Stainless Steel Making Process

8/22/2019 Stainless Steel Making Process

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PRESENTATION REPORT ON

Stainless Steel Making Process

Submitted By:

Vipin Rangi (ME/11/747)

Department of Computer Science Engineering and Information Technology

SHRI BALWANT INSTITUTE OF TECHNOLOGYApproved by AICTE, Min of HRD, Govt of India & DTE, Govt of Haryana

Affiliated to DCR University of Science and Technology, Murthal, Sonepat

Meerut Road (Pallri), Near DPS, Sonepat-131001, Haryana


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Abstract

Stainless Steel - an anti-corrosive aesthetics product is produced with unique two stage liquid steel

processing technology. It is the most recycled commodity with varied product life cycle depending

upon usage. Stainless Steel products offer immense market potential for industrial, infrastructure,

transportation, home, architectural and construction applications.

Corrosion resistanceLower alloyed grades resist corrosion in atmospheric and pure water environments, while high-

alloyed grades can resist corrosion in most acids, alkaline solutions, and chlorine bearing

environments, properties which are utilized in process plants.

Fire and heat resistanceSpecial high chromium and nickel-alloyed grades resist scaling and retain strength at high

temperatures.

Products:-

SlabsCast in single strand slab caster of steel melt shop I. Liquid steel is produced through

electric arc furnace-AOD Convertor/VOD-Ladle refining furnace route.

BloomsCast from twin stand bloom caster at Steel Melt Shop II. Liquid steel is produced through

electric arc furnace-AOD convertor- ladle refining furnance route.

Hot Rolled Product

HR CoilsAs cast/ ground slabs are first heated and soaked in reheating furnace, rolled in roughing

mill to intermediate thickness and then to the final thickness in the steckel mill.

HRAP CoilsHot rolled annealed pickled coils are produced after continuous annealing and pickling.

HRAP PlatesNo1 finish plates are produced after annealing and pickling or by cutting hot rolledannealed pickled coils to desired lengths. Hot Rolling Complex comprises of 4-Hi Twin

stand Hot Steckel Mill and Tandem Strip Mill

ii


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CERTIFICATE

This is to certify that the Seminar Topic entitled as Stainless Steel Making Process andsubmittedby

Vipin Rangi having Roll No ME/11/747, embodies the bonafide work done by his/her under my

supervision.

Place: delhi

Signature of the Supervisor

Date: 14th October 2012

iii


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TABLE OF CONTENTS

1. INTRODUCTION.2

2. DESCRIPTION ..... 33. CONCLUSION.4

4. REFERENCES..5

1


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INTRODUCTION

The work-hardening property of austenitic grades, that results in a significant strengthening of the

material from cold-working alone, and the high strength duplex grades, allow reduced material

thickness over conventional grades, therefore cost savings.

Stainless Steel - an anti-corrosive aesthetics product is produced with unique two stage liquid steel

processing technology. It is the most recycled commodity with varied product life cycle dependingupon usage. Stainless Steel products offer immense market potential for industrial, infrastructure,

transportation, home, architectural and construction applications.

Benefits of Stainless Steel

Corrosion resistanceLower alloyed grades resist corrosion in atmospheric and pure water environments, while high-

alloyed grades can resist corrosion in most acids, alkaline solutions, and chlorine bearing

environments, properties which are utilized in process plants.

Fire and heat resistanceSpecial high chromium and nickel-alloyed grades resist scaling and retain strength at high

temperatures.

HygieneThe easy cleaning ability of stainless makes it the first choice for strict hygiene conditions, such as

hospitals, kitchens, abattoirs and other food processing plants.

Aesthetic appearanceThe bright, easily maintained surface of stainless steel provides a modern and attractive appearance.

Strength-to-weight advantage Ease of fabrication

Modern steel-making techniques mean that stainless can be cut, welded, formed, machined,

and fabricated as readily as traditional steels.

Impact resistance

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The austenitic microstructure of the 300 series provides high toughness, from elevated temperatures

to far below freezing, making these steels particularly suited to cryogenic applications.

Long term valueWhen the total life cycle costs are considered, stainless is often the least expensive material option.

Stainless Steel - an anti-corrosive aesthetics product is produced with unique two stage liquid

steel processing technology. It is the most recycled commodity with varied product life cycle

depending upon usage. Stainless Steel products offer immense market potential for industrial,

infrastructure, transportation, home, architectural and construction applications.

Types of Stainless Steel:-

Stainless Steel grades are essentially alloys of iron with more than 10.5% chromium. These

grades may contain additional elements of nickel, manganese, carbon, nitrogen and silicon.

They can further be modified for special purposes by addition of molybdenum, titanium,

niobium, silicon, sulphur etc. A wide range of these grades have been developed based on

specific requirements. These are classified into following categories based on their microstructure:

o Austenitic Stainless SteelAustenitic Stainless Steel grades are characterized by superior corrosion and oxidation

resistance,weld ability, ductility and toughness compared to ferritic and martensitic Stainless

Steel grades for similar levels of chromium. Austenitic Stainless Steel grades exhibit excellent

resistance to atmospheric corrosion. They effectively withstand attack of organic acids (e.g.

acetic, lactic, citric etc.), exhibit good resistance to oxidizing acids (e.g. nitric acid) and fair

resistance to mineral acids (e.g. sulfuric acid).These grades are well suited for severe forming.

Some grades work harder to a high degree while others have been developed to minimize this

tendency. Work hardening is advantageous in certain cases where high strength is required.

Austenitic Stainless Steel grades are nonmagnetic in annealed condition but depending on

composition, they may become mildly magnetic when cold worked. These Stainless Steel

grades possess good high temperature properties such as creep strength and resistance to

oxidation or scaling. They also exhibit excellent low temperature ductility and impact strength.

Austenitic Stainless Steel grades can be readily fabricated by bending, drawing, spinning,

punching, drilling, machining and welding and can be readily polished to a high finish. These

attributes make them very versatile and popular for diverse applications in a variety of

industries. There are two broad categories of Austenitic Stainless Steel chrome nickel (300

Series) and chrome manganese (200 Series). Currently, chrome-nickel is the largest produced

Stainless Steel category globally. Typical applications for this category include food

processing, chemical plants, pharmaceutical equipment, hospitals, textile, architectural, buildingconstruction, kitchenware, consumer durables etc. Chrome-manganese Stainless Steel is the

fastest growing of all Stainless Steel categories on account of its high performance to cost ratio.

Its applications include kitchenware, cutlery, sinks, automotive trim, architectural, buildings,

furniture, buses, trains and ornamental tubes.

o Martensitic Stainless SteelMartensitic Stainless Steel grades are plain chromium grades containing 11.5 % to 18% of

chromium with relatively high carbon content (0.1% 1.2%). Initially developed for cutlery,

these are well suited for applications requiring high hardness and resistance to abrasion and


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erosion. These grades are magnetic and display fair cold forming characteristics. Although

these can be hardened by air cooling, oil quenching is sometimes used to assure uniform

hardening. These grades can be welded but require stress relieving after welding. They exhibit

their best corrosion resistance in the hardened condition and perform well in mildly corrosive

environments. Martensitic Stainless Steel grades are commonly used for knife blades, turbine

blades, surgical instruments, fasteners, shafts, spindles, valves and pins.

o Ferritic Stainless SteelFerritic Stainless Steel grades are non-hardenable plain chromium grades with chromium

content varying from 10.5% to 28% and with low carbon content. These are magnetic and

exhibit a better resistance to corrosion than martensitic grades. These grades are employed in

applications where the desired formability, weldability and corrosion resistance is between

those of martensitic and austenitic types. The ferritics can be polished or buffed to achieve high

luster.

o Duplex Stainless SteelDuplex Stainless Steel grades contain relatively high chromium (between 18% and 28%) and

moderate amounts of nickel (1% to 8%). This combination of ferritic and austenitic structures is

called duplex. Many of these grades contain molybdenum (1% to 5%) and nitrogen (0.05% to0.3%). Some duplex Stainless Steel grades also contain manganese (up to 5%), copper (up to

2%) and tungsten (up to 2%). These grades exhibit high resistance to stress, corrosion cracking

and chloride ion attack and have higher yield strength than that of austenitic or ferritic steel

grades. These properties combined with suitable design lead to material saving. High quality

fabrication and welding are possible if the operator is trained well. These grades are used in

marine applications, offshore platforms, paper and pulp industry, chemical, petrochemical and

desalination plants.


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DESCRIPTION

Products :-

Krome 16+

Krome16+ from Jindal Stainless is a branded Stainless Steel in coil form conforming to AISI 430

grade. It is a ferritic solution offering many advantages in the manufacture of Cookware and

Utensils.

Chromium (not Nickel, as is sometimes imagined) is the key ingredient for the Corrosion

Resistance of Stainless Steels. Krome 16+ contains minimum 16% Chromium for high corrosion

resistance.

Advantages of Krome16+

i. Superior thermal conductivity over 200 and 300 series Stainless Steels. This help inconducting heat more evenly than austenitic grades resulting in heating the food must faster

and saving fuel in cooking.

ii. Excellent high temperature oxidation resistance upto 800C making it less prone to scalingthan austenitic grades.

iii. Expands and Distorts less than austenitic grades when heated due to low thermal expansion.iv. No risk of delayed crakingunlioke austenitic grades.v. Costs less since it has no Nickel, Copper and has very low Maganese.

vi. Stable price.vii. Brilliant & Lustrous asethetic appeal.

viii.

Its lower density leads to 2 - 3% more utensils of same size per ton of sheet compared toaustenitic grades.

Ease of Fabrication

i. Exhibits excellent deep drawability.ii. Very well suited to all methods of forming Stainless Steels including bending, drawing,

stretch forming and spinning.

iii. Easier to cut and work than austenitic grades.iv. Requires less powerful machines for fabrication.v. Generates less tool wear.

vi. Comparatively lesser spring back than austenitic grades after cold forming.vii. Higher yield in utensil manufacture.

Chrome Manganese

Share of Cr-Mn grade has witnessed the fastest growth in global Stainless Steel

consumption in recent past Helps in sustainable growth of Stainless Steel through minimizing

substitution by other competing material.


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Typical Applications

Due to their good formability, weldability and corrosion resistance, JINDAL STAINLESS 200

series grades can be used for applications as detailed below:

CateringPressure cookers, deep drawn utensils, kitchen sinks, milk cans, &

204 Cu food processing, water filters, storage vessels

Shallow/medium drawn utensils, tableware, catering,Stand for water

filters, flasks

Consumer DurablesWhite goods/house hold appliances, washing machines, microwave

ovens, & 204 Cu dish washers, thermo-ware, mobile case and parts

White goods dry applications, steel furniture, decorative tubing

Architecture,

Building

Outdoor non-coastal, door window frames, elevators& Construction

& 204 Cu

Indoor decoration, hand rails, ornaments, tubes, Door frames,

handles and knobs

Automotive Motor cycle rim, wheel cover, wiper arm, bus body, & 204 Cu railcar

Interior decorative

Industry Wine, Bear, Sugar industry & 204 Cu.

Product Portfolio

Continuous Cast Products Slabs

Cast in single strand slab caster of steel melt shop I. Liquid steel is produced through electric arcfurnace-AOD Convertor/VOD-Ladle refining furnace route.

BloomsCast from twin stand bloom caster at Steel Melt Shop II. Liquid steel is produced through electric

arc furnace-AOD convertor- ladle refining furnance route.

Hot Rolled Product HR Coils


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As cast/ ground slabs are first heated and soaked in reheating furnace, rolled in roughing mill to

intermediate thickness and then to the final thickness in the steckel mill.

HRAP CoilsHot rolled annealed pickled coils are produced after continuous annealing and pickling.

HRAP PlatesNo1 finish plates are produced after annealing and pickling or by cutting hot rolled annealed pickled

coils to desired lengths. Hot Rolling Complex comprises of 4-Hi Twin stand Hot Steckel Mill and

Tandem Strip Mill with a total capacity of 720,000 tons per annum & 350,000 tons per annum

respectively. Hot Steckel Mill consists of a Roughing Stand, two Finishing Stand and a Walking

Beam Slab Reheating Furnace. The Tandem Strip mill comprises of Reheating Furnace, Roughing

Stand, five Finishing Stands and Down Coiler. The complex also consists of Plate Annealing &

Pickling facilities along with Shot Blasting, Straightening & Leveling equipment to produce

Stainless Steel Plates of various grades.

Cold Rolled ProductsCold rolled coils and sheets are produced after being processed in the 20 Hi Mill, continuous anneal

& pickle line, skin pass mill slitting line and cut to length lines. Absolute flat sheets are produced

after being put through the Voss leveller. Sheets & cold rolled coils are available in different

finishes 2D, 2B, No3, No4 and BA.

Cold Rolling Complex has a capacity to produce 275,000 tons per annum of Cold Rolled Stainless

Steel Flat products.

The complex is equipped with four 20 Hi-Sendzimir Cold Rolling Mills, Four continuous Anneal

and Pickle lines, three of these are equipped with Electrolytic Pickling, one bright Annealing Line,

three Coil Preparation Lines, four Slitting Lines, one Leveling and Sheet Shearing Line with

associated facilities.

JSL STAINLESS is fully equipped to produce material with No. 1, 2D, 2B, BA and No. 4 and

customized surface finish. It can also produce other specialized finishes such as moon rock, hammer

stone, and honey comb.

Speciality ProductsSpecialty Product Complex has a capacity of 25,000 tons per annum of precision cold rolled strips.

This complex processes mainly martensitics Stainless Steel for razor blade manufacturing.

The Specialty Product Complex comprises of processing equipment, primarily for annealing,

rolling, and finishing. There is an option of using either a Bell Annealing or a Bright Annealing or

even Pull- through Annealing depending on the grade and finish of Stainless Steel being produced.

4-Hi mills and 20-Hi mills are used for reduction rolling to thinner gauges with close thickness

tolerances. To impart various finishes in the final products, the complex has Strip Grinding Line,

Skin Pass Mill and Tension Leveler. Such product then passes through the Precision Slitters to

achieve precise dimensions.


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The razor blade cold rolled strips of up to 0.076mm thickness are produced in this complex and

supplied to leading Indian and International razor blade manufacturers.

Ferro AlloysMining of ore is key to the integration process. JSL Stainless has chrome ore open cast mines at

Sukinda, Orissa to support 40,000 tons per annum capacity Ferro Chrome plant at Vizag. In

addition to this, JSL Stainless has acquired Chrome mines outside India and is further exploring

options to support its Ferro Alloys operations.

In the first phase of the Orissa project, JSL Stainless has set up Captive Power plants, Coke Oven

batteries and Submerged Arc Furnaces to produce Ferro Alloys.

As part of this project, 2 x 60 MVA furnaces, largest in India, with capacity of 150,000 tons per

annum are already in operation and producing High Carbon Ferro Chrome (HCFC). These state-of-

the-art furnaces and the Briquetting Press have been supplied by SMS DeMAGAG, and

KopernMaco of Germany respectively. The waste heats of these semi closed furnaces are utilized to

generate 13MW power.

The Ferro Alloys complex also comprises of 1 x 27.6 MVA Ferro Manganese and2 x 27.6 MVA

Silico Manganese Furnaces supplied by Sibeltherm, Russia to produce 100,000 tons per annum.

Stainless Steel Making Process

The manufacture of stainless steel involves a series of processes. First, the steel is melted,

To make stainless steel, the raw materialsiron ore, chromium, silicon, nickel, etc.are melted

together in an electric furnace. This step usually involves 8 to 12 hours of intense heat. Next, the

mixture is cast into one of several shapes, including blooms, billets, and slabs.

and then it is cast into solid form. After various forming steps, the steel is heat treated and then

cleaned and polished to give it the desired finish. Next, it is packaged and sent to manufacturers,

who weld and join the steel to produce the desired shapes.

Melting and casting


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The raw materials are first melted together in an electric furnace. This step usually requires8 to 12 hours of intense heat. When the melting is finished, the molten steel is cast into

semi-finished forms. These include blooms (rectangular shapes), billets (round or square

shapes 1.5 inches or 3.8 centimeters in thickness), slabs, rods, and tube rounds.

Forming

Next, the semi-finished steel goes through forming operations, beginning with hot rolling,in which the steel is heated and passed through huge rolls. Blooms and billets are formed

into bar and wire, while slabs are formed into plate, strip, and sheet. Bars are available in all

grades and come in rounds, squares, octagons, or hexagons 0.25 inch (.63 centimeter) in

size. Wire is usually available up to 0.5 inch (1.27 centimeters) in diameter or size. Plate is

more than 0.1875 inch (.47 centimeter) thick and over 10 inches (25.4 centimeters) wide.

Strip is less than 0.185 inch (.47 centimeter) thick and less than 24 inches (61 centimeters)

wide. Sheet is less than 0.1875 (.47 centimeter) thick and more than 24 (61 centimeters)

wide.

Heat treatment

After the stainless steel is formed, most types must go through an annealing step. Annealingis a heat treatment in which the steel is heated and cooled under controlled conditions to

relieve internal stresses and soften the metal. Some steels are heat treated for higher

strength. However, such a heat treatmentalso known asage hardeningrequires careful

control, for even small changes from the recommended temperature, time, or cooling rate

can seriously affect the properties. Lower aging temperatures produce high strength with

low fracture toughness, while higher-temperature aging produces a lower strength, tougher

material.

Though the heating rate to reach the aging temperature (900 to 1000 degrees Fahrenheit or 482 to537 degrees Celsius) does not effect the properties, the cooling rate does. A post-aging quenching

(rapid cooling) treatment can increase the toughness without a significant loss in strength. One such

process involves water quenching the material in a 35-degree Fahrenheit (1.6-degree Celsius) ice-

water bath for a minimum of two hours.

Stainless steel making process

Hot Rolling


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Hot Rolling complex comprises of 4-Hi twinstand hot steckel mill and tandem strip mill with a total

capacity of 720,000 tons per annum & 350,000 tons per annum respectively. Hot steckel mill

consists ofa roughing stand, two finishing stand and a walking beam slab reheating furnace. The

tndem strip mill comprises of reheating furnace, roughing stand, five finishing stands and down

coiler.

The hot rolling process begins at the reheat furnace where the slabs are heated to between 1 100 and

1 300C, depending on the stainless steel grade. The slabs are then rolled on a reversing four high

mill to gauges between 65 and 25mm. Thinner gauges are rolled down further on the Steckel mill.

Once the predetermined gauge is reached, the material can either be coiled (black coil, also known

as hot band, HR or HRA) or cut into plate (black plate (HRA)). This is our second range of saleable

products.

Coil mass is between 20 and 30 tons and the thickness is generally between 3mm and 8mm.

Plate thickness can range between 3 mm and 65 mm.

Annealing and Pickling

The hot rolled products are softened (annealed) and descaled (pickled with acids) to produce a No. 1finish product. This product has a light grey matt surface finish. No. 1 coil and plate are also

saleable products.

Hot Rolling Process

Cold Rolling

The hot rolled, annealed and pickled coils are passed through rolls at room temperature, a process

referred to as cold rolling. This helps in thinning the hot rolled coils further. The sheets and strips of

reduced thickness are again subjected to the annealing and pickling processes. A final cold rolling

step then prepares the Stainless Steel for further processing. The product obtained at the end of the

cold-rolling process is extensively used in aesthetic applications as the thinned stainless steel yields

to further polishing and buffing with consummate ease.


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Cold rolling of the No. 1 coils takes place on one of our four Sendzimer mills (Z-mills), which

produce smooth, shiny finished, cold rolled stainless steel. The thickness range of the cold rolled

product is between 0.2mm and 6mm.

The material is then annealed (softened) and pickled (and passivized), before it is processed through

the skin pass mill, to ensure a smooth surface, known as a 2B finish.

Alternatively, the cold rolled material can be processed to a bright annealed (BA) finish. This is

achieved by annealing in a vertical furnace with an inert atmosphere, to retain the bright surface

imparted by the cold rolling

process.

These cold rolled stainless

steel coils can then be cut

into smaller coils or sheets,

or slit to narrower widths

before being packed and

shipped to our customers.

PROCESSING UNITS IN DETAILS

I. Furnaces: Preheating (PHF) and Heating (HF):

After the completion of production of slabs in SMS, they come to the steckel mill for hot rolling.

Before rolling they are heated to approx 1200oC temp by the help of preheating and heating furnace.

How heating takes place in these furnaces - Firstly, the hydraulic controlled gate of preheating

furnace opens and a robotic arm lift the slab and put it into the furnace and after that gate closes. In

the furnace there is a hydraulic controlled walking beam system through which slab moves in the

furnace and after heating up to 300-600C, there is electrically operated robotic arm which take out

the slab from furnace and put it on the conveyer. Then slab goes to heating furnace where heating

takes place in two zones heating and soaking

Heating ZoneIn this zone there are burners installed at the top and bottom which heats the coil

from top and bottom.

Soaking Zone - In this zone slab is kept for some time so that slab get heated up to the core i.e. core

and surface both get heated to the required temp which is around 1200C.

When final temp is acquired and the system used for putting, moving and taking out the slab is

similar to the preheating furnace.

Why preheating is doneIn JSL preheating is done to increase the production rate. If only heating

furnace is used it takes more time to heat a coil than to process it in steckel mill, so preheating

furnace is used which heats the slab to 300-600C temp and now it takes less time to get heated in

heating furnace.

Capacity: 85 MT/hr for heating furnace only (without pre-heating furnace) and 125 MT/hrwith

preheating and heating furnace


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II. Descaling Unit:

Primary descaling unit :o Objective : Remove the primary scales on the slab

surface (mostly Fe3O4 oxides)

o High pressure water jets are applied from both the topand bottom nozzles at 205-210 bar pressure

Secondary descaling unit:o Objective : Remove the secondary scales from the slab

surface (mostly Fe2O3 oxides)

o High pressure water jets applied at a pressure of 205-210 bar Scale loss: 0.35-0.5% of slab weight.

III.4 HI Roughing Mill

After descaling unit slab reach to the roughing mill which is a 4 HI reversible mill. There slab is

rolled from 200mm to 32-40mm which depends on the grade. It is called roughing mill as the gap

between its rolls is controlled by automatic gauge control and mechanical screws which have low

accuracy, so this mill gives a rough thickness, for example grade 430 is rolled to 32 mm through

roughing moll i.e. this mill gives a thickness around 32 mm not exactly. The rolls of this mill are

made of S.G Iron. In this mill there is problem of variation in width ranging +10mm/ -5mm.

IV. Steckel Mill

After roughing mill it reaches to the steckel mill where it is rolled to the final thickness.

Steckel mill has two hot coilers: entry hot coiler and exit hot coiler. These two coilers are used to

provide space for accommodating the entire length of the coil for rolling in Steckel mill and to

maintain temp of coil depending on grade of steel rolled

200 series : 1050 C, 300 series : 1050 C 400 series : 900-950 C.

These hot coilers have 6 burners : 4 running, 2 standbye and LVFO is used as a fuel in these

burners. Between these two hot coilers twin stand 4 hi reversing mills has been installed. Minimum


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thickness that can be rolled on this mill is around 5-6 mm. Number of passes through steckel mill

are depend upon final product. If final product requirement is plate then only one pass is required

but for coils either 3 or 5 passes are required. Thickness in each pass is controlled or governed with

the help of X-ray & hydraulic auto gauge control. Basically thickness is measured with the help of

X-rays which gives a feedback to hydraulic auto gauge control, accordingly automatically distance

between the rolls is adjusted. Also for the smooth & accurate movement of rolls servo valves has

been installed. Average speed of steckel mill is around 3-4 m/sec & it varies according to grades

rolled. Work rolls are changed after every 250 MT of rolling.

According to costumer demand for coils, positive crown or negative crown rolls are used for rolling

in steckel mill. Here in JSL more demand is for positive crown coils due to which negative crown

rolls are used

How thickness is measured through X-rayX-ray can pass through materials but in doing so they

lose energy. If the initial intensity is known, the thickness of material can be determined by

measuring the intensity remaining after going through the material. Therefore, this type of a gauge

is composed of an emitter usually placed under the strip and a receiver, located on the top of strip.(These gauge are calibrated with standard plates of various alloys to be rolled).

Defects generated:

Scratches at head and tail end generated from hot coiler Gauge variation Crown Camber Wedge

VI. Cooling unit:

Cooling is done after exit from the Steckel mill Laminar cooling with water jets are done for grades : JSL-AUS, 446, 439, 436

For other grades, no cooling is done Finish Rolling temp is generally > 900 C Coiling temp without laminar cooling is around 800-850 C; while CT with cooling is

around 600-700 C

Overall line yield from Steckel Mill rolling unit: 97.5% (target); actual: 98% For 400 series coils, yield: 96-97% For 200, 300, 400 series in plates of thickness > 12 mm : 99.5% For coils in 300 series : 98.5% For coils in 200 series : 98.5%


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STECKEL MILL

A Steckel mill, also known as a reversible finishing mill, is similar to a reversing rolling mill except

two coilers are used to feed the material through the mill. One coiler is on the entrance side and the

other on the exit side. The coilers pull the material through the mill, therefore the process is more

similar to drawing than rolling. The material is fed back and forth through the mill until the desired

thickness is reached, much like a reversing rolling mill.

It is also used to process steel slabs into hot rolled coil (HRC). The Steckel mill allows the rolling of

a large slab by providing heated reels on both sides of the mill to store the increased length

produced during rolling. These drums allow for additional heat retention and thermal consistency in

the rolled piece, which in turn produces improved uniformity throughout the rolled product. A

furnace is provided in both sides of the mill, which covers the mandrels each in one side uponwhich the slab is rolled after every complete pass. Output from Steckel mill varies from 2.5 to 3mm.

A cutter mechanism is also provided in this mill to cut the irregular head and tail of the incoming

slab.

In the Steckel mill, several passes have to be taken to get the desired reduction. The Steckel mill has

quality problems due to temperature losses. The rate of production in a Steckel mill is lower than a

tandem mill as steckel mill is reversible.

In JSL, Hot rolling comprises of Hot Steckel Mill and Tandem Strip mill. The hot steckel mill

comprises of slab reheating walking beam furnace, 4 Hi reversing roughing mill, 4 Hi reversing

Steckel Mill equipped with Hot Coilers on both sides and a down coiler. Slabs are rolled to hot

rolled coils and plates. The mill is equipped with level-2 automaton system consisting of automatic

hydraulic gap setting, roll bending system, automatic pass scheduling and mill setup, automatic

sequencing, mill supervisory system automatic X-ray gauge control and descaling unit. The mill is

capable of rolling plates and coils upto 1250 mm width weighing upto 18 MT .

GENERAL LAYOUT OF STECKEL MILL

STRAPPING OF COIL


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CAPACITY: 125 TPH (with preheating f\c) and 85 TPH (w\o preheating f\c)

3


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CONCLUSION

Stainless Steel is an anti-corrosive aesthetics product is produced with unique two stage liquid steel

processing technology. It is the most recycled commodity with varied product life cycle depending

upon usage. Stainless Steel products offer immense market potential for industrial, infrastructure,

transportation, home, architectural and construction applications.Lower alloyed grades resistcorrosion in atmospheric and pure water environments, while high-alloyed grades can resist

corrosion in most acids, alkaline solutions, and chlorine bearing environments, properties which are

utilized in process plants.The bright, easily maintained surface of stainless steel provides a modern

and attractive appearance.

Stainless Steel grades are essentially alloys of iron with more than 10.5% chromium. These grades

may contain additional elements of nickel, manganese, carbon, nitrogen and silicon. They can

further be modified for special purposes by addition of molybdenum, titanium, niobium, silicon,

sulphur etc. A wide range of these grades have been developed based on specific requirements.

These are classified into following categories based on their micro structure:

Austenitic Stainless Steel grades are characterized by superior corrosion and oxidation

resistance,weld ability, ductility and toughness compared to ferritic and martensitic Stainless Steel

grades for similar levels of chromium.Martensitic Stainless Steel grades are plain chromium grades

containing 11.5 % to 18% of chromium with relatively high carbon content (0.1%1.2%).

4


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REFERENCES

JSL STAINLESS website: www.jslstainless.com Google www.madehow.com www.ssina.com
http://www.jslstainless.com/http://www.madehow.com/http://www.ssina.com/http://www.ssina.com/http://www.madehow.com/http://www.jslstainless.com/

Stainless Steel Making Process

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