Electric arc furnaces and vacuum arc remelting furnaces are used to melt and refine special alloy metals and superalloys. Secondary melting processes like electro slag remelting and vacuum arc remelting are used to produce cleaner alloys with less gas and improved properties. Forgings and rolling are further metal forming processes used to produce parts for applications like aerospace, defense, and automotive. Wire drawing is also used to produce flexible metal wires.

2. INTRODUCTION
• Mishra Dhatu Nigam Limited (MIDHANI) is
one of the modern and integrated
metallurgical plants for manufacturing a wide
range of special metals and alloys .
• These are used in industries like Nuclear
Power, Defence, Aeronautics, Automobile,
Electrical, Telecommunications,
Petrochemicals.
• Titan26A,Superni718A,E16NCD13 Alloy steel.

3. ELECTRIC ARC FURNACEPrimary melting is the first and main shop
where raw material are melted and refined to
some extent.

4. • Electric Arc Furnace is a furnace that heats the
charged material by mean of an electric arc.
• EAF consists of refractory lined vessel through
which one or more electrodes enter the
furnace.
•

5. ADVANTAGES
• EAF allows steel to be made from 100% scrap
metal feedstock.
• Flexibility is another advantage.

6. SECONDARY MELTING:
• Many alloys contain elements like aluminum and titanium which, when
heated, react with oxygen to form oxides. Oxides are detrimental to
premium quality melted alloys.
• Premium grade alloys, such as those required by the aerospace, energy,
medical and automotive industries, can be protected from the
atmosphere and residuals by melting inside a vacuum container.
• This approach gives the metals producer more control over alloy
chemistry.
• The result is a cleaner, more uniform product with the superior properties
required for critical service application.

7. Main objectives of secondary melting:
• To produce alloy with less amount of gases such as H2 , O2 and N2.
• To decrease the sulphur content by remelting the ingot.
• To finely disperse the inclusions.
• To ensure directional solidification.
There are two types of secondary melting furnaces
Electro slag remelting furnace(ESR).
Vacuum arc remelting furnace(VAR).

8. ELECTRO SLAG RE-MELTING :
Principle:
• Remelting is carried out under a reactive slag (flux).
• The heat is generated by the electrical resistance of the slag.
• The slag facilitates refinement in chemical composition and non metallic
inclusions in the ingot.
• Melting is carried out in water cooled copper crucible to obtain sound ,
homogeneous, directionally solidified and segregation free ingot.
• In this process slag is used as refining agent. The composition of slag is
• CaF2 : 60%
• Al2O3: 20%
• CaO : 20%

9. ESR FURNACE:

10. Alloys being melted
• Low and high alloy, high strength steels for armament, nuclear, and
aeronautical applications.
• Nickel and iron base super alloys for engineering applications.
Advantages :
• Refined metal can be obtained.
• Good surface finish obtained than in VAR ( vaccum arc remelting furnace).
• Homogeneity in production.
• High degree of cleanliness.
• Free of internal flaws (eg: hydrogen flakes).

11. VACUUM ARC REMELTING FURNACE(VAR)
Principle:
The main principle in this furnace is when a high amperage low
voltage direct current is employed, for striking an arc between the
consumable electrode and a pad of steel placed in the bottom of the
copper mould. The arc gap is automatically maintained.
Improvements carried out in melting practice:
• Helium cooling of super alloys ingots during solidification.
• Introduction of computer control for melt rate.
• Improvement in the design of crucible clamping system.
Alloys being melted:
• Super alloys for aeronautical as well as engineering applications .
• Special steels for space , aeronautical and nuclear applications.
(e.g. Maraging steels, PH stainless steels, Titanium stabilized stainless
steels ect).

12. VACUUM ARC REMELTING FURNACE(VAR)

13. ADVANTAGES:
• Low hydrogen content.
• Low gas content.
• Cleanliness in operation.
• Homogeneity in production.
• No foreign inclusions, as there is no refractory.

14. VIM
• VIM is used to melt the metal under vaccum
by using electromagnetic induction.
• It is used for refining of high purity metal and
alloys .
• VIM melted alloys are used in very demanding
situations like Ni base super alloys and cobalt
base super alloy.

15. FORGING
• Forging is manufacturing process .
• It is often classified to the temperature which
it is performed.
• Forged parts ranges from less than a kilogram
to 580 metric ton.
• They require furthur processing to achieve
finished part.

16. • Different forging operations are available
mainly drawn out & upset.
• In midhani open die forging is carried out
effectively.
• There are 2 types of furnaces in forge shop:
• Fixed hearth and
• Bogie hearth furnace

17. ROLLING
• It is a metal forming processs in which metal
stock is passed through a pair of rolls .
• If Temp of the metal is above recrystallization
temp than it is hot rolling.

18. • Sheet mill, strip mill, bar mill, wire rod mill.
• ADVANTAGES:
• Uniformity of metal qualities i.e dimension,
profile & microstructure.
• Hot strip with thickness under 0.8mm can be
produced.

19. • cold working process allow desirable metal
qualities that cannot be obtained by hot
working.
• Such as more compact & high dimensional
accuracy etc.
• Machines available in midhani is 6HI COLD
SHEET MILL,12HI COLD STRIP MILL.
DISADVANTAGE :More brittle.
APPLICATION : Electric motors, commercial
doors.

20. WIRE DRAWING
• It is used to produce flexible metal wire by
drawing the material through series of dies.
• Dies used are tungsten carbide and diamond.