2. WHAT IS FERROUS METALS?
METAL: metal is an element, compound or alloy that is a good conductor
of both electricity and heat.
FERROUS: Ferrous metals are metals that contain iron. E.g. Steel (iron
and carbon)
ALLOY: mixtures of two or more metals formed together with other
elements/materials to create new metals with improved Mechanical
Properties and other properties of the base metal.
• The amount of carbon will determine the hardness of the steel.
• The carbon amount ranges from 0.1% to 4%.
Ferrous Metal : alloy metals that contains iron ( Primary base metal is
iron)
Non-ferrous Metal : alloy metals that do not contain iron
Primary base metal does not contain iron)
4. Metals Properties Uses
1. Pig Iron
(contains 92% iron, upto 3.5%
carbon & other
impurities )
•Can be hardened but not
tempered
•Can not be magnetized
•Can not be welded
•Does not rust
•Difficult to bend
•Hard and brittle
•Neither ductile nor
malleable
•Melts easily
•Possesses high compression
strength but weak in tension
•Making steel…Modern steel
mills and iron plants transfer
the molten iron to a ladle for
immediate use in the steel
making furnaces or cast it
into pigs on a pig-casting
machine for reuse or resale.
Pig iron: the intermediate product of smelting iron ore with a high-carbon fuel such as
coke, usually with limestone as a flux
Types of iron:
5. Metals Properties Uses
2. Cast Iron •If placed in salt water, it becomes
salt
•Can be hardened by heating
•Cannot be magnetized
•Does not rust easily
•Fusible
•Hard but it is brittle
•Isn‟t ductile & cannot be adopted to
absorb shocks
•Melting temp is about 1250 deg
Celsius
•Shrinks on cooling
•Structure is granular & crystalline
•Lacks plasticity
•Weak in tension & strong in
compression
•2 pieces of cast iron cannot be
connected by the process
•Making cisterns, water pipes, gas
pipes and sewers, sanitary fittings.
•Making ornamental castings such as
brackets, gates, lamp posts, spiral
staircases etc.
•Making parts of machinery
•Manufacturing compression
members like columns, bases o
columns, etc.
•Preparing agricultural implements
•Preparing rail chairs, carriage wheels
etc.
Cast iron: is derived from pig iron
◦ White cast iron is named after its white surface when fractured, due to its carbide
impurities which allow cracks to pass straight through.
◦ Grey cast iron is named after its grey fractured surface, which occurs because the
graphitic flakes deflect a passing crack and initiate countless new cracks as the material
breaks.
6. Wrought iron: iron alloy with a very low carbon content, in comparison to steel, and has
fibrous inclusions (slag)
◦ tough, malleable, ductile and easily welded
Metals Properties Uses
3. Wrought Iron •Becomes soft at white heat
& can be easily welded.
•Can be used to form
temporary magnets.
•Fuses with difficulty,
therefore cannot be used for
castings.
•Ductile, malleable & tough.
•Moderately elastic.
•Unaffected by saline water
•Resists corrosion
•Melting point is 1500 deg
Celsius
•Clear bluish colour with a
high silky luster and fibrous
appearance.
•replaced at present to a
very great extend by mild
steel
•used where a tough material
is required.
•Used for rivets, chains
ornamental iron work,
railway couplings, water and
steam pipes, row material for
manufacturing steel, bolts and
nuts, horse shoe bars,
handrails, straps for timber
roof trusses, boiler tubes,
roofing sheets, armatures,
electro-magnets, etc
7. Intermediate stage between wrought iron and cast iron
Wrought Iron - Carbon content: not greater than 0.15%
Steel - Carbon content: 0.15% to 1.5%
Cast Iron - Carbon content :2% to 4%
9. Raw materials for extraction of iron:
Iron Ore
•Abundant, makes up 5% of earth‟s crust
•Is not found in „free state‟, must be found in rocks and
oxides, hence Iron ore.
•After mining, the ore is crushed and the iron is
separated, then made into pellets, balls, etc.
Limestone
• Limestone (calcium carbonate) is used to remove
impurities.
Coke
• Coke is formed by heating coal to 2100*F (1150 C), then
cooling it in quenching towers.
• It`s used: . Generates high heat, needed in order for
chemical reactions in iron making to take place.
10. Process of blast furnace:
Ore, coke, and limestone are “charged” in layers into the top of a blast
furnace
Ore is the source of the iron , Coke is the source of the carbon (coke is
derived from coal, by heating in a coking oven)
Limestone acts as a fluxing slag to remove impurities.
1900degree C-air blown into bottom of furnace, burns oxygen off the iron
oxides, causing temperature in furnace to get above the melting point of
iron (approx 3000 degrees)
Molten iron sinks to bottom of furnace, where it is tapped off from furnace
and cast into large ingots called “pigs. Pigs iron contain high carbon content
(4% or so), plus many impurities, such as sulphur and silica which wasn‟t
removed by the limestone.
11. Production of steel
To make steel you are simply removing more impurities, such as,
manganese, silicon, etc.from the pig iron.
Impurities are removed by re-melting the metal and adding carbon,
steel scrap, and more limestone.
The metal can be melted using following methods.
Bessemer furnace
Open-hearth furnace
Electric process
L.D process( Linz- Donawitz Process)
Cementation process
Crucible steel process
Duplex process
12. Types of steel:
Steel
• Low carbon steel (mild steel)
• Medium carbon steel
• High carbon steel (tool steels)
• Cast iron
Alloy Steels
• Stainless steel
• High speed steel
13. Low Carbon Steel
Also known as mild steel
Contain 0.05% -0.32% carbon
Tough, ductile and malleable
Easily joined and welded
Poor resistance to corrosion
Often used a general purpose material like nails, screws, car bodies, etc
Structural Steel used in the construction industry
14. Medium Carbon Steel
Contains 0.35% - 0.5% of carbon
Offer more strength and hardness
less ductile and malleable
Structural steel, rails and garden tools
15. High Carbon Steel
Also known as „tool steel‟
Contain 0.55%-1.5% carbon
Very hard and Higher Strength
Less ductile and less malleable
Hand tools (chisels, punches)
Saw blades
16. Cast Iron
Contains 2%-4% of carbon
Very hard and brittle
Strong under compression
Suitable for casting [can be pour at a relatively low temperature]
Engine block, machine parts
17. Types of cast iron
White cast iron is named after its white surface when fractured, due to its
carbide impurities which allow cracks to pass straight through.
Grey cast iron is named after its grey fractured surface, which occurs
because the graphitic flakes deflect a passing crack and initiate countless
new cracks as the material breaks.
18. Alloys:Stainless Steel
Steel alloyed with chromium (18%), nickel (8%), magnesium (8%)
Hard and tough
Corrosion resistance
Comes in different grades
Sinks, cooking utensils, surgical instruments
19. Types of stainless steel:
Ferritic chromium:
• very formable, relatively weak;
• used in architectural trim, kitchen range hoods, jewelry, decorations,
utensils Grades 409, 430, and other 400
Austentitic nickel-chromium:
• non-magnetic, machinable, weldable, relatively weak; used in architectural
products, such as fascias, curtain walls, storefronts, doors & windows,
railings; chemical processing, food utensils, kitchen applications.
• series. Grades 301, 302, 303, 304, 316, and other 300 series.
20. Martensitic chromium:
• High strength, hardness, resistance to abrasion; used in turbine parts,
bearings, knives, cutlery and generally Magnetic. Grades 17-4, 410, 416, 420,
440 and other 400 series
Maraging (super alloys):
• High strength, highTemperature alloy used in structural applications,aircraft
components and are generally magnetic. Alloys containing around 18%
Nickel.
21. High Speed Steel
Medium Carbon steel alloyed withTungsten, chromium, vanadium
Very hard
Resistant to frictional heat even at high temperature
Machine cutting tools (lathe and milling)
Drills
22. Manufacture of steel :
Bessemer Process:
The most prominent present day steel making process.
The bessemer converter is wide at bottom and narrow at top
Mounted on two horizontal trunnions.
Tuyeres or nozzle provided at bottom to allow passage of air.
Open- hearth Process:
Also referred as Siemens- Martin process.
The steel produced is more homogenous than by Bessemer process.
23. BESSEMER PROCESS
Working of BESSEMER CONVERTER:
The converter is tilted and charged with molten pig-
iron.
The converter is brought in an upright position and
blast of hot air is forced inside.
The air passes through molten pig-iron, oxidizes
impurities and a reddish- yellow flame is formed at the
top.
Within 10-15 minutes ,all the impurities of pig-iron are
oxidized.
When intensity of flame reduces, the blast is shut off
and required amount of suitable material such as ferro-
manganese, spiege- leisen,etc. is added to make steel
desired quality.
24. OPEN -HEARTH PROCESS
The hearth is filled with molten pig-iron from
blast furnace.
Mixture of pre-heated air and coal gas
inserted in the furnace.
Mixture catches fire and because of peculiar
form of roof, it attacks molten metal
It produces intense heat and impurities are
oxidized.
Ferro-manganese, spiege-leisen,etc.is added
to make steel of required quality.
The molten metal is then poured into moulds
for forming ingots.
These ingots further treated to form steel of
commerical pattern.
25. Physical properties of steel
Factors affecting physical properties :
Carbon content:
The variation in carbon % produces steel of different grades
Presence of impurities:
The usual impurities in steel are silicon, sulphur, phosphorus and manganese
Silicon
• content less than 0.20% - no appreciable on the physical properties of steel
• Silicon content 0.30-0.40% - elasticity and strength are increased
Phosphorus
• detrimental effects on steel
• Phosphorus content should be below 0.12%
• It reduces shock resistance, ductility and strength
Manganese
• helps to improve strength of mild steel
• Content can be 0.30 – 1%
• If it exceeds about 1.5% or more , steel becomes brittle
26. Heat treatment process:
To enhance properties such as strength, ductility,hardness and toughness
To change the structure of steel
To increase the resistance to heat and corrosion
The principal processes involved in heat treatment of steel are as follows:
1) Annealing
2) Normalizing
3) Hardening
4) Tempering
5) Case hardening
6) Cementing
7) Cyaniding
27. Heat treatment process.
ANNEALING :
Annealing is the process whereby heat is introduced to mobilise the atoms and
relieve internal stress.
After annealing, it allows the metal to be further shaped
It involves the re-crystallization of the distorted structure
Process of Annealing:
The steel is heated at a desired temperature.
Temperature depends upon the carbon content of steel.
Holding the steel at the annealing heat till it is thoroughly
heated.
The time required for annealing depends upon the type of
furnace, nature of work, etc.
The steel is allowed to cool slowly in the furnace.
(referred table no. 11-2 from engineering materials; Rangwala book)
28. NORMALIZING:
The object of this process is to restore steel structure to normal condition.
It is adopted when the structure of steel is seriously disturbed due to any reasons.
This process makes the steel reasonably ductile without affecting its strength.
Process of Normalizing:
The steel is heated at 40 to 50 degree C above it critical temperature.
Maintained the steel at the same temperature for a short duration.
The steel is then allowed to cool down at room temperature.
Process also known as Air Quenching
HARDENING:
The steel is to be made hard by the process.
The process of hardening is just similar to annealing except that there is difference in rate of
cooling.
In hardening process, the cooling is to be carried out at controlled rate.
Such controlled rate of cooling is called as Quenching
Hardening is the process of increasing the hardness of steel by adding a high amount of
carbon
The degree of hardness depends on the amount of carbon present in steel and the form in
which it is trapped during quenching.
Once hardened, the steel is resistant to wear but is brittle and easily broken under load.
29. TEMPERING
The steel after being quenched in hardening process is reheated to suitable
temperature.
The temperature should be below critical temperature.
The temperature is maintained for a certain period.
The duration of period depends on quality of steel required and
composition of steels.
The steel is then allowed to cool.
The steel after hardening must be tempered to achieve the following objects:
1. To improve ductile, strength, toughness.
2. To increase the hardness and wear resistance.
3. To reduce brittleness
4. To relieve the internal stresses caused by hardening.
30. CASE HARDENING
Case hardening is a process used with mild steel to give a hard skin
The core of specimen remains tough and ductile and at the same time, becomes hard.
Such a result is achieved by increasing the carbon content at the surface.
The process is also known as a process of chemical heat treatment
In this process, the saturation of the surface having low carbon steel is carried out by
diffusion of carbon from the surrounding medium at a high temperature.
Process of Case Hardening:
The article which is to be carburized in held in the carburizing mixture from a definite
time at a definite temperature.
The time and temperature depends upon the depth of case required and composition of
steel.
The usual period is 6-8 hours and temperature range is 900- 950 degree C.
After carburizing, the article is treated in one f the following ways:
1. It is quenched directly from the box at carburizing temperature.
2. It is cooled slowly in the box and then it is reheated and quenched.
3. It is cooled slowly in the box and then it is reheated twice and quenched twice.
31. CEMENTING:
In this process, the skin of the steel is saturated with carbon.
The process consists in heating of the steel in a carbon rich medium between the
temperature of 880-950 degree C.
CYANIDING:
The process is used to produce hard cases on the surfaces of low or medium
carbon steels.
It consists in adding carbon and nitrogen to the surface layer of steel so as to
increase its hardness, wear resistance and fatigue limit.
The steel is heated in a molten cyanide salt bath maintained at a temperature of
950 degree C.
It is then followed by water or oil quenching.
32. ADVANTAGES AND DISADVANTAGES OF CYANIDING
ADVANTAGES:
It helps retaining the bright finish of parts.
Most suitable for parts subjected to high loads.
Cracks an distortions can be minimized by uniform heating maintained by the salt.
DISADVANTAGES:
Fumes formed during the process is unhealthy
There is risk of spiltering of poisonous salts.
33. NORMALIZING:
it consists in heating steel above critical range and cooling rapidly in air, but at rate
slower than the critical cooling rate.
The purpose of this heat treatment is to refine the grain structure resulting from
rolling, forging or other manufacturing process.
Process of Normalizing:
The steel is heated to a point 40-50 degree C above its upper critical temperature.
maintained at that temperature fro a short duration
Then allowed to cool down in still air at room temperature.
The process also know as Air Quenching.
34. The steel is widely used in electrical machinery, generators, transformers, etc.
For making suitable for such use, it`s magnetic properties are given very
importance.
Can be obtained by adjusting it`s chemical composition.
CARBON:
Carbon content as low as possible and should not exceed 0.10%
SILICON:
Presence of silicon increases of electrical losses and hence it is highly undesirable.
SULPHUR and PHOSPHORUS:
content of sulphur and phosphorus exceeds about 0.3%, the magnetic properties
of steel are greatly affected.
MANGANESE:
Content of manganese exceeds about 0.3% , it proves to be injurious to magnetic
properties of steel.
Magnetic properties of steel
35. Defects in steel:
Cavities or blow- holes: When gas is confined or imprisoned in
molten mass of metal.
Cold shortness: Due to presence of excess amount of phosphorus
Red shortness: Due to presence of excess amount of sulphur
Segregation: Some constituents of steel solidify at an early stage and
separate out from the main mass.
36. Market Forms Of Steel
Steel is used structurally in two ways
Reinforcement steel
Structural steel
37. Reinforcement steel
Concrete – weak in tension – strong in compression
Steel – strong in tension
Steel bars embedded in concrete – reinforcement
Develops good bond with concrete
38. Types of reinforcement bars
Mild steel and medium tensile steel / Plain steel bars
Round sections
Mild steel / medium tensile steel / plain steel bars
Plain steel bars – 5mm to 32mm
Designated as Fe250
Yield strength – 250 N/mm2
39. High yield strength deformed bars (HYSD)/TOR steel
Cold twisted deformed bars
Tor steel bars – longitudinal ribs in the form of continuous helix
Develop high bond strength due to interlocking with concrete
Mean diameters – 5mm to 40mm
Designated as Fe415, Fe500, Fe550
40. Structural steel sections
Rolled steel bar section:
• Indian Standard Round Bars (ISRO):
Designated as ISRO 10 (round bars having diameter 10mm)
Available in diameter varying from 5mm to 25mm.
Used as reinforcement in concrete structures , construction
of steel grillwork, etc.
41. Indian Standard square bars (ISSQ):
Designated as ISSQ 10 (10mm)
size vary from 5mm to 250mm
Used for grillwork, handrails for staircases, gates,windows, etc.
42. Rolled Steel Plate Section ( ISPL):
• Designated as ISPL 500 x 5 (500mm width and 5mm thickness)
• Available is different sizes with thickness varying from 5mm to 50mm
• Used for construction of water tanks and other storage
structures, built up beams, columns, base plate for foundations
etc.
43. Rolled Standard Sheet Sections (ISSH):
• Plates having thickness less than 5mm.
• Designated as ISSH 1800 x 600 x 4 (sheet having length 1800mm,
breadth 600mm and thickness 4mm).
• Used for construction of boxes and vehicle bodies.
44. Indian Standard Strips (ISST):
• Mainly used as beedings.
• Designated as ISST 100 x 2 (steel strip with a width of 100mm and
thickness 2mm).
45. Indian Standard Flats (ISF):
• Designated as ISF 10 x 3(flat of width 10mm and thickness 3 mm).
• Available in suitable widths varying from 10mm to 400mm
• Thickness varying from 3mm to 40mm.
• Used for steel grillwork for windows and gates.
46. Rolled SteelTubes:
• Inner diameter varying from 15 to 150mm.
• Thickness varying from 2 to 5.4mm.
• Efficient structural sections for formwork and trusses
47. Rolled Steel Angle Sections (ISA)
• Designated as ISA and width and length of legs
• Available as
Equal angle sections
i. Two legs will be equal in length
ii. Available in sizes varying from 20mm x 20mm x 3mm to 200mm
x 200mm x 25mm
Used in structural steelwork especially in the construction of
steel roof and filler joist floors.
48. Unequal angle sections
i. Two legs will be unequal in length.
ii. Available in sizes varying from 30mm x 20mm x3mm x 3mm to
200mm x 150 mm x 18mm
49. Bulb angle sections
• Extensively used in structural steel works like roof trusses, and as
connecting members for different structures.
50. Rolled steelTee sections:
• Resembles the alphabet T
• Consists of web and flange
• Designated by overall dimensions and thickness.
• Available in sizes varying from 20mm x 20mm x 3mm to 150mm x 150mm x
10mm.
• Widely used as members of the steel roof truss and form built – up
sections.
• Different types available are:
Indian Standard NormalTee (ISNT)
Indian Standard HeavyTee (ISHT)
Indian Standard ShortTee (ISHT)
Indian Standard JuniorTee (ISHT)
51. Rolled Steel Channel Sections:
• Consists of a web and two equal flanges.
• Designated by height of web and width of flange
• Available in sizes varying from 100mm x 45mm to 400mm x 100mm.
• Widely used for beams and columns.
• The different types available are:
Indian Standard Junior Channel (ISJC)
Indian Standard Light Channel (ISLC)
Indian Standard Medium Channels (ISMC)
52. Rolled Steel I – Sections
• Known as rolled steel joists or beams.
• Consists of two flanges connected by a web.
• Designated of overall depth and width of flange.
• Available in sizes varying from 75mm x 50mm to 600mm x210mm.
• Different types are:
Indian Standard junior beam (ISJB)
Indian Standard Light Beam (ISLB)
Indian Standard Medium Beam (ISMB)
Indian StandardWide Flange Beam (ISWB)
Indian Standard Heavy Beam (ISHB)
• Strongest and most economical of all sections
• Used as columns, purlins in trusses and grillage foundations.
53. Corrugated sheets:
• Formed by passing steel sheets through groves.
• Groves bend and press steels and corrugated are formed on the sheets
• Usually galvanized
• Also referred as galvanized iron sheets or G.I sheets
• Used for roof coverings.
54. Plain expanded metal
• Prepared from sheets of mild steel which are machine cut and drawn out
or expanded.
• Used for reinforcing concrete in foundations, roads, floors,
bridges,etc.
• It is also used for partition
55. Built –up sections:
• Composed of a combination of available basic sections like plates,
angles, channels etc.
• For increased strength and stability
• Different sections are joined by welding or riveting
Types of built – up sections
•Two angles back to back
•Two channels
•I-sections with top and bottom
plates
•Plate girder
•Built up column sections
