1. Hot rolling is a process where large metal pieces are heated and rolled into thinner cross sections between rollers. 2. The hot rolling process involves reheating slabs, descaling, roughing and finishing rolls to produce hot rolled coils. 3. Hot rolled coils have a wide variety of applications including tubes, pipes, automotive parts, general structures, and are used to make cold rolled coils and sheets.

1. WORLD OF STEEL
Presented By:-
Subhajit Karmakar.

2. What is HR Coils?
Hot rolling is a hot working metalworking
process where large pieces of metal, such as
slabs or billets, are heated above their re-
crystallization temperature and then
deformed between rollers to form thinner
cross sections.

3. Process at a Glance:-
PROCESS AT A GLANCE

4. Manufacturing Process:-
1. The Hot Rolling Process:-
The starting material is usually large pieces of metal,
like semi-finished casting products, such as slabs, blooms, and
billets.
In continuous casting, rolling mill is mostly integrated to save
energy.
for larger work pieces gas- or oil-fired soaking pit
for smaller work pieces induction heating.
a finishing temperature is defined (50 to 100 C above the
recrystallization temperature) If the temperature does drop
below this temperature the material must be re-heated before
more hot rolling.

5. 2. Reheating
Critical to the Hot Strip Mill is its walking-beam reheat furnace,
state-of-the art equipment that replaced and now outperforms three
older- (pusher-) style furnaces.
3. Descaling
After exiting the reheat furnace, the slab passes through a descaling
unit, an enclosure employing two pairs of
spray headers that blast the intensely hot slab with 1,500 psi
pressurized water to remove the 1/8-inch thick layer
of oxidized iron that forms at the surface of the slab in the oxygen-
rich atmosphere of the reheat furnace.
4. Roughing
The roughing mill is made up of six independent rolling mill stands,
the last four of which incorporate small
vertical rolling mills called edgers. Slabs heated in the furnace until
they glow bright orange-yellow are rolled
through one stand at a time to produce so-called transfer bars
suitable for finish rolling.

6. Contd…
Approximately 96% of steel is continuously cast (the
remaining - ingots ).
After hot rolling the cooling should be done uniformly else
residual stress is generated due to shrinkage that affects
the mechanical properties.
Mill scale is the oxide layer formed on the surface due to
reaction with atmosphere at high temperatures.
Pickling is done with HCl to remove this scale.

7. 5. Edging
At the very high temperatures at which the steel is rolled in the
roughing mill, it is very plastic and ‘flows’ easily like cookie dough
beneath a rolling pin. Consequently, as the slab is reduced from
eight to nine inches thick to the final bar thickness of one to one and
one-half inches, bars tend to spread width-wise by a few inches at
their extremities, and by as much as an inch through the body.
6. Descaling
It is Descaled by the low pressure headers. After descaling by the
low-pressure headers, the bar is pinched by a pair of pneumatically-
actuated rolls to mechanically loosen any remaining scale, which, as
the processing temperatures cool off, becomes increasingly sticky
even as it returns ever more slowly to the surfaces of the still red-
hot steel.
7. Cropping
The head- and tail-ends of nearly every transfer bar are cropped by
a pair of large steel drums each with a shear blade extending along
its length.

8. 8. Finishing
Prior to the finish rolling operation, the head- and tail-ends of
the transfer bar will be sheared to square them up, helping to
ensure proper threading and tail-out. A final two-stage
descaling operation is performed to clean off the scale that has
grown on the bar during roughing.
Controlling Factors:-
I. Temperature Control
II. Gauge Control
III.Flatness & Crown
IV.Laminar Cooling
V. Coiling
VI.Coil Handling

9. Usages Of HR coils:-

10. Other Applications:-
General structures:-
Simple cross sections, such as rail tracks, storage tanks,
storage bins, tubes & pipes, cold-rolled steel,
Automotive parts:-
High-pressure gas cylinders, oil well pipes, pipelines ,
bearing plates for buildings and other structural
applications.

11. Application of HR coils in Various product
manufacturing:-
Tube making
Manufacture of Hamilton and other poles, flanging applications
Manufacture of pipes mostly for oil and gas sector
Cold reduction and for manufacture of galvanized sheets
General structural applications
Strapping, cycle chain
Manufacture of electrical equipment
Structural fabrication
Various applications in auto sector
Manufacture of corrosion resistant structural materials
For high tensile structural applications
Manufacture of propeller shaft
Manufacture of fork for two wheelers
Manufacture of wheel disc

12. Types of HR Coils:-
 Hot-rolled Coil
 Hot-rolled Sheets
 Checkered Plate

13. Major players :-
Dominated by 6-7 players:-
• Main : SAIL, TISCO, Jindal Steel
• Secondary : Essar Steel, Jindal Vijayanagar Steel Ltd
(JVSL), Jindal Iron and Steel Company (JISCO), Uttam
Steel
• The global market price of HR Coils is regarded as an
indicator of the market trend of all its downstream
products in the flat product segment.
• Its downstream products like CR Sheets / Coils, GP/GC
Sheets, Electrical Steel, Sheets, Tinplate, Pipes etc. play a
vital role in the industrial development of a country.

14. User segments
•Pipes & tubes and CR coils major users of HR coils
•CR coils used mainly for automobiles, consumer durables,
general engineering, construction as galvanized products
Some More User:-
•Railways
•Power
•Irrigation
•Coal
•Oil
•Product & Technology
•Furniture makers
•Consumer durables
•Agricultural
Implements

15. application

16. Contd…..