S T E E L

Steel is essentially a combination of iron and carbon.

Carbon content of common grades ranges from a few hundredths to about one per cent.

Steels also contain varying amounts of other elements, principally manganese, phosphorus, sulfur, and silicon, which are always present if only in trace amounts.

These and some 20 other alloying elements, which are added in various combinations as desired, determine the ultimate properties and characteristics of the particular steel to a great extent .

CLASSIFICATION OF METALS

CLASSIFICATION OF FERROUS METALS

Low Alloy (<10 wt%)• Low Carbon (<0.25 wt% C)• Medium Carbon (0.25 to 0.60 wt

%)• High Carbon (0.6 to 1.4 wt%)

LOW CARBON STEEL• A.k.a Plain carbon steels, ordinary steels, or straight carbon steels • small amounts of Mn• Most abundant grade of steel• greatest quantity produced• least expensive.• High Strength• Not responsive to heat treatment; cold working needed to improve the strength.• Good Weldability and machinability

High Alloy• Stainless Steel (>11 wt% Cr)• Tool Steel

EFFECTS OF ALLOYING ELEMENTS ON STEELELEMENT BENEFITSMANGANESE • STRENGTH & HARDNESS

• DECREASE DUCTILITY & WELDABILITY

PHOSPHORUS • STRENGTH & HARDNESS• DECREASE DUCTILITY• TOUGHNESS OF STEEL

SULPHUR • DECREASE DUCTILITY & WELDABILITY• TOUGHNESS OF STEEL

SILICON • PRINCIPAL DEOXIDIZER• IMPROVES SURFACE QUALITY

COPPER • CORROSION RESISTANCE[Cu>0.20%]

NICKEL • HARDENABILITY & STRENGTH • FERRITE STRENGTHENER

MOLYBDENUM • ENHANCES CREEP RESISTANCE OF LOW ALLOY STEEL

•Phosphorus- 0.04% (max)•Silicon- 0.35%•Chromium- 3.99%•Boron- 0.005%•Lead- 0.15-0.35%•Nitrogen- 0.004%•Aluminium- 0.95-1.3%

PERCENTAGE OF CONSTITUENTS IN STEEL

Type of Structural Steels according to chemical composition

• Carbon-manganese steels• A.k.a mild structural steel• primary chemical components : carbon+iron+manganese• least expensive• quite adequate strength and ductility • most widely used grades. • High-strength low-alloy (HSLA) steels• recent development in steelmaking• The higher strength achieved by adding small amounts of additional chemical elements • High-strength quenched and tempered alloy steels• the increase in strength is achieved through heat treatment• is available only in plate form, up to 6 inches thick.

MAKING OF STEEL

IT IS THEN POURED IN MOLDS TO OBTAIN STEEL

DEOXIDIZER SUCH AS Al OR FERROSILICON IS ADDED TO CONTROL EVOLVED GAS DURING SOLIDIFICATION

FERROALLOYS ARE ADDEDFOR DESIRED ANALYSIS

MOLTEN METAL IS ALLOWED TO FLOW THROUGH TAP

HEATED TILL DESIRED CARBON CONTENT OBTAINED

SLAG FLOATS OVER HEAVY METAL WHEN OXYGEN IS SUPPLIED CAUSING OXIDATION OF P,Mn AND Si

MOLTEN PIG IRON ADDED

MELTED USING FLAME ON ITS SURFACE

SCRAP+LIMESTONE+IRON ORE ADDED

OPEN-HEARTH FURNACE: • Furnace capacities range from 100 to 500 tons per melt.• require 4 to 10 hours of furnace time.

BASIC OXYGEN FURNACE:

SAME AS OPEN HEARTH

BUT OXYGEN IS ADDED TO INCREASE SPEED OF REFINING

PROCESS

STEELS OF 300 TONS MADE IN LESS THAN 1 HOUR

IT HAS CLOSED BOTTOM,REFRACTORY LINED VESSEL IN WHICH PIG AND SCRAP IRON ARE ADDED

DURING OXYGEN BLOW LIME AND FLUORSPAR ARE ADDED WHICH FORM SLAG

OXYGEN IS SUPPLIED THROUGH WATER COOLED PIPE CAUSING RAPID OXIDATION OF MN,C AND SI

HOT MELTED STEEL TAPPED IN VESSEL AND DEOXIDIZERS ,ALLOYING ELEMENTS ARE ADDED.THEN MOULDED

Iron ore

fluxes coal

Blast furnace

LD1

LD2

Slab casterWire mill

slabs

slabsCold roll coils

Cold roll mill

Sinter plant

Coke plant

Steel making LD1/LD2Iron making process

Hot strip mill

Hot roll coils

Merchant mill

MAKING OF GALVANISED SHEETS

Steel Finishing : Hot working

MATERIALS AND THEIR SIZES AVAILABLE IN

MARKET

IS 808 : Nominal dimensions and mass of beam, column, channel and equal and unequal angles can be confirmed to the standard values given.

IS 1730Type 1.1: Hot rolled steel plates (thickness 3 – 60 mm) used in

building frame structures. Dimensions: t= 3-60. The standard

steel grade is ≤ S355.

IS 808IS 1730

Type 2.1: Hot rolled open H, I, U, L - steel sections and wide flats are hot-rolled sections used in frame

structures. Dimensions: I 80-600, H 100-600, U

80-400, L 40-200, L 65x50 - 200x150, T 30-140 and wide steels:160-500, t=5-40.. The

standard steel grade is ≤ S355

IS 808Type 3.1: Cold formed hollow steel

sections Circular, square and rectangular

sections are used in building frame structures, made of hot-rolled

steel strip by cold-rolling . Dimensions: Square HS: 25x2 -

300x12,5. Rectangular HS: 50x25x2 - 400x200x12,5 and Circular HS:

21,3x2 - 711x60 The standard steel grade is ≤ S355

IS 1732Type 4.1: Hot-finished hollow

steel sectionsCircular, square and rectangular

sections are used in building frame structures, made of

hotrolled steel Dimensions: Square HS: 40x3 - 400x20.

Rectangular HS: 50x30x3,2 - 500x300x20 and

Circular HS: 21,3x2 - 711x60. standard steel grade is ≤ S355.

IS 1732Type 5.1: Steel for the

reinforcement of concrete weldable,

Dimensions: D= 6-50. The standard steel

grade is ≤ B500.

IS 808IS 12778

Type 1.2: Welded plated beams; sections made of welded hot-rolled steel plates used in building frame

structures. Sections are prefabricated and erected on-site by steel

contractors. Dimensions: H = 150-600, B1 =

110-600, B2 = 140-700, d = 5-12, t1/t2 = 6-60. The standard steel grade is ≤S355

India is the world's largest producer of crude steel, and is currently doubling its production capacity.

STEEL MANUFACTURING COMPANIES IN INDIA

REFERENCES• < http://www.kinnaristeel.com/seamless-pipes>• Indian steel prices[online]<http://www.meps.co.uk/indiansteelpriceindex>• Properties and applications of materials handbook[online]http://nptel.ac.in/courses• Steel as a construction material pdf• CPWD for steel[online]http://cpwd.gov.in/Publication/Specs2009• chemical composition of structural steel handbook• https://law.resource.org/pub/in/bis/S03/is.808.1989.pdf• Carbon steel pdf[online]< https://www.metabunk.org>• <https://www.google.co.in/steelmakingtatasteel>

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