Brief info about shops in midhani.

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.