Ce diaporama a bien été signalé.
Nous utilisons votre profil LinkedIn et vos données d’activité pour vous proposer des publicités personnalisées et pertinentes. Vous pouvez changer vos préférences de publicités à tout moment.

Electroslag melting and refining

2 530 vues

Publié le

casting new technology

Publié dans : Ingénierie
  • Soyez le premier à commenter

Electroslag melting and refining

  1. 1. AMRITA SCHOOL OF ENGINEERING, COIMBATORE PRESENTED BY: SABIQ (CB.EN.P2MFG15017) SANDEEP NAIR (CB.EN.P2MFG15018) M.TECH (MANUFACTURING ) ELECTROSLAG MELTING AND REFINING
  2. 2. INTRODUCTION  This process was developed originally in the erstwhile USSR in 1930.  Electro-slag melting is also known as Electro-flux melting is a process of melting and refining steel and super alloys for mission critical application.  It principle is based on the electro-slag welding process.  It dispenses completely with the rising and gating system and also with the need for separate melting unit ,pouring ladle and transportation arrangements.  Graphite and ceramic mould has been used in place of metallic ones.  Consumable steel electrodes are used.
  3. 3. ELECTROSLAG MELTING FURNACES
  4. 4. WORKING OF ESM FURNACE  The electro-slag melting process is used to melt and refine steels and various super-alloys, resulting in high quality ingots.  Electric current (generally AC) is passed between the electrode and new ingots ,which is formed in the bottom of a water-cooled copper mold.  The new ingot is covered in a engineering slag that is superheated by the electric current.  These metal droplets travels through the slag to the bottom of the water cooled mold and slowly freeze as the ingot is directionally solidified upwards from the bottom of mold.
  5. 5.  Solidification takes place without any contact with the atmosphere.  The slag pool floats above the refined alloys, continuously floating upward as the alloy solidifies.  The molten metal is cleaned of impurities that chemically react with slag or otherwise float to the top of the molten pool as the molten droplets pass through the slag's.  Electro-slag melting uses highly reactive slags to reduce the amount of sulfide present in bio-metal alloys.  ESM furnaces can be designed for melting of round, square and rectangular (slab) ingots. WORKING OF ESM FURNACE
  6. 6. SLAG USED AND ITS PROPERTIES  Slag for electro-slag melting 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 melted.  To perform its intended functions, the slag must have some well-defined properties, such as:- 1). Its melting point must be lower than that of the metal to be melted. 2). It must be electrically efficient. 3). Its composition should be selected to ensure the desired chemical reactions. 4). It must have suitable viscosity at melting temperature.
  7. 7. ESM PROCESS INVOLVES FEWER STEPS THAN SAND CASTING FABRICATE PATTERN SPLIT MOLD FLASK SPLIT FLASK REMOVE PATTERN INERT CORE ASSEMBLE MOLD BAKE CENTRIFUGAL OR GRAVITY SHAKE OUT TRIM GATE AND RISER SURFACE CLEAN HEAT S A N D C A S T I N G FABRICATE MOLD ADD SLAG ELECTROSLA G CAST REMOVE FROM MOLD SURFACE CLEAN GRIT BLAST MACHINE TOP HEAT TREAT E L E C T R O S L A G M E L T I N G
  8. 8. PROCESS  No removal of hydrogen and nitrogen.  Minimum sulphur content due to slag reaction.  Smooth surface due to slag skin on surface.  Less material defect due to melting of dendrite clumps  Electrode can be used in cast condition due to cleaning by slag.  Melt rate choose to slag skin equal to dendrite arm spacing.  No manganese losses in alloys.
  9. 9. KEY FEATURES  Ingot weights from 100 kg to 165 metric tons.  Alternating current as re-melting energy with melting currents from 3 ka to 92 ka.  Ingot diameters from 170 mm to 2,300 mm, depending on material being melted.  Circular, square and rectangular ingot shapes are possible.  Surface electrode preparation normally not ground.  Melting effect on gas content - constant nitrogen and hydrogen.  Melting rate-13kg/min  No modification ; maximal homogeneity.  Casting yield is almost 100%.
  10. 10. NEW DEVELOPMENT IN ESM PROCESS Electro-slag melting under Vacuum (VAC-ESM):  Melting is carried out under vacuum as in VAR, however, using a slag. Problems of oxidation of the melt do not arise. In addition, dissolved gases such as hydrogen and nitrogen, can be removed . The danger of white spots, as encountered during VAR, is reduced to a minimum. That is of interest for super-alloys or titanium melting. Low gas content in final material ,then VAR process is chosen.
  11. 11. MELTING UNDER INERT GAS ATMOSPHERE (IESM):
  12. 12. MELTINGUNDERINERTGASATMOSPHERE (IESM):  This is a great step forward in freeing the ESM process from hydrogen pick-up problem and the influence of seasonal atmospheric changes. In addition it allows melting under oxygen-free inert gas. The following results have been obtained:-  Oxidation of electrode and slag is completely avoided;  Oxidizing loss of elements such as Ti, Zr, Al, Si, etc. is almost completely avoided.
  13. 13. MELTINGUNDERINERTGASATMOSPHERE (IESM):  This is especially important when melting high Al and Ti-containing alloys, like super- alloys with very narrow analytical ranges:- 1). Better cleanliness in the ingot is achieved. 2). When using argon as the inert gas, pick-up of nitrogen and hydrogen is avoided.  Due to the absence of oxygen in the furnace atmosphere, desulfurization via the gas phase is no longer optimal.
  14. 14. PROCESSCHARACTERISTICSINMELTING
  15. 15. CHEMICAL ELEMENT CHANGE IN MELTING
  16. 16. ADVANTAGES 1) Uniform mechanical properties in the longitudinal and sectional direction. 2) Very large ingots such as 3000mm diameter and more than 200ton weight can be produced. 3) Homogeneous, sound and directionally solidified structure. 4) High degree of cleanliness. 5) Free of internal flaws (e.g. hydrogen flakes). 6) Free of macro-segregation. 7) Smooth ingot surface resulting in a high ingot yield.
  17. 17. LIMITATIONS 1) Slag treatment to achieve lowest hydrogen in Ingot. 2) Closed melting to avoid hydrogen pick-up from atmosphere. 3) Melt rate adjusted according to slag system, alloy composition and furnace size. 4) Gases (like nitrogen & hydrogen) need to be adjusted to lowest level in the electrode. 5) Adjustment of slag chemistry and composition of the electrode.
  18. 18. APPLICATIONS AIRCRAFT
  19. 19. MILITARY TECHNOLOGY 1. Plug lid 2. Cardboard lid 3. Primer lid 4. Axis of firing pin 5. Spring 6. Firing pin 7. Leather circlet 8. Screw thread 9. Body of plug 10.Wick 11.Primer 2 12.Detonator 13.Primer 1 14.Bolt 15.Pin 16.Lever 17.overview
  20. 20. THERMAL POWER STATIONS
  21. 21. NUCLEAR POWER PLANTS
  22. 22. CONNECTING ROD
  23. 23. HIGH PRESSURE VESSELS
  24. 24. CRANKSHAFTS
  25. 25. MILLING CUTTERS
  26. 26. REFERENCES  New Technology of Electro slag Casting of Solid Horn- Shaped CoresE.N. Eremin,Omsk State Technical University, Omsk, Russia.  Materials Research and Engineering Edited by B. Ilschner and N.J. Grant.  Commercialization effort in support of electroslac- casting technology ,V. K. Sikka.  Principle of foundary technology, P.L. Jain

×