans-serif; } .font3 { font:8.00pt "Arial", sans-serif; } .font4 { font:6.00pt "Impact", sans-serif; } .font5 { font:8.00pt "Impact", sans-serif; } .font6 { font:9.00pt "Impact", sans-serif; } .font7 { font:38.00pt "Impact", sans-serif; } Pressurized / Vacuum Systems Completely sealed Systems for ESR oprations under vacuum, inert gas, or increased pressure. These systems are particularly suited for...