This is my practicum defense presentation as part of my BSME degree requirements.

1. Report Title:
A study on Manufacturing of Deformed
Bar G-60 400W at Elite Iron and Steel
Industries
Presenter:
Razin Sazzad Molla
ID: 13107010
Department of Mechanical Engineering
Supervisor:
Dr. A.K.M. Solayman Hoque
Faculty, Department of Mechanical Engineering
IUBAT- International University of Business Agriculture and Technology

2. Content
• Company Profile
• Objectives
• Manufacturing
• Engineering Materials
• Types of Steel Mills
• Steelmaking Process
• Semi-finished product
• Scrap
• Crystalline Structures
• Imperfections in Crystals
• Alloys and Phase Diagrams
• The Iron–Carbon Phase Diagram
• Conventional Iron and Steel Production
• Ironmaking
• Steelmaking
• The electric arc furnace
• Continuous Casting
• Classification of Steel
• Production at Elite Steel
• Quality Control
• Product Specification
• Problem Findings
• Conclusion
• Recommendation

3. Company Profile
Elite Iron & Steel Ind. Ltd. a unit of Elite Group of Industries was formed in 1987 a prominent
steel plant in Bangladesh. The company has installed Electric Induction Furnace in 1987 and
Re-Rolling Mills in 1996.
Today, Elite Steel is widely recognized as a foremost leader in the steel industry around
Bangladesh, extending its pioneering commitment from an expansive mill site located in the
heart of the Gazipur Industrial area, near National University.
Company at a glance:
Land: 80,000 square feet, Established: 1987, Authorized capital: None, Paid up capital:
None
Man power: Workers:60, Staff:10, Officer:5, Total:75
Performance: Company’s productions in the following fiscal years are as follows:
2013-14 15600 MT
2014-15 16200 MT
2015-16 16800 MT
2016-17 18000 MT

4. Objectives
The discussion of this report comprises iron and steel making process including ore chemistry, composition
and their reduction, manufacturing processes, metal forming and property enhancing processes, microscopic
behavior, bulk deformation processes including rolling operation. The objectives that the excerpt serve are as
follow:
• Gives the reader an overview of major manufacturing processes, their differences and interrelation.
• Provides discussion on engineering materials with special emphasis on ferrous metals and alloy.
• Making a clear, cohesive concept of alloy chemistry, grain formation, relation between mechanical
properties and other parameters like grain size and grain boundary.
• Presenting Iron Carbon Phase diagram and differentiating regions of steels and cast iron with discussion of
types of steels and microstructure.
• Discussing solidification process such as casting and procedures.
• Comparing modern Iron and steelmaking with operation of Elite.
• Identifying Steel types, composition and mechanical properties such as yield strength and tensile strength.
• Offering a brief discussion of hot rolling process

5. Manufacturing, Manufacturing Industry and Processes
The term manufacturing is used for this activity of making things. The word manufacture is
derived from two Latin words, manus (hand) and factus (make); the combination means made by
hand.
Two ways to define manufacturing in modern context: Technologically and Economically.
Technologically, manufacturing is the application of physical and chemical processes to alter the
geometry, properties, and/or appearance of a given starting material to make parts or products;
manufacturing also includes assembly of multiple parts to make products.
Characteristics of manufacturing processes:
• involves a combination of machinery, tools, power, and labor.
• carried out as a sequence of operations
• Each operation brings the material closer to the desired final state.
Economically, manufacturing is the transformation of materials into items of greater
value by means of one or more processing and/or assembly operations, as depicted in the
following figure.
The words manufacturing and production are often used interchangeably.

6. Fig 3.1: Defining manufacturing (a) as a technical process (b) as an economic process

7. Manufacturing Industry: Industry consists of enterprises and organizations that produce or
supply goods and services. Industries can be classified as primary, secondary, or tertiary
Primary industries cultivate and exploit natural resources, such as agriculture and mining.
Secondary industries take the outputs of the primary industries and convert them into consumer
and capital goods. Manufacturing is the principal activity in this category, but construction and
power utilities are also included.
Tertiary industries constitute the service sector of the economy.
Steel industry is a secondary industry whereas mining iron ore is a primary industry.
Manufacturing Processes: A manufacturing process is a designed procedure that results in
physical and/or chemical changes to a starting work material with the intention of increasing the
value of that material.
• carried out as a unit operation, which means that it is a single step in the sequence of steps
required to transform the starting material into a final product.
• Manufacturing operations can be divided into two basic types: (1) processing operations and
(2) assembly operations.

8. A processing operation transforms a work material from one state of completion to a
more advanced state that is closer to the final desired product. It adds value by changing
the geometry, properties, or appearance of the starting material.
An assembly operation joins two or more components to create a new entity, called an
assembly, subassembly, or some other term that refers to the joining process (e.g., a
welded assembly is called a weldment).
Steel industries generally deal with shaping operation (casting, metal forming, sheet metal
working and bulk deformation of metal) and property enhancing processes like heat
treatment (normalizing, annealing and water quenching to form martensite in case of TMT
bar)

9. Fig 3.3: Classification of manufacturing processes

10. Engineering Materials
Most engineering materials can be classified into one of three basic categories: (1) metals, (2)
ceramics, and (3) polymers. Their chemistries are different, their mechanical and physical
properties are different, and these differences affect the manufacturing processes that can be
used to produce products from them. In addition to the three basic categories, there are
composites: nonhomogeneous mixtures of the other three basic types rather than a unique
category.
Metals: Metals are the most important engineering materials. A metal is a category of
materials generally characterized by properties of ductility, malleability, luster, and high
electrical and thermal conductivity. The category includes both metallic elements and their
alloys. Metals have properties that satisfy a wide variety of design requirements.
Metals used in manufacturing are usually alloys, which are composed of two or more
elements, with at least one being a metallic element. Metals and alloys can be divided into two
basic groups: (1) ferrous and (2) nonferrous.

11. Fig 3.2: Classification of the four engineering materials

12. Ferrous Metals: Ferrous metals are based on iron; the group includes steel and cast iron. These
metals constitute the most important group commercially, more than three fourths of the metal
tonnage throughout the world.
• Pure iron has limited commercial use, but when alloyed with carbon, iron has more uses and
greater commercial value than any other metal.
• Alloys of iron and carbon form steel and cast iron
Steel can be defined as an iron–carbon alloy containing 0.02% to 2.11% carbon. It is the most
important category within the ferrous metal group. Its composition often includes other alloying
elements as well, such as manganese, chromium, nickel, and molybdenum, to enhance the
properties of the metal. Applications of steel include construction (bridges, I-beams and nails),
transportation (trucks, rails, and rolling stock for railroads), and consumer products (automobiles,
appliances)
Cast iron is an alloy of iron and carbon (2% to 4%) used in casting (primarily sand casting).
Silicon is also present in the alloy (in amounts from 0.5% to 3%), and other elements are often
added also, to obtain desirable properties in the cast part. Cast iron is available in several different
forms, of which gray cast iron is the most common; its applications include blocks and heads for
internal combustion engines.

13. Nonferrous Metals: Nonferrous metals include the other metallic elements and their alloys.
In almost all cases, the alloys are more important commercially than the pure metals. The
nonferrous metals include the pure metals and alloys of aluminum, copper, gold, magnesium,
nickel, silver, tin, titanium, zinc, and other metals.
Ceramic: Ceramic is defined as a compound containing metallic (or semi metallic) and
nonmetallic elements. Typical nonmetallic elements are oxygen, nitrogen, and carbon.
Polymer: A polymer is a compound formed of repeating structural units called “mers”,
whose atoms share electrons to form very large molecules. Polymers usually consist of
carbon plus one or more other elements, such as hydrogen, nitrogen, oxygen, and chlorine.
Composites: Composites do not really constitute a separate category of materials; they are
mixtures of the other three types. A composite is a material consisting of two or more phases
that are processed separately and then bonded together to achieve properties superior to those
of its constituents.

14. Types of Steel Mills
A steel mill or steelworks is an industrial plant for the manufacture of steel. It may be an
integrated steel works carrying out all steps of steelmaking from smelting iron ore to rolled
product, but may also be plants where steel semi-finished casting products (blooms, ingots,
slabs, billets) are made, from molten pig iron or from scrap.
In general there are two types of steel mills:
Integrated Steel mill and Mini mill
An integrated steel mill has all the functions for primary steel production:
• iron making (conversion of ore to liquid iron),
• steel making (conversion of pig iron to liquid steel),
• casting (solidification of the liquid steel),
• roughing rolling/billet rolling (reducing size of blocks)
• product rolling (finished shapes).
Integrated mill

15. The principal raw materials for an integrated mill are iron ore, limestone, and coal (or coke).
• charged in batches into a blast furnace
• iron compounds in the ore give up excess oxygen and become liquid iron
• At intervals of a few hours, the accumulated liquid iron is tapped from the blast furnace and
either cast into pig iron or directed to other vessels for further steel making operations.
• Historically the Bessemer process was a major advancement in the production of
economical steel, but it has now been entirely replaced by other processes such as the basic
oxygen furnace (BOF).
• Molten steel is cast into large blocks called blooms. During the casting process various
methods are used, such as addition of aluminum, so that impurities in the steel float to the
surface where they can be cut off the finished bloom.
• Integrated mills are large facilities that are typically only economical to build in 2,000,000-
ton (2 million ton) per year annual capacity and up. Final products made by an integrated
plant are usually large structural sections, heavy plate, strip, wire rod, railway rails, and
occasionally long products such as bars and pipe.

16. Fig : Integrated steel mill in the Netherlands. The two large towers are blast furnaces.

17. Mini mill
• A mini mill is traditionally a secondary steel producer
• Usually it obtains most of its iron from scrap steel, recycled from used automobiles and
equipment or byproducts of manufacturing.
• Direct reduced iron (DRI) is sometimes used with scrap, to help maintain desired
chemistry of the steel, though usually DRI is too expensive to use as the primary raw
steelmaking material.
• A typical mini-mill will have an electric arc furnace for scrap melting, a ladle furnace or
vacuum furnace for precision control of chemistry, a strip or billet continuous caster for
converting molten steel to solid form, a reheat furnace and a rolling mill.
Continuous casting, also called strand casting, is the process whereby molten metal is
solidified into a "semi-finished" billet, bloom, or slab for subsequent rolling in the finishing
mills.

18. In Bangladesh most mini mills have induction furnace and some have continuous caster. Elite
Steel has 2 induction furnaces and does not have continuous caster. It uses cast iron mold to
form ingots of around 100 kg each. The raw materials of these mini mills in Bangladesh are
Scrap, and Ferro alloys for chemical balancing.
Abul Khair Steel (AKS) which is the largest in Bangladesh (1.4 million MT annual
production) has the only electric arc furnace (EAF) and is an integrated steel mill.
Elite Steel has very low production of MS 60 grade deformed bar only. It has annual
production of around 20,000 MT. From manufacturing point of view it has medium quantity
production which follows batch production.

19. Steelmaking Process
Steelmaking is the process of producing steel from iron ore and scrap. In steelmaking
impurities such as nitrogen, silicon, phosphorus, sulfur and excess carbon are removed from
the raw iron and alloying elements such as manganese, nickel, chromium and vanadium are
added to produce different grades of steel. Limiting dissolved gases such
as nitrogen and oxygen and entrained impurities (termed "inclusions") in the steel is also
important to ensure the quality of the products cast from the liquid steel.
In the 1850s and 1860s, the Bessemer process and the Siemens-Martin process turned
steelmaking into a heavy industry. Today there are two major commercial processes for
making steel, namely basic oxygen steelmaking, which has liquid pig-iron from the blast
furnace and scrap steel as the main feed materials, and electric arc furnace (EAF) steelmaking,
which uses scrap steel or direct reduced iron (DRI) as the main feed materials.
Modern steelmaking processes can be divided into two categories: Primary and Secondary
steelmaking. Primary steelmaking involves converting liquid iron from a blast furnace and steel
scrap into steel via basic oxygen steelmaking, or melting scrap steel or direct reduced
iron (DRI) in an electric arc furnace. Secondary steelmaking involves refining of the crude
steel before casting and the various operations are normally carried out in ladles.

20. Producing steel products consists primarily of two steps: casting semi-finished
billet/slab/bloom/ingot first and subsequently reducing them to usable products like rolled
sheet/coil, deformed bar/rod, steel plate, structural steel, pipes and tubes or stainless steel.
Ingot: Ingot is commonly used name for the large sized castings produced in a foundry or
during iron making. In steelmaking, it is the first step among semi-finished casting products.
There are no specific standard dimensions for ingots. Ingots usually require a second
procedure of shaping, such as cold/hot working, cutting, or milling to produce a useful final
product. They are generally obtained in batch type process. At Elite Steel ingots of around
100 Kg each are produced in batch. One batch produces approximately 66 ingots.
Billet and Blooms are generally smaller in size. Elite Steel does not produce any of them.
Besides ingots of Elite Steel are far smaller than the conventional ingots.
Bloom: Blooms has rectangular /square cross section. The cross section area of bloom is
always greater than 36 𝑖𝑛2 (230𝑐𝑚2 ). Blooms are used as rolling material in the
manufacturing process of rails, seamless pipes, etc.
Semi-finished product

21. Slab: A slab can be considered as a special case of Bloom i.e. a Bloom with lesser thickness.
A slab is rolled from an ingot or a bloom and generally has a rectangular cross section of
about 250 mm by 40 mm.
Fig : Ingots at Elite Steel
Billet: Billet is also a casting product. In new era of industry, generally the billets are made
with the help of machine called as CCM (continuous casting machine). Billet has a square
cross section area, but cross section area of billet should be same through its length. The
cross section area of billet is always less than 36 𝑖𝑛2 . The Billets are used in the
manufacturing process of steel re-bars.

22. Scrap
Scrap consists of recyclable materials left over from product manufacturing and consumption,
such as parts of vehicles, building supplies, and surplus materials. Unlike waste, scrap has
monetary value, especially recovered metals, and non-metallic materials are also recovered for
recycling.
Ferrous metals are able to be recycled, with steel being one of the most recycled materials in
the world. Ferrous metals contain an appreciable percentage of iron and the addition of carbon
and other substances creates steel.
Recycling one metric ton (1,000 kilograms) of steel saves 1.1 metric tons of iron ore,
630 kilograms of coal, and 55 kilograms of limestone.
Types of scrap used in steelmaking:
Heavy melting steel, Old car bodies, Cast iron, Re-enforcing bars or mesh, Turnings,
Manganese steel, Rails
Elite Steel purchases only steel scrap (Plain Carbon) from both home and abroad. Scrap is also
produced inside the mill from defective products, removed/trimmed parts etc.

23. Crystalline Structures
Atoms and molecules are used as building blocks for the more macroscopic structure of
matter. When materials solidify from the molten state they tend to close ranks and pack
tightly, in many cases arranging themselves into a very orderly structure and in other cases
not quite so orderly. Two fundamentally different material structures can be distinguished:
(1) crystalline and (2) non crystalline.
Many materials form into crystals on solidification from the molten or liquid state. It is
characteristic of virtually all metals, as well as many ceramics and polymers. A crystalline
structure is one in which the atoms are located at regular and recurring positions in three
dimensions. The pattern may be replicated millions of times within a given crystal. The
structure can be viewed in the form of a unit cell, which is the basic geometric grouping of
atoms that is repeated.

24. Fig : BCC crystal structure: (a) unit cell (b) unit cell model showing closely packed atoms
(sometimes called the hard ball model) and (c) repeated pattern of the BCC structure.

25. Types of Crystal Structures
In metals, three lattice structures are common: (1) body-centered cubic (BCC), (2) face
centered cubic (FCC), and (3) hexagonal close-packed (HCP)
Some metals undergo a change of structure at different temperatures. Iron, for example, is
BCC at room temperature; it changes to FCC above 912 °C (1674 °F) and back to BCC at
temperatures above 1400 °C (2550 °F). When a metal (or other material) changes structure like
this, it is referred to as being allotropic.
The reason that metals form different crystal structures is to minimize the energy required to
fill space. At different temperatures, however, the same metal may form different structures,
because of a lower energy requirement. Iron forms a BCC structure (alpha iron) below 912°C
and above 1394°C (delta iron), but it forms an FCC structure (gamma iron, also called
austenite) between 912°C and 1394°C.

26. Fig : (a) body-centered cubic, (b) face-centered cubic, and (c) hexagonal close-
packed.

27. Imperfections in Crystals
Crystal structures are assumed to be perfect- the unit cell repeated in the material over and over
in all directions. However, there are various reasons why a crystal’s lattice structure may not be
perfect.
The imperfections often arise naturally because of the inability of the solidifying material to
continue the replication of the unit cell indefinitely without interruption. Grain boundaries in
metals are an example.
In other cases, the imperfections are introduced purposely during the manufacturing process;
for example, the addition of an alloying ingredient in a metal to increase its strength.
The various imperfections in crystalline solids are also called defects. Either term,
imperfection or defect, refers to deviations in the regular pattern of the crystalline lattice
structure. They can be catalogued as (1) point defects, (2) line defects, and (3) surface defects.
Point defects are imperfections in the crystal structure involving either a single atom or a few
atoms.
Point Defects

28. Fig : Point defects: (a) vacancy, (b) ion-pair vacancy, (c) interstitialcy, and (d) displaced ion.

29. Line Defect
A line defect is a connected group of point defects that forms a line in the lattice structure.
The most important line defect is the dislocation, which can take two forms: (a) edge
dislocation and (b) screw dislocation. Both types of dislocations can arise in the crystal
structure during solidification (e.g., casting), or they can be initiated during a deformation
process (e.g., metal forming) performed on the solid material. Dislocations are useful in
explaining certain aspects of mechanical behavior in metals.
Fig : Line defects: (a) edge
dislocation and (b) screw
dislocation.

30. Surface defects are imperfections that extend in two directions to form a boundary. The most
obvious example is the external surface of a crystalline object that defines its shape. The
surface is an interruption in the lattice structure. Surface boundaries can also lie inside the
material. Grain boundaries are the best example of these internal surface interruptions.
Deformation occurs in a crystal lattice, and the process is aided by the presence of
dislocations.
Surface defect

31. Deformation in Metallic Crystals
When a crystal is subjected to a gradually increasing mechanical stress, its initial response is to
deform elastically. If the force is removed, the lattice structure (and therefore the crystal)
returns to its original shape. If the stress reaches a high value relative to the electrostatic forces
holding the atoms in their lattice positions, a permanent shape change occurs, called plastic
deformation. What has happened is that the atoms in the lattice have permanently moved from
their previous locations, and a new equilibrium lattice has been formed. Two ways of plastic
deformation:
• lattice deformation called slip
• twinning
Slip involves the relative movement
of atoms on opposite sides of a
plane in the lattice, called the slip
plane. Dislocations play an
important role in facilitating slip in
metals.
Fig: Deformation of a crystal structure: (a) original lattice;
(b)elastic deformation, with no permanent change in
positions of atoms; and (c) plastic deformation, in which
atoms in the lattice are forced to move to new “homes.”

32. A given block of metal may contain millions of individual crystals, called grains. Each grain has its own unique
lattice orientation; but collectively, the grains are randomly oriented within the block. Such a structure is referred
to as polycrystalline. It is easy to understand how such a structure is the natural state of the material. When the
block is cooled from the molten state and begins to solidify, nucleation of individual crystals occurs at random
positions and orientations throughout the liquid. As these crystals grow they finally interfere with each other,
forming at their interface a surface defect—a grain boundary.
Grain size is inversely related to cooling rate: Faster cooling promotes smaller grain size, whereas slower cooling
has the opposite effect. Grain size is important in metals because it affects mechanical properties. Smaller grain
size is generally preferable from a design view point because it means higher strength and hardness. It is also
desirable in certain manufacturing operations (e.g. Metal forming), because it means higher ductility during
deformation and a better surface on the finished product.
Another factor influencing mechanical properties is the presence of grain boundaries in the metal. They represent
imperfections in the crystalline structure that interrupt the continued movement of dislocations. This helps to
explain why smaller grain size—therefore more grains and more grain boundaries—increases the strength of the
metal. By interfering with dislocation movement, grain boundaries also contribute to the characteristic property
of a metal to become stronger as it is deformed. The property is called strain hardening.
Grain and Grain Boundary

33. Fig: Grain and Grain Boundary

34. Alloys and Phase Diagrams
Although some metals are important as pure elements (e.g., gold, silver, copper), most engineering applications
require the improved properties obtained by alloying. Through alloying, it is possible to enhance strength,
hardness, and other properties compared with pure metals
An alloy is a metal composed of two or more elements, at least one of which is metallic. The two main
categories of alloys are (1) solid solutions and (2) intermediate phases.
Solid Solutions:
A solid solution is an alloy in which one element is dissolved in another to form a single-phase structure. The
term phase describes any homogeneous mass of material, such as a metal in which the grains all have the same
crystal lattice structure. In a solid solution, the solvent or base element is metallic, and the dissolved element can
be either metallic or nonmetallic. Solid solutions come in two forms:
• substitutional solid solution- in which atoms of the solvent element are replaced in its unit cell by the dissolved
element. Brass is an example, in which zinc is dissolved in copper.
• interstitial solid solution- in which atoms of the dissolving element fit into the vacant spaces between base
metal atoms in the lattice structure.
The most important example of this second type is carbon dissolved in iron to form steel. In both forms of solid
solution, the alloy structure is generally stronger and harder than either of the component elements.

35. Intermediate Phases
There are usually limits to the solubility of one element in another. When the amount of the dissolving
element in the alloy exceeds the solid solubility limit of the base metal, a second phase forms in the alloy.
The term intermediate phase is used to describe it because its chemical composition is intermediate between
the two pure elements. Its crystalline structure is also different from those of the pure metals.
(1) metallic compounds consisting of a metal and nonmetal such as Fe3C known as Iron Carbide or
Cementite; and
(2) intermetallic compounds- two metals that form a compound, such as Mg2Pb.
The composition of the alloy is often such that the intermediate phase is mixed with the primary solid solution
to form a two-phase structure, one phase dispersed throughout the second. These two-phase alloys are important
because they can be formulated and heat treated for significantly higher strength than solid solutions.

36. Fig: two phase system

37. Phase Diagrams:
A phase diagram is a graphical means of representing the phases of a metal alloy system as a function of
composition and temperature. This discussion of the diagram will be limited to alloy systems consisting of
two elements at atmospheric pressures. This type of diagram is called a binary phase diagram.
Table: Iron properties.

38. The Iron–Carbon Phase Diagram
Fig : Phase diagram of iron-carbon system, up to about 6% carbon.

39. Steel microstructure
Microstructure is the very small scale structure of a material, defined as the structure of a prepared surface of
material as revealed by a microscope above 25× magnification. The microstructure of a material (such as
metals, polymers, ceramics or composites) can strongly influence physical properties such as strength,
toughness, ductility, hardness, corrosion resistance, high/low temperature behavior or wear resistance.
Pearlite: Pearlite is a two-phased, lamellar (or layered) structure composed of alternating layers of ferrite
(88 wt. %) and cementite (12 wt. %) that occurs in some steels and cast irons.
Martensite: Martensite is formed in carbon steels by the rapid cooling (quenching) of the austenite form of
iron at such a high rate that carbon atoms do not have time to diffuse out of the crystal structure in large
enough quantities to form cementite (Fe3C). Austenite is γ-Fe, (gamma-phase iron), a solid solution of iron
and alloying elements. The highest hardness of a pearlitic steel is 400 Brinell whereas martensite can achieve
700 Brinell.
Austenite: Austenite, also known as gamma-phase iron (γ-Fe), is a metallic, non-magnetic allotrope of iron or
a solid solution of iron, with an alloying element. In plain-carbon steel, austenite exists above the critical
eutectoid temperature of 1000 K (727°C)
Bainite: Bainite is a plate-like microstructure that forms in steels at temperatures of 250–550 °C (depending on
alloy content).

40. Conventional Iron and Steel Production
Iron and steel production begins with the iron ores and other raw materials required. Ironmaking is discussed, in
which iron is reduced from the ores, and steelmaking, in which the iron is refined to obtain the desired purity and
composition (alloying).
Iron Ores and Other Raw Materials
The principal ore used in the production of iron and steel is hematite (Fe2O3). Other iron ores include magnetite
(Fe3O4), siderite (FeCO3), and limonite (Fe2O3-xH2O, in which x is typically around 1.5). Iron ores contain from
50% to around 70% iron, depending on grade (hematite is almost 70% iron). In addition, scrap iron and steel are
widely used today as raw materials in iron- and steelmaking.
Other raw materials needed to reduce iron from the ores are coke and limestone. Coke is a high carbon fuel
produced by heating bituminous coal in a limited oxygen atmosphere for several hours, followed by water spraying
in special quenching towers. Coke serves two functions in the reduction process: (1) it is a fuel that supplies heat
for the chemical reactions; and (2) it produces carbon monoxide (CO) to reduce the iron ore. Limestone is a rock
containing high proportions of calcium carbonate (CaCO3). The limestone is used in the process as a flux to react
with and remove impurities in the molten iron as slag.

41. Ironmaking
To produce iron, a charge of ore, coke, and limestone are dropped into the top of a blast furnace. A blast furnace
is a refractory-lined chamber with a diameter of about 9 to 11 m (30–35 feet) at its widest and a height of 40 m
(125 feet), in which hot gases are forced into the lower part of the chamber at high rates to accomplish
combustion and reduction of the iron.
The reactions are as follows:
Fe2O3 + CO = 2FeO + CO2
Carbon dioxide reacts with coke to form more carbon monoxide:
CO2 + C (coke) = 2CO
Which then accomplishes the final reduction of FeO to iron:
FeO + CO = Fe + CO2
The molten iron drips downward, collecting at the base of the blast furnace. This is periodically tapped into hot
iron ladle cars for transfer to subsequent steelmaking operations.
The role played by limestone can be summarized as follows. First the limestone is reduced to lime (CaO) by
heating, as follows
CaCO3 = CaO + CO2

42. The lime combines with impurities such
as silica (SiO2), sulfur (S), and alumina
(Al2O3) in reactions that produce a molten
slag that floats on top of the iron. It is
instructive to note that approximately 7
tons of raw materials are required to
produce 1 ton of iron. The ingredients are
proportioned about as follows: 2.0 tons of
iron ore, 1.0 ton of coke, 0.5 ton of
limestone, and (here’s the amazing
statistic) 3.5 tons of gases. A significant
proportion of the byproducts are recycled.
Fig : Cross section of ironmaking blast furnace.

43. Steelmaking
Since the mid-1800s, a number of processes have been developed for refining pig iron into steel. Today, the two
most important processes are the basic oxygen furnace (BOF) and the electric arc furnace. Both are used to produce
carbon and alloy steels.
• The BOF is an adaptation of the Bessemer converter
• Whereas the Bessemer process used air blown up through the molten pig iron to burn off impurities, the basic
oxygen process uses pure oxygen.
• Integrated steel mills transfer the molten pig iron from the blast furnace to the BOF in railway cars called hot-
iron ladle cars. In modern practice, steel scrap is added to the pig iron, accounting for about 30% of a typical
BOF charge.
Pure O2 is blown at high velocity through the lance, causing combustion and heating at the surface of the molten
pool. Carbon dissolved in the iron and other impurities such as silicon, manganese, and phosphorus are oxidized.
The reactions are:
2C + O2 = 2CO (CO2 is also produced)
Si + O2 = SiO2
2Mn + O2 = 2MnO
4P +5O2 = 2P2O5
A 200-ton heat of steel can be processed in about twenty minutes although the entire cycle time (tap-to-tap time)
takes about 45 minutes.

44. Fig: Basic Oxygen furnace showing BOF vessel. Fig: (1) charging scrap (2) pig iron (3) blowing (4)
tapping molten steel (5) pouring off the slag

45. • accounts for about 30% of U.S. steel production.
• Although pig iron was originally used as the charge in this type of furnace, scrap iron and scrap steel are the
primary raw materials today.
• Electric arc furnaces are available in several designs; the direct arc type shown in figure is currently the most
economical type.
• These furnaces have removable roofs for charging from above; tapping is accomplished by tilting the entire
furnace.
• Scrap iron and steel selected for their compositions, together with alloying ingredients and limestone (flux), are
charged into the furnace and heated by an electric arc that flows between large electrodes and the charge metal.
• Complete melting requires about 2 hours; tap-to-tap time is 4 hours.
• Capacities of electric furnaces commonly range between 25 and 100 tons per heat.
• Electric arc furnaces are noted for better-quality steel but higher cost per ton, compared with the BOF.
• The electric arc furnace is generally associated with production of alloy steels, tool steels, and stainless steels.
The electric arc furnace

46. Fig : Electric arc furnace

47. Continuous Casting
The continuous casting process, also called
strand casting, is illustrated in figure.
Molten steel is poured from a ladle into a
temporary container called a tundish,
which dispenses the metal to one or more
continuous casting molds. The steel begins
to solidify at the outer regions as it travels
down through the water-cooled mold.
Water sprays accelerate the cooling
process. While still hot and plastic, the
metal is bent from vertical to horizontal
orientation. It is then cut into sections or
fed continuously into a rolling mill in
which it is formed into plate or sheet stock
or other cross sections.
Fig : Continuous casting operation

48. Classification of Steel
As defined earlier, Steel is an alloy of iron that contains carbon ranging by weight between 0.02% and 2.11%
(most steels range between 0.05% and 1.1% C). It often includes other alloying ingredients, such as manganese,
chromium, nickel, and/or molybdenum, but it is the carbon content that turns iron into steel. Hundreds of
compositions of steel are available commercially. For purposes of organization here, the vast majority of
commercially important steels can be grouped into the following categories:
• (1) plain carbon steels,
• (2) low alloy steels,
• (3) stainless steels,
• (4) tool steels, and
• (5) specialty steels.
Plain Carbon Steels: These steels contain carbon as the principal alloying element, with only small amounts of
other elements (about 0.4% manganese plus lesser amounts of silicon, phosphorus, and sulfur). The strength of
plain carbon steels increases with carbon content. As seen in the phase diagram for iron and carbon steel at room
temperature is a mixture of ferrite (alpha) and cementite (Fe3C). The cementite particles distributed throughout
the ferrite act as obstacles to the movement of dislocations during slip; more carbon leads to more barriers, and
more barriers mean stronger and harder steel.

49. Table: AISI-SAE designations of steels

50. According to a designation scheme developed by the American Iron and Steel Institute (AISI) and the
Society of Automotive Engineers (SAE), plain carbon steels are specified by a four-digit number system:
10XX, in which 10 indicates that the steel is plain carbon, and XX indicates the percent of carbon in
hundredths of percentage points. For example, 1020 steel contains 0.20% C.
1. Low carbon steels contain less than 0.20% C and are by far the most widely used steels.
2. Medium carbon steels range in carbon between 0.20% and 0.50% and are specified for applications
requiring higher strength than the low-C steels. Applications include machinery components and engine
parts such as crankshafts and connecting rods.
3. High carbon steels contain carbon in amounts greater than 0.50%. They are specified for still higher
strength applications and where stiffness and hardness are needed. Springs, cutting tools and blades, and
wear-resistant parts are examples. Increasing carbon content strengthens and hardens the steel, but its
ductility is reduced. Also, high carbon steels can be heat treated to form martensite, making the steel very
hard and strong.

51. Low Alloy Steels
Low alloy steels are iron–carbon alloys that contain additional alloying elements in amounts totaling
less than about 5% by weight. Owing to these additions, low alloy steels have mechanical properties
that are superior to those of the plain carbon steels for given applications. Superior properties usually
mean higher strength, hardness, hot hardness, wear resistance, toughness, and more desirable
combinations of these properties. Heat treatment is often required to achieve these improved properties.
Common alloying elements added to steel are chromium, manganese, molybdenum, nickel, and
vanadium, sometimes individually but usually in combinations. These elements typically form solid
solutions with iron and metallic compounds with carbon (carbides), assuming sufficient carbon is
present to support a reaction. The effects of the principal alloying ingredients can be summarized as
follows:

52. Stainless Steels
Stainless steels are a group of highly alloyed steels designed to provide high corrosion resistance. The principal
alloying element in stainless steel is chromium, usually above 15%. The chromium in the alloy forms a thin,
impervious oxide film in an oxidizing atmosphere which protects the surface from corrosion. Nickel is another
alloying ingredient used in certain stainless steels to increase corrosion protection. Carbon is used to strengthen
and harden the metal, however, increasing the carbon content has the effect of reducing corrosion protection
because chromium carbide forms to reduce the amount of free Cr available in the alloy.
Austenitic stainless have a typical composition of around 18% Cr and 8%Ni and are the most corrosion
resistant of the three groups.
Ferritic stainless have around 15% to 20% chromium, low carbon, and no nickel. This provides a ferrite
phase at room temperature.
Martensitic stainless have a higher carbon content than ferritic stainlesses, thus permitting them to be
strengthened by heat treatment. They have as much as 18% Cr but no Ni.
Precipitation hardening stainless, which have a typical composition of 17% Cr and 7%Ni, with additional
small amounts of alloying elements such as aluminum, copper, titanium, and molybdenum.

53. Casting and molding processes dominate this category of shaping operations.
Sand Casting:
Sand casting is the most widely used casting process, accounting for a significant majority of the total tonnage
cast. Nearly all casting alloys can be sand cast;
Sand casting, also known as sand-mold casting, consists of pouring molten metal into a sand mold, allowing the
metal to solidify, and then breaking up the mold to remove the casting.
Metal Forming
Metal forming includes a large group of manufacturing processes in which plastic deformation is used to
change the shape of metal workpieces.
Metal forming processes can be classified into two basic categories: bulk deformation processes and sheet
metalworking processes.
Bulk Deformation Processes: Bulk deformation processes are generally characterized by significant
deformations and massive shape changes, and the surface area-to-volume of the work is relatively small.
Rolling: This is a compressive deformation process in which the thickness of a slab or plate is reduced by two
opposing cylindrical tools called rolls. The rolls rotate so as to draw the work into the gap between them and
squeeze it.
Solidification Process

54. Production at Elite Steel
• Elite Still is considered a mini mill.
• Unlike the integrated mill it does not convert iron ore to pig iron.
• The finished product of Elite Steel Ind. are the 60 Grade 400 W deformed bar and TMT 500 W deformed bar /
rebar where the W stands for “weldable”
• The nominal diameters of the products are 10 mm, 12mm, 16mm, 20mm, 22mm, 25mm, 28mm, and 32 mm.
• Elite Steel produces rebar according to British (BS 4461:1978, BS4449:1988), German (DIN 488: DIN 1045),
India (IS 1786: 1985, IS 456), French (BA 1968), Russian (GOST 25 G 2 C), Japanese (JIS G3112 (1961)) &
Bangladeshi (BDS 1313:1990) standards
• The 60 grade MS bar is said to have yield strength (YS) of around 450 ~ 480 MPa (65000 psi) and ultimate tensile
strength of around 710 MPa (~100000 psi).
• Thermo-Mechanically treated (TMT) bars which are designated as TMT 500 W are said to have minimum YS of
500 MPa (72000 psi). Besides this there is also G-40 300 W rebar which is not manufactured at Elite Steel. G 40
has YS of around 300 MPa.
• The monthly production of the mill is around 1700 metric ton.
• The entire mill is divided into two section: the furnace section and the rolling section namely. The furnace section
make use of the steel scrap and melt them in its two induction furnaces. The rolling section consists of 4 repeating
stands starting from roughing mill to finishing mill and a PLC controlled continuous mill for 10, 12 and 16 mm
rods.

55. The approximate area of the factory is
80,000 square feet. Due to shortage of
available space the mill has been
congested. The factory map is shown
below:
Fig: Factory Map
Factory Layout

56. The furnace section (Scrap melting section): Transforms steel scrap into ingots through CI mold casting. It
consists of 2 induction furnaces of 6.5 ton each. The furnaces are used alternately. The power supply unit,
frequency converter, hydraulic system for tilting, cooling pumps all are located downstairs while the entrance of
furnace is upstairs.
Fig: Ingot casting operation with induction furnace behind

57. Scrap yard: It is the place where purchased steel scraps are kept. Steel scraps are unloaded from the trucks via
the magnetic crane. Only steels are kept here by filtering process. Since the mill has very little refining
capability chemical composition of scrap must be in close tolerance. Carbon content of mild steel has to be
around 0.40% maximum. Controls chemical composition by altering cast iron content or Ferro alloy content.
Fig : Scraps are stored (left) and truck awaiting unloading (right)

58. Physical testing lab: Equipped with Universal Testing machine (UTM) for tensile test which is fully automatic.
Has also bend test machine. It supplies test reports to its clients as demanded.
Fig: Universal Testing Machine (left) and test sample (right)

59. Chemical testing lab: Chemical control is the most important part of casting and rolling. Chemical
composition has to be tested multiple times before casting of ingots to make sure they are within limits. Ingots
are later tested to check for specific diameter requirement.
Refractory section: They are vital part of ingot casting since the plate and the runner requires refractory bricks
to be placed in the plate and inside the runner for casting. They have to be replaced with new sets of bricks every
time a new heat is casted! A “Heat” is colloquially known as one batch of ingot which at Elite Steel usually 66
ingots each is being around 100 Kg. (6.5 Ton)
Fig : Refractory bricks made from sand (silica) and sodium silicate (inorganic binder)

60. Rolling section: Ingots are loaded periodically via the hydraulic pusher into the gas/coal fired reheat furnace and
brought to around 1200 C before ejecting them onto the drawing table which passes it to the first mill stand
which is known as roughing stand. By repeating reversing method the 4.5/3.5 inch ingot is lengthened and
thickness is reduced by passing it through 2 intermediate and the final stand. By the help of pinch rolls and the
flying shear bars are cut to the required sizes and brought to the cooling bed.
Fig : Mill stands (top) and rollers (bottom)

61. Mechanical workshop: Is equipped with 5 lathes, 2 shaper, drills, boring and milling machines. Has multiple
welding power supply, Oxy fuel cutter, Arc welding fixture, spare rollers, spindles, fibers and all other relevant
tools. The roller rib marks are manually cut here.
Fig : Roller rib cutting (left), shaper (right) and spare rollers (bottom)

62. Continuous mill: There is a continuous mill which is used for the production of 10, 12 and 16 mm rod. It
consists of 4 stands which all are run by DC motor. Unlike the roughing mill here the RPM of each stand can
be fixed via the PLC panel. Thickness is reduced by 1.5mm in every stand.
Fig : Continuous mill.

63. Process Flow chart: Production begins from
melting scrap for subsequent rolling operation.
The sequence of overall process is as follows:
Fig: Sequence of processes

64. Operation process: The entire operations of making deformed bad is mainly done in 2 broad sections
namely the furnace section and the rolling section. Processes of these sections are discusses in detail below:
Furnace section (Steel melting section):
• At Elite Steel scarps are purchased from both home and abroad and discharged daily.
• The scrap is the only raw material that has ferrous content. Due to very little refining ability of the induction
furnace scrap has to be pure and free of non-ferrous metals or ceramics.
• Primary checking and filtering is done while discharging .A typical truck contains usually around 12 tons of
scrap.
• The workers at Elite steel filters unwanted materials out. Only medium carbon steel are kept.
• Cast iron material is separated to melt in a controlled amount to balance carbon content if the carbon
content is less.
• Aluminum ring is also separated to use in every heat.
• Ferro alloys of different types are used to mix with molten steel to balance chemical compositions.

65. Heat:
• Every batch of ingot is colloquially called “heat” at the factory, the first batch of the first day of a month being
numbered 1.
• As different size of rods require different ingots it’s a way of identifying ingots.
• In a month approximately 300 heat is produced, each heat having about 66 ingots. For example “H-105” means
heat number 105 which indicates that 104 heat was cast before that in that particular month.
• Chemical testing of a sample cut from that specific heat will reveal its chemical including carbon composition
and they will know which diameter rod that ingot is for. At Elite approximately 10 heat is produced in 24 hours.
Fig : H-113 (heat number 113) being transferred to reheat
furnace

66. Production of a heat begins with some simultaneous processes:
• The two overhead cranes keeps operating which are operated by humans. Magnet can be attached with them and
can be replaced with hooks for carrying slag box, plate, molds or the tundish.
• The first step is to turn on the power supply system of one of the two induction furnace systems. At Elite there are
two furnaces but only one at a time can be run due to limited power.
• The furnace men keeps charging scraps into the furnace crucible until they completely melt and they keep adding
charges until it fills. Periodically they discard slag from the top which always floats on top. The slag box is there to
store and discard slags.
• In the meantime plateman and other workers prepare plate, mold and column and set all these up below the furnace
spout. It takes around two and a half hours to cast one batch.
• Two sets of molds are alternately used each mold weighing about 550 kg.
• This is permanent mold casting and each mold casts 2 ingots each of which is around 100 kg.
• Before pouring the molten metal through the tundish sample is taken once or twice from the crucible and tested
instantly at the lab for chemical composition. If the carbon is less than required they add cast iron into the charge
and if carbon is more than required they add low carbon steel scrap to equalize the carbon content.
• Ferro alloys (Ferro manganese, Silicon Manganese and Ferro Silicon) are weighed and added at the final stage.
• Temperature is kept at around 1560 C for the final molten metal. The furnaces are induction furnace which works
by the principle of electro magmatic induction. A static frequency converter converts the AC mains frequency of
50Hz to around 700 Hz.

67. Induction furnace: A furnace is a device used for high-temperature heating. An Induction Furnace uses
induction to heat a metal to its melting point which is based on the theory of Electromagnetic Induction.
Induction furnaces are ideal for melting and alloying a wide variety of metals with minimum melt losses,
however, little refining of the metal is possible. The induction furnace consists basically of a crucible, inductor
coil, and shell, cooling system and tilting mechanism. Depending on their frequency (50 Hz - 250 kHz) these can
be divided to three types:
1. High Frequency
2. Medium Frequency
3. Low Frequency
Induction Heating:
Induction heating is a form of non-contact heating for conductive materials.
The principle of induction heating is mainly based on two well-known physical phenomena:
1. Electromagnetic induction
2. The Joule effect

68. Electromagnetic Induction
The energy transfer to the object to be heated occurs by means of electromagnetic induction. Any electrically
conductive material placed in a variable magnetic field is the site of induced electric currents, called eddy
currents, which will eventually lead to joule heating.
Fig : Electromagnetic induction and eddy current induced.

69. Joule Heating
Joule heating, also known as ohmic heating and resistive heating, is the process by which the passage of an
electric current through a conductor releases heat. The heat produced is proportional to the square of the current
multiplied by the electrical resistance of the wire.
𝑄 ∝ 𝐼2 𝑅
Fig: Electromagnetic induction leads to Joule heating

70. Features of Induction Furnace:
An electric induction furnace requires an electric coil to produce the charge. This heating coil is eventually
replaced.
 The crucible in which the metal is placed is made of stronger materials that can resist the required heat, and
the electric coil itself cooled by a water system so that it does not overheat or melt.
 The advantage of the induction furnace is a clean, energy-efficient and well controllable melting process
compared to most other means of metal melting.
 Induction furnace capacities range from less than one kilogram to one hundred tons capacity, and are used to
melt iron and steel, copper, aluminum, and precious metals.
 The one major drawback to induction furnace usage in a foundry is the lack of refining capacity; charge
materials must be clean of oxidation products and of a known composition, and some alloying elements may
be lost due to oxidation (and must be re-added to the melt).
Depending on their construction they can be divided into two types: coreless and channel.

71. Fig: Medium-frequency coreless induction furnace

72. Specification of furnace at Elite Steel:
Coreless type vertical, medium frequency copper coil, crucible electric induction furnace.
Manufacturer: Megatherm Electronics Pvt. Ltd (India)
Power supply: Solid state power supplies
Capacity: 6.5 Ton each (x2)
Crucible volume: around 3m3
Power: 800 V, 2500 A, 2000,000 VA, (~3MW Maximum)
AC input type: 3 phase, 50Hz.
Output Frequency: 750 Hz.
Crucible: Cylindrical, ceramic built.
Auxiliary system: Tilting mechanism, Water Cooling system, Copper coil and power coil, patching, fume
extraction system.

73. Fig: Furnace mouth (left) and furnace being tilted for pouring (right).

74. Furnace power supply and control
The heart of Induction Heating Application is the solid state power supply. The solid state static frequency
converter converts the AC main frequency to around 500Hz. There is a step down transformer next to the
furnace house which converts 11KV to 800V. The crucible is formed from refractory material, which the
furnace coils is lined with. This crucible holds the charge material and subsequently the melt.
Fig: Power supply panel(left) capacitors (middle) and control panel (right).

75. Furnace operation and maintenance:
Since each furnace cannot be used for more than 10/13 heat furnaces have to be altered every day. There is a
refractory lining around the crucible which wears away with every heat. After every 10/12 heat the refractory
lining is rebuilt which is called patching. Limestone or calcium carbonate is used for patching. A cylindrical
forma is used as a guide for patching.
Auxiliary systems: Hydraulic system, Cooling system, Fume Extraction System
Fig : Water pump (left), water pipes in green attached with furnace (middle), patching of furnace (right)

76. Fig : Furnace tilted at maximum position by operating lever (left) and cast ingot (right)

77. Slag box: It is where slag is poured periodically during melting. There are two slag box used to transport and
transfer slag. The slag always floats on top and workers keep filtering it periodically. Once or twice the furnace
is tilted and slags are discarded on a large scale.
Fig: Slag box (left) and slag being poured (right)

78. Tundish and Center column:
In metal casting, a tundish is a broad, open container with one or more holes in the bottom. It is used to feed
molten metal into an ingot mold so as to avoid splashing and give a smoother flow. At Elite steel there are two
tundishes and the hole sits on top of the column which smoothly spreads the molten metal to all the molds.
Center column is the tall cylindrical pipe through which molten metal flows from the tundish. The column is
about 2.5 ton. The column encircles refractory lining which are circular and fills the entire hollow section. On
top of the column there sits a cap.
Fig : Refractory brick setup (left), center column (middle) and tundish (right)

79. Bottom Plate making: Plate is called the heavy cast iron platform on which molds are set. It weighs about 5
Ton. Plate is the base which holds the entire setup including all the molds and runner and molten metal. A
plate can fix around 33 molds which in turns produce 66 ingots.
Fig : Plate making and refractory bricks

80. Cast Iron (CI) mold
• molds made of cast iron which are the most essential part among all other things.
• hold and shape ingots. (550 Kg each and have 2 hollows/mold cavities to cast ingot).
• Elite Iron has 2 sets of molds imported from India. One set consists of 33 ingots which can cast 66 ingots.
This is permanent mold casting but the mold eventually breaks down and need to be replaces with new set.
Each mold casts 2 ingots.
• Molds are hooked on top to be lifted by the cranes. Molten metal from spout flows towards tundish and
through center column finally reaches every mold and rises upward and fill the shape of the rectangular
molds.
• Molten metal falls freely due to gravity and rises upward against gravity. The ingots are open on top so air
can freely pass to make room for molten steel. At 1650 °C steel is in fluid state and acts a fluid. The
density and viscosity both reduces. After solidification the molds are lifted up by the crane and taken
away for cooling.

82. Fig: Mold setup before casting and after casting

83. Furnace Oil: Furnace oil is a dark viscous residual product used as a fuel in different types of combustion
equipment. At Elite Steel furnace oil is used as a lubricant so mold can be lifted up after solidification. It also
works as a fuel.
Fig : Furnace Oil being applied to rails and molds interior

84. Ingots and chemical sampling
Batches of ingots are cast and marked with heat number. As per requirement ingots are produced and chemical
Spectrometer is used to see chemical compositions. Small cylindrical portion is cut from ingot to test. Different
ingots are used for rolling of different rods. For example the ingot for 10 mm diameter is not same as the ingot
for 32 mm. The elements that can be tested by the single spark are carbon, silicon, manganese, phosphorous,
sulfur, chromium, molybdenum, nickel, aluminum, cobalt, copper, niobium, titanium, vanadium, tungsten, lead,
tin, arsenic, zirconium, calcium, antimony, boron, nitrogen and iron.
Fig : Chemical spectrometer and sample on top

85. At Elite all are MS or Medium Carbon Steel/ Mild steel (approximately 0.29% to 0.54% carbon content with
0.60 to 1.00% manganese content (e.g. AISI 1040 steel)). At Elite Carbon content for ingots of smaller
diameter is kept around 0.33% and ingots of larger diameter are around 0.40% maximum. Other elements
include Manganese (1.00% max), Silicon, Phosphorus, Sulphur and Copper. Plain Carbon steel is
nonresulphurized. Elite steel follows AISI-SAE designation and composition system.
Fig: Chemical composition

86. The three types of Ferro alloys are used at Elite Steel for alloying purpose. They are also used to stop steel from
oxidizing again. Aluminum has to be added in every heat to prevent steel from re-oxidizing. Ferro alloys are:
 Ferro Manganese (FeMn)
 Ferro Silicon (FeSi)
 Silicon Manganese (SiMn)
Ferro Alloys

87. Rolling Section
• beginning of the production from ingot to deformed bar.
• Through sequential operation starting from the reheat furnace the 100 Kg ingot is hot rolled above its
recrystallization temperature and rod of different diameter is produced by its rolling stands.
• The beginning of rolling operations begins from reheating the ingots at around 1200 C. They are then
ejected out of the furnace through the ejector and drawn to the dressing table and Y table. The
thickness of the ingot is reduced by repeating and reversing the ingot through the roughing mill. Elite
steel has 3 high rolls. There are 4 stands in total. The first one is roughing stand, two intermediate
stands and one finishing stand. There are also 4 DC continuous stands for the production of 10, 12 and
16mm rod.

88. Reheat furnace: It is a gas/coal fired long rectangular furnace whose one end receives ingot at ambient
temperature and gradually as the ingots comes near final end it stays inside long enough to come to an uniform
temperature throughout. The reheat furnace temperature is kept around 1100°C. The ejector is a long bar which
by means of worm gear drive works and pushes ingots out of the furnace gate to the dressing table.
Fig : Ejector (left), coal feeder (right)

89. Roughing motor: It is a 3 phase induction slip ring motor of 1000HP. It drives all 4 stands via gear box. The
gear box is reduction gear with input rpm 950 and output rpm being 55. Due to heavy load it’s a slip ring motor
and stator winding is attached with rheostat. A heavy flywheel is connected with the motor shaft which weighs
around 20 ton. The motor itself weighs some 15 Ton.
Fig : Roughing motor, coupling and flywheel.

90. Dressing Table: It is the table with sets of rollers which guides the ingot from furnace mouth to the first roughing
stand. The rollers are all driven by chain drive and motors which can be reversed to bring the ingot at desired
place and change roughing passes.
Fig : Dressing table (left), ingot passing through table (right)

91. Rollers and guide: Rollers are rotating cylinders of 400 mm diameter which has fixed space in between two
of them. They squeeze and by dint of compressive force reduce the thickness of the work progressively.
There are three rollers in first three stands which is called 3 high mill and the finishing mill has 2 rollers.
There is a continuous mill with 4 stands which all have 2 rollers in each stand. Guide and guide box are the
rectangular part through which hot bar passes and repeats. They have different shapes and directions.
Fig : Ingots approaching rollers (left) rollers and guide (right)

92. Roughing Mill: The 4 roughing stands are collectively called roughing mill. They are horizontal and aligned
straight. They all have the same rotational speed. The torque is transferred via spindles.
Fig : Roughing mill (left) and first roughing stand with guide shown (right)

93. Repeater: Repeaters are curved U shaped rails which guide the hot metal from one stand to another. There are
repeaters which can guide them to another stand or to the same stand. They can be manually changed and
moved. There are also slots and rails to move the repeater nozzles from one side of the roll to another.
Fig : Ingots approaching rollers (left) rollers and guide (right)

94. Diameter Total Pass count
10 mm 17
12 mm 15
16 mm 13
20 mm 11
25 mm 10
32 mm 8
Table: Roughing pass count

95. DC continuous mill: It consists of 4 stands having two opposed rollers for 10, 12 and 16 mm. They are all run
by DC shunt motor and connected to PLC panel. PLC stands for programmable logic controls which is a set of
codes and hardware system to automatically control manufacturing operation. The RPM of this panel can be set
manually and synchronized.
Fig: DC continuous mill

96. Pinch Roll: There are 2 pinch rolls whose job is to draw the incoming finished rods towards the flying
shear. They are also connected and operated by the PLC system. The two pinch rolls are called entry
pinch and exit pinch. Both of them are run by DC shunt motor.
HMD sensor: This stands for hot metal detector. Connected to the PLC it senses and measures the
length of rod and signals the flying shear motor to cut rods at specific length. It measures the
temperature too via air bleed pipe. If the metal is not sufficiently hot it stops the flying shear.
Flying shear: It is a mechanical cutting machine with two opposed blades which by rotating cuts the
rods down to specific sizes. It is fully automated and connected with the PLC system. It is run by DC
shunt motor.
Colling bed: It is a 39 meter long bed which stores the incoming rods and cools them in the atmosphere.
The rods are transferred to another place after cooling. The bed is slightly inclined for easy movement.

97. Fig: Pinch roll, flying shear idle, HMD sensor and flying shear in action

98. PLC system: A programmable logic controller (PLC), or programmable controller is an industrial digital
computer which has been ruggedized and adapted for the control of manufacturing processes, such
as assembly lines, or robotic devices, or any activity that requires high reliability control and ease of
programming and process fault diagnosis.
At Elite most of the rolling section is controlled by PLC system. The DC motors are powered from rectifier.
There are 6 stands/panels and a control panel which are collectively used as PLC system at Elite. Turning
on and turning off, controlling RPM, emergency stop, reversing and shifting are some of the operations
done by PLC.
Fig: PLC Panel, control panel, rectifiers, cooling bed and control panel operating

99. TMT box: TMT is special high strength deformed bar which is thermo-mechanically treated. Elite Steel
does not usually produce TMT. But occasionally they may produce TMT.
The bar after leaving the last rolling mill stand is fed to quenching box at a very high speed. In this section, a
rapid and controlled water quenching is performed reducing the temperature of surface drastically from around
950°C to 600°C. Due to higher speed, only outer portion of bar gets quenched. The inner part remains hot only.
The Case due to rapid quenching gets converted in Martensite form. The Microstructure is fine-grained Ferrite-
Pearlite structure at the Core and Martensite at the Case.
Fig : Schematic presentation of TMT bar manufacturing (left), TMT box at Elite (right)

100. Quality Control: Elite Steel tests their EIS G-60 rods at BUET labs and conforms to ASTM, AISI, SAE, and
BSTI standard. They have their own physical and chemical testing laboratory.
Fig : Tensile test of 10 mm G-60 rod.

101. UTM Test

102. Product Specification
Bar nominal
diameter
Nominal weight Cross sectional
area
Approximate length per metric ton
mm Kg/m mm2 Meter Feet
10 0.616 78.5 1621 5318
12 0.888 113.1 1126 3694
16 1579 201.1 633 2077
20 2.466 314.2 405 1330
22 2.985 380.3 335 1100
25 3.854 490.9 259 850
28 4.836 616 207 680
32 6.313 804.2 158 518
Table: Elite Steel product specification

103. Problem 1:
Flow of molten metal outside the column and the mold cavity resulting in metal loss.
Analysis: This problem leads to significant loss of metal which in terms leads to less ingot and which is
caused by failure to set up the molds and the center column properly. Defects or leaks in refractory bricks,
improper alignment of column or even if the tundish does not stay in line with the column or because of
excess turbulence molten steel flows outside its desired path.
Solution: Applying sand in place of leaks or void to solve the problem.
Problem 2:
Gas shortage and cessation of production.
Analysis: The primary source of fuel of the reheat furnace is natural gas which is supplied by national gas
pipeline. If the gas flow rate and pressure is not enough the ingots don’t get enough heat and so the strain
hardening exponent doesn’t come to zero. Due to less temperature the rolling operation becomes very tough
and the rods breaks in different places and rolls become affected.
Solution: This problem was solved by burning coal as substitute fuel.

104. Problem 3:
The biggest and the worst of all problems is entanglement of rods.
Analysis: While passing from one stand to another it frequently bumps with some obstacles or misalignment of
guide/nozzle leads it to another direction which makes the entire piece of rod jammed and entangled which
blocks even the next incoming ingot if not stopped in time.
Solution: By cutting both the rod ends before coming to final stand to facilitate smother movement and to
avoid entanglement.
Problem 4:
The problem with the furnace is very short production time before it must be patched.
Analysis: Life of Refractory lining is low as compared to EAF. Since only 2 furnaces are there they have to be
interchanged and more limestone and forma is required for patching. As the refractory lining is an integral part
of the furnace and the layer of refractory lining wears away with every heat one furnace cannot run indefinitely.
Solution: This particular problem is solved at Elite by re-patching.

105. Conclusion
Steel industry is by volume the largest of all metal production globally. Steel industry in Bangladesh is still
growing and requires intensive investment and attention. Elite Steel comparatively has very little production
but its contribution to national gross production and economy is considerable. Steel industry has come a long
way and new process technology has been adopting periodically. Although Steel production at Elite performs
only few tasks as compared to large scale integrated steel mill and in terms of technology the factory is not
vested with modern continuous caster the factory is a viable place for learning all major steps in steel melting
and flat rolling of rods. These mini mills are also great contributors to environmental protection and energy
savings. They solely depend on recyclable scraps which saves enormous amount of energy and protects
environment. Induction heating is another method of clean and nonpolluting method which also justifies its
use. Finally closely monitored mechanical and chemical properties makes the bars very suitable for RCC
structure which strengthens our country and society eventually.

106. Recommendation
 Mold casting should be replaced with CCM (Continuous casting machine) which will cast billet/bloom/slab
of larger size replacing small ingots.
 Induction furnace has less refining capacity and the scrap has to be pure and very selective. They should
replace it with an electric arc furnace to utilize a wide range of scrap.
 Proper safety measure has to be taken since the factory setup is very imprecise and hazardous. Hot metal
passes through guides and nozzles which is very close to staffs and workers. They have to be properly
arranged.
 Air purity should be improved by replacing the old filter and pump of the fume extraction system with new
ones and operate the fume extraction system at all times to keep the air clean.
 Chemical composition should be properly controlled. If Carbon content increases slightly the ingot becomes
hard and less ductile. The mill stands cannot process this ingot properly.