Stainlss steel AND CAST IRON

STEEL AND ITS ALLOYS
TUSHAR A ANYRAO
Asst. Professor, SVPCET, Nagpur

What is steel?
Steel is a interstitial solid solution of
iron and carbon containing 0.008 to
2% carbon by weight
Prof. Tushar A Aneyrao SVPCET, Nagpur

Classification of Steels
Steels are classified base on various
criterions:
Amount of carbon
Amount of alloying elements
Amount of deoxidation
Grain Coasening Characteristics
Method of Manufacturing
Depth of Hardening
Form and use

Amount of carbon
Low carbon steel
(0.008 – 0.3 %C)
Medium carbon steel
(0.3 – 0.6 %C)
High carbon steel
(0.6 – 2 %C)

Amount of carbon
Low carbon steel
Soft
ductile
malleable
tough
machinable
weldable
non hardenable by heat treatment

Applications of Low carbon steel
Good for cold working such as rolling into thin sheets
Good for fabrication work by welding, pressing or
machining
Used for wire, nails, rivets, screws, panels, welding rod,
ship plates, boiler plates, tubes for bicycles and
automobiles
Steels with o.15 to 0.3 %C are widely used as Structural
steels and used for building bars, grills, beams, angles,
channels etc.
Mild Steel is well known from this group

Medium carbon steel
Medium Soft
Medium ductile
Medium malleable
Medium tough
Depth of hardening is less
Slightly difficult to machine, weld and
harden
Difficult to cold work
They are also called as machinery
steels Prof. Tushar A Aneyrao SVPCET, Nagpur

Applications of medium carbon steel
Used for
Bolts
Axles
Lock washer
Forging dies
Springs
Wheel Spokes
Railway rails

High carbon steel
Hard
Wear Resistant
Brittle
Difficult to cold work
Very difficult to machine and weld
Depth of hardening is more
They are also called as Tool Steels

Applications of high carbon steel
Used for
Dies
Punches
Hammers
Chisels
Drills
Metal cutting saws
Razor blades

On the basis of alloying elements
Low alloy steels
(Total alloying elements are less than 10%)
High alloy steels
(Total alloying elements are more than 10%)

On the basis of alloying elements and
carbon content
Low carbon Low alloy steels
Low carbon High alloy steels
Medium carbon Low alloy steels
Medium carbon High alloy steels
High carbon Low alloy steels
High carbon High alloy steels

On the basis of deoxidation
Rimmed steels
Killed steels
Semi-killed steels

A molten steel contains large amount of dissolved
oxygen and other gases.
The solubility of gases is more in the liquid metal than
in the solid metal and hence the dissolved oxygen along
with other gases tries to go out as CO during
solidification and a large part of it gets entrapped into
solidified ingot.
Rimmed steels
In rimmed steels no treatment is given to dissolved
gases.
The tapped gases form blow holes which compensate
for the usual liquid to solid shrinkage.

Rimmed steels
The thin solidified layer of ingot i.e. rim (skin)
formed at surface which contains low carbon, less
impurities and no blow holes
These steels coarsen rapidly during heating in
austenitic region.
Generally low carbon steels containing less than
0.15% carbon are produced in sheet form in
rimmed condition and used for deep drawing and
forming operations.

Rimmed steels

Killed steels
The dissolved oxygen from the melt is completely
removed by addition of strong deoxidising agents
like Al, Si, Mn and V.
The deoxidisers are added to the steel in the
furnace prior to pouring into mould.
They rapidly combine with the dissolved oxygen
and form respective oxides thus reduces dissolve
oxygen.
Killed steel shows more shrinkage (called as pipe)
during solidification due to absence of blow holes.

Killed steels

Killed steels
Killed steels shows fined grain characteristics
since oxide inclusions which inhibits the grain
boundary migration
Killed steel ingot has sound , defect free, less
segregated structure throughout the cross section
Usually high carbon steels and alloy steels are
produced in the killed condition.

Semi-killed steels
In these steels part of the dissolved oxygen is
removed by addition of deoxidisers.
Blow holes formed compensate for part of the
shrinkage and hence pipe is less.
They show intermediate grain coarsening
characteristics.
Usually steels containing carbon between 0.15 to
0.25% are produced.

On the basis of Grain Coarsening
characteristics
During heating,100 % austenite is formed at just above
the upper critical temperature and the grains are of
smallest size. As the temperature increases above this,
the grain size may increase. Depending on the grain
coarsening characteristics, steels are classified into two
types as :
Coarse grained steels
Fine grained steels

characteristics
Coarse grained steels
Coarse grained steels coarsen rapidly with temperature.
Fine grained steels
These steels maintain a relatively fine and uniform grain size
even after holding for long time at high temperature. Fine
grained steels do not coarsen up to a definite temperature.
Above this temperature, they coarsen very fast and may
reach a size greater than those of coarse grained steels.

characteristics
Temperature
AusteniticGrainSize
700 800 900 1000 1100 1200
Coarse Grained Steels
Fined Grained Steels

characteristics
Usually rimmed steels behave coarse grained
steels.
Killed steels and alloy steels behave fine grained
steels.
The oxide inclusions in killed steels and
undissolved alloy carbides in alloy steels inhibit
the grain boundary migration, thus reducing grain
coarsening.
In the absence of such particles, grain
coarsening is rapid.

On the basis of Method of Manufacuring
Basic open hearth
Acid open hearth
Acid Bessemer
Basic oxygen process
Electrical Furnace

On the basis of Depth of Hardening
Non-hardenable
Can’t be hardened by quenching
Shallow hardening steels
hardened by quenching up to a small
depth
Deep hardening steels
hardened by quenching deeply

On the basis of Depth of Hardening
Non-hardenable
Very low hardenablilty
Low carbon steels with no alloying elements
Shallow hardening steels
Medium hardenability
Medium carbon steels with low alloying
elements
Deep hardening steels
High hardenability
High carbon steels with high alloying elements

On the basis of form and use
Based on form:
Cast steels
Wrought steels
Based on Use:
Boiler steels
Case hardening steels
Corrosion and heat resistant steels
Deep drawing steels
Electrical steels
Free Cutting steels
Machinery steels
Structural steels
Tool steels

ALLOY STEEL
 alloy steel are the steels containing other elements like ni,mn,cr,w,mo,v etc.
which are added to plain steels for enhancement of their one or more
properties.
 addition of such elements leads to……
1) more strength ,hardness and toughness at low and high temp.
2) better resistance to wear and abrasion due to the presence of allloy
carbides.
3) high hardenability
4) less tendency to warping and cracking during heat treatments.
5) more uniform properties throughout the cross-seection
1) less tendacy to decarburization

7) high corrosion and oxidation resistance
efeect of alloying elements
1)solid solution strengthening/hardening:
most of the alloying elements are soluble in ferrite to some extent and form
solid solution when added to steel.
solid solution are harder and stronger than pure metal and hence these
elements increases the strength ad hardness of steel.
example: mn, cr, w, mo, v, ti, si, al,zr,p,….
elements like p, si,mn and more
effective as solid soltion
strengtheners.

2) formation of carbides:
some of the alloying elements combine with carbon in the steel and form
respective carbides.
these alloy carbides are hard and increases wear and abrasion resistance of
steel.
chromium and vanadium carbides have maximum hardness and formation of
these carbides during tempering of high alloy tool steel.
example: ti,zr,v, nb,w, mo,cr,mn
3) formation of inclusions:
they may combine with oxygen and form oxides when added to steel.
example: si, al, mn, cr, v, ti,…..
4)shifting of critical temp and eutectoid carbon:
the alloying element may lower or raise thr transformation temp. of steel.

elements which are austenite stabilizer like ni and mn lower the eutectoid temp (a1) ,
while the elements which are ferrite stabilizers raise the above temp.
ti and mo are amongest the effective elements in the raising the eutectoid temp.

5)LOWERING CRITICAL COOLOING RATE:
MOST OF ALLOYING ELEMENTS (EXCEPT CO) SHIFT THE I.T. DIAGRAM TO THE RIGHT
SIDE, THUS DECREASING THE CRITICAL COOLING RATE .
THIS EFFECT IS VERY USEFUL FOR INCRESING THE HARDENABILITY OF STEEL.
ELEMENTS SUCH AS Mn, Mo, Cr AND Ni ARE MORE EFFECTIVE IN INCREASING THE
HARDENABILITY.

6) CHANGE IN VOLUME DURING TRANSFORMATION:
THE VOLUME CHANGE RESULTING FROM AUSTENITE TO MARTENSITE.
7) OTHER EFFECT:
CORROSION AND OXIDATION RESISTANCE MAY INCREASES
CREEP STRENGTH MAY INCREASED
FATIGUE STREGTH MAY ALSO GET INCREASED.

PROPERTIES AND USES OF ALLOYING ELEMENT:
1)SULPHAR
SULPHAR COMBINES WITH IRON AND FORMS IRON SULPHIDE WHICH IS A
HARD AND BRITTLE PHASE.
IT HAS LOW MELTING POINT
DURING HOT WORKING OF STEEL, THIS PHASE LIQUIFIES AT THE TEMP. OF
WORKING AND STEEL BECOMES HOT SHORT.
THESE PROBLEMS ARE REDUCED BY RESTRICTING THE AMOUNT OF SULPHAR
TO A MAXIMUM OF 0.05% AND ADDITION OF MANGANESE.
IN PRESENCE OF MANGANESE MnS IS FORMED WHICH IS NOT SO HARD AND
BRITTLE AS FeS.
ALSO ITS MELTING POINT IS HIGHER THAN THAT OF FeS , DUE TO THIS
MANGANESE ADDITION REDUCES BRITTLENESS AND HOT SHORTNESS.
IT ALSO INCREASES MACHINABILITY.

PROPERTIES AND USES OF ALLOYING ELEMENT:
2) PHOSPHORUS
PHOSPHOROUS DISSOLVES IN FERRITE PHASE AND INCREASES ITS TENSILE
STRENGTH AND HARDNESS.
IT IS MOST POWERFUL SOLID SOLUTION STRENGHTER.
ADDITON OF PHOSPOROUS IN LARGE AMOUNT INCREASES THE BRITTLENESS
IT ALSO INCREASES MACHINABILITY.
3)SILICON
IT DISSOLVES IN FERRITE ,INCREASES STRENGTH,HARDNESS,TOUGHNESS
WIYHOUT LOSS OF DUCTILITY.
SILICON IS ADDED UP TO 5% TO PRODUCE MAGNETICALLY SOFT MATERIALS
FOR TRANSFORMERS,MOTTORS AND GENERATOR LAMINATION.
SILICON IS PURPOSELY ADDED IN THE SPRING STEELS,CHISELS, PUNCHES AND
AUTOMOBILE VALVES TO INCREASE THEIR TOUGHNESS.
SILICON IS ADDDED UP TO 0.2% IN TOOL STEEL ,MORE THAN THIS % IT TEND
TO DECOMPOSE CARBIDE IN TO GRAPHITE.
4)MANGANESE
IT DISSOLVE IN FERRITE AND INCREASES YIELD STRENGTH ,TENSILE
STRENGTH, TOUGHNESS AND HARDNESS.Prof. Tushar A Aneyrao SVPCET, Nagpur

PROPERTIES AND USES OF ALLOYING ELEMENTS
SINCE IT IS LESS EXPENSIVE ELEMENTS,IT IS GENERALLY ADDED TO ALL
STRUCTURAL STEELS FOR STRENGTHENING PURPOSE.
HIGHER AMOUNT OF MANGANESE(12-14%) IS ADDED TO STEEL WITH 1 TO 2
% CARBON TO PRODUCE AN EXTREMELY TOUGH WEAR RESISTANT AND
NON MAGNETIC FIELD CALLED HADFIELD STEEL.
(MnS)IT INCREASES MACHINABILITY OF STEEL AND HENSE FREE CUTTING OR
FREE MACHINING STEEL CONTAIN Mn UP TO A MAXIMIUM OF 1.6% ALONG
WITH INCREASED AMOUNT OF SULPHAR.
5)NICKEL
IT DISSOLVES IN FERRITE AND INCRESES HARDNESS,TENSILE STRENGTH AND
TOUGHNESS WITHOUT DECREASING DUCTILITY.
UP TO 5% Ni IS ADDED TO STEELS REQUIRING HIGH TENSILE STRENGTH AND
TOUGHNESS.
HIGH ADDITION OF Ni MAKES THE STEEL AUSTENITIC AT ROOM TEMP. SUCH
STEELS ARE SOFT ,DUCTILE ,MALLEABLE AND NON MAGNETIC.
NICKEL ALSO INCREASES CORROSION RESISTANCE AND OXIDATION
RESISTANCE IF ADDED IN EXCESS OF 5%.
IT FOUND APPLICATION IN LOCOMOTIVE BOILERS,BOLTS,RAILWAY AXLE AND
BRIDGE STUCTURE.Prof. Tushar A Aneyrao SVPCET, Nagpur

PROPERTIES AND USES OF ALLOYING ELEMENTS
6) CHROMIUM
IT INCREASES HARDENABILITY OF STEEL TO A GREATER EXTENT .
IT FORMS CARBIDES AND INCREASES HARDNESS AND WEAR RESISTANCE OF
STEEL.
IT INCREASES CORROSION AND OXIDATION RESISTANCE WHEN ADDED IN
SUBSTANTIAL AMOUNT.
IT INCREASES SERVICE LIFE AND PERFOMANCE OF SUCH STEEL AS CUTTING
TOOLS,DIES,BALL BEARING.
7)TUNGUSTEN
IT INCREASES HARDENABILITY
IT FORMS CARBIDES AND INCREASES WEAR AND ABRASION RESISTANCE.
IT REDUCES THE TENDANCY OF DECARBURIZATION.
IT REFINE THE GRAIN SIZE.
8)MOLYBDENUM
SAME AS THAT OF TUNGUSTEN

PROPERTIES AND USE OF ALLOYING ELEMENT.
9)VANADIUM
IT INCREASES FATIGUE AND CREEP RESISTANCE.
THE RESISTANCE TO GRAIN COARSENING IS EXCELLENT.
EXCELLENT WEAR RESISTANCE.
10)COBALT
IT REDUCES HARDENABILITY OF STEEL.
IT IS AN IMPORTANT ALLOYING ADDITION IN PERMANENT MAGNETS, HIGH
TEMP. SERVICE MATERIAL.
11) ALLUMINIUM
IT IS A GRAIN REFINER
12)BORON
SMALL ADDITION OF BORON (0.001-0.003%)SHARPLY INCREASES
HARDENABILITY OF MEDIUM CARBON STEEL.
HIGH SURFACE HARDNESS,WEAR RESISTANCE,CORROSION RESISTANCE.
BORON DIFFUSED SURFACES OF HOT FORGING DIES CONSIDERABLY
INCREASES THEIR SERVICE LIFE.
IT IMPROOVER MACHINABILITY OF STEEL.

TOOL STEELS
THESE STEELS ARE SPECIALLY USED FOR WORKING,SHAPING AND CUTTING
OF METALS.
1)COLD WORK TOOL STEEL
2)HOT WORK TOOL STEEL
3)HIGH SPEED TOOL STEEL
4)SPECIAL PURPOSE TOOL STEEL.
ALL TOOL STEEL SHOULD BE HARD,TOUGH AND WEAR RESISTANT.
1)COLD WORK TOOL STEEL
THESE TOOL STEELS ARE USED FOR COLD WORKING OF METALS.
THEY HAVE GOOD HARDNESS AND WEAR RESISTANCE AT LOW TEMP.
SOME OF THE STEELS FROM THIS GROUP CONTAIN VERY LITTLE OR NO
ALLOYING ELEMENTS AND HENSE ARE LESS EXPENSIVE.
DEPENDING UPON THEIR HARDENING CHARACTERISTICS THEY ARE
CLASSIFIED IN TO SUBGROUPS SUCH AS WATER HARDENING STEELS (W-
SERIES), OIL HARDENING STEELS (O-SERIES), AIR HARDENING STEEL (A-
SERIES) AND HIGH CARBON HIGH CHROMIUM STEELS.(D-SERIES)

HOT WORK TOOL STEELS
THESE STEELS ARE MAINLY USED FOR HOT WORKING OF METALS SUCH AS
DRAWING,PIERCING,EXTRUDING ETC.
THEY HAVE GOOD STRENGTH,TOUGHNESS, HARDNESS AND WEAR
RESISTANCE.
THEY HAVE EXCELLENT RESISTANCE TO TEMPERING/SOFTENING .
THEY HAVE LOW TO HIGH ALLOY CONTENT WITH RELATIVELY LESS CARBON
(0.35 TO 0.65%)AND ARE CLASSIFIED IN TO THREE TYPES DEPENDING UPON
THE PRINCIPAL ALLOYING ELEMENT. THESE ARE CHROMIUM TYPE,
TUNGUSTEN TYPE,AND MOLYBDENUM TYPE.
HIGH SPEED TOOL STEEL
THESE STEELS MAINTAIN HIGH HARDNESS UP TO A TEMP OF ABOUT 550 C
AND HENCE CAN BE USED FOR CUTTING OF METALS AT HIGH SPEEDS.
THEY ALSO HAVE HIGH WEAR RESISTANCE AND CUTTING ABILITY.
HIGH SPEED STEELS ARE CLASSIFIED IN TO TWO TYPES……..
1)TUNGUSTEN HIGH SPEED: IT CONTAIN HIGH AMOUNT OF W WITH OTHER
ELEMENT SUCH AS Cr, V, AND Co.
THEY ARE DESIGNATED BY T-SERIES.

THE MOST WIDELY USED GRADE IS T1 WHICH CONTAIN 0.7%C,18 %W, 4%Cr
AND 1%V .
2)MOLYBDENUM STEELS :
A PART OF TUNGUSTEN FROM THE GROUP OF W-HIGH SPEED STEELS IS
SUBSTITUTED BY MOLYBDENUM AND HENSE THESE STEEL CONTAIN W,CR,V
AND CO IN THE ADDITION TO MO.
THIS SUBSTITUTION RESULTS IN LOWERING THE COST OF STEEL.
EVEN THOUGH MOLYBDENUM STEELS ARE CHEPER,THEY ARE DIFFICULT TO
HEAT TREAT BECAUSE OF MORE TENDENCY OF OXIDATION
DECARBURIZATION AND GRAIN GROWTH DURING HEAT TREATMENTS AS
COMPARED TO W-TYPE HIGH SPEED STEELS.
THIS TYPE IS DESIGNATED BY M-SERIES.
THE MOST WIDELY USED GRADE IS M2 WHICH CONTAIN 0.85%C, 6%W,
5%MO, 4%Cr, AND 2%V.
APPLICATION:
DRILLS ,LATHE TOOLS , PUNCHES, DRAWING DIES, AND WOOD WORKING
TOOS.
TAPS
REAMERS ,MILLING CUTTERS, SAW.

HIGH CARBON HIGH CHROMIUM STEEL(HCHC)
THEY HAVE HIGH HARDENABILITY AND HENSE CAN BE HARDENED BY OIL
OR AIR QUENCHING.
THEIR DISTORTION DURING HARDENING IS LESS.
THEY CONTAIN CARBON ABOVE 1.5% AND SOME OF GRADES CONTAIN
CARBON EVEN MORE THAN 2% WITH CHROMIUM ABOUT 12 % AND OTHER
ELEMENT SUCH AS W,MO, V IN SMALL AMOUNT.
DUE TO THIS ,THE AMOUNT OF COMPLEX ALLOY CARBIDE IS MORE WHICH
INCREASES HARDNESS AND WEAR RESISTANCE OF THESE STEELS,BUT THEY
DIFFICULT TO MACHINE.
THEY ARE USED FOR DRAWING DIES, BLANKING DIES, FORMING DIES,
COINING DIES, THREAD ROLLING DIES. TRIMMING DIES, BUSHINGS, SHEAR
BLADES, PUNCHES, COLD FORMING ROLLS,CUTTING TOOLS,GUAGES ETC.
THEY MAINTAIN SUFFICINT HARDNESS UP TO 500 C DUE TO PRESENCE OF
ALLOY CARBIDES.

OIL HARDNED NON SHRINKAGE STEEL(OHNS)
THESE STEEL CONTAIN SMALL AMOUNT OF ALLOYING ELEMENTS SUCH AS W,
Mn, Cr, Mo AND V.
DUE TO THIS ,THEIR HARDENABILITY IS BETTER THAN THE WATER
HARDENING TOOL STEELS AND THEREFORE ,THEY CAN BE HARDENED BY OIL
QUENCHING.
THEY ARE NOT EXPENSIVE AS OTHER TOOL STEEL AND ARE USED FOR
BLANKING AND FORMING DIES,SHEAR BLADE, MASTER TOOLS, CUTTING
TOOLS AND GUAGES.
THE DISTORTION DURING HARDENING IS LESS AND HENSE THEY ARE CALLED
AS OIL HARDENING NON-SHRINKAGE (OHNS) STEELS.
A CHEAPEST NON SHRINKAGE STEEL (O2) CONTAIN 0.9%C AND 1.6%Mn .
A BETTER STEEL CONTAINS 1% C, 0.95% Mn, 0.5%W, 0.75% Cr AND 0.2%V.

STAINLESS STEEL:
THESE STEEL HAVE HIGH CORROSION RESISTANCE AND HENSE THEY DO NOT
CORRODE IN MOST OF THE THE USUAL ENVIRONMENTAL CONDITIONS.
THE HIGH CORROSION RESISTANCE IS DUE TO THE PRESENCE OF CHROMIUM
IN THESE STEEL.
FOR SUFFICIENT CORROSION RESISTANCE TO HAVE STAINLESS PROPERTY IN
THE MOST GENERAL TYPE ENVIRONMENTAL CONDITIONS, THE MINIUM
AMOUNT OF CHROMIUM IN THE SOLID SOLUTION FORM SHOULD BE
GRETER THAN 13%.
AMOUNT OF CHROMIUM COMBINING WITH CARBON IS 17 TIMES THE
AMOUNT OF CARBON.
HIGHER THE CHROMIUM IN THE SOLID SOLUTION FORM AND LESSER THE
AMOUNT OF CARBIDES, MANY OTHER ELEMENTS SUCH AS Ni, Mn,Mo,Ti,Cb,
Ta, ETC. ARE ADDED TO IMPROVE CERTAIN PROPERTIES
VARIOUS TYPE OF STAINLESS STEEL HAVE ONE OR MORE OF THE FOLLOWING
PROPERTIES IN ADDITION TO THEIR HIGH CORROSION RESISTANCE.
HIGH DUCTILITY
HIGH RESISTANCE TO OXIDATION
GOOD WELDABILITY

STAINLESS STEEL:
GOOD CREEP RESISTANCE
EXCELLENT SURFACE FINISH AND APPEARANCE.
CLASSIFICATION OF STAINLESS STEEL
1)GROUP A
CHROMIUM IS LESS THAN 13%
HARD, WEAR RESISTANCE, MAGNETIC
APPLICATION: SPRING,BALL BEARINGS,VALVES,RAZORS AND RAZOR
BLADES,SURGICAL INSRUMENT, CUTTING TOOLS, CUTLERY ITEMS.
2)GROUP B
CHROMIUM IS MORE THAN 13%
OXIDATION RESISTANCE,SOFT,DUCTILE,MALLEABLE,MAGNETIC.
APPLICATION:VESSEL IN CHEMICAL AND FOOD INDUSTRIES, PRESSURE
VESSELS,FURNACE PART, HEATERS, HEAT EXCHANGERS, JUCE CARRYING PIPES
IN SUGAR INDUSTRIES, ARCHITECTURAL AND AUTOMOTIVE TRIM,
RESTAURANT EQUIPMENT , POTS AND PANS.

GROUP C
THIS GROUP INCLUDE THOSE ALLOY WHICH CONTAIN AT LEAST 24% OF THE
TOTAL OF Cr, Ni AND Mn.
THE AMOUNT OF Cr IN THESE ALLOYS IS AT LEAST 18% WITH CARBON
CONTENT BETWEEN 0.03 AND 0.25%
SOFT ,DUCTILE, MALLEABLE, NON MAGNETIC,LOW THERMAL CONDUCTIVITY.
APPLICATION:ENGINE MANIFOLDS,FOOD AND CHEMICAL PLANTS, TUBULAR
EXCHANGERS,UTENSILS,WRIST WATCHES, SANITARI FITTINGS ETC.

CAST IRON
CAST IRON BASICALLY THE ALLOYS OF IRON AND CARBON IN WHICH THE
CARBON VARIES BETWEEN 2 TO 6.67% I.E. MORE THAN THE SOLUBILITY
LIMIT OF CARBON IN AUSTENITE REGION AND LESS THAN THE CARBON
CONTENT OF CEMENTITE.

CAST IRON
COMMERCIAL CAST IRON ARE COMPLEX IN COMPOSITION AND CONTAIN
CARBON IN THE RANGE OF 2.3 TO 3.75 % WITH OTHER ELEMENTS SUCH AS
SILICON ,PHOSHORUS, SULPHAR AND MANGANESE IN SUBSTANSTIAL
AMOUNT.
BECAUSE OF THEIR POOR DUCTILITY AND MALLEABILITY, THEY CAN NOT BE
FORGED, ROLLED, DRAWN OR PRESSED IN TO THE DESIRED SHAPE; BUT ARE
FORMED BY MELTING AND CASTING WITH OR WITHOUT MACHINING TO THE
REQUIRED FINAL SHAPE AND SIZE AND HENCE THE NAME “CAST IRON”.
THEY ARE CHEAPEST AMONGEST THE COMMERCIAL ALLOYS.
THEY AARE EASIER TO MELT BECAUSE OF THEIR LOWER MELTING TEMP.
THEY HAVE EXCELLENT CASTABILITY
THEIR CORROSION RESISTANCE IS FAIRLY GOOD.
THEY ARE BRITTLE
HIGH HARDNESS TO WEAR AND ABRASION
EXCELLENT MACINABILITY.

CLASIFICATION OF CAST IRON
ON THE BASIS OF FURNACE USED IN THEIR MANFACTURER
1)CUPOLA CAST IRON
2)AIR FURNACE CAST IRON
3)ELECTRIC FURNACE CAST IRON
4)DUPLEX CAST IRON
ON THE BASIS OF COMPOSITION AND PURITY
1)LOW CARBON,LOW SILICON CAST IRONS
2)HIGH CARBON, LOW SULPHAR CAST IRONS
3)NICKEL ALLOY CAST IRON ETC
ON THE BASIS OF MICROSTRUCTURE AND APPEARANCE OF FRACTURE
1)WHITE CAST IRON
2)MALLEABLE CAST IRON
3)GREY CAST IRON
4)NODULAR CAST IRON
5)MOLTED CAST IRON
6)CHILLED CAST IRON
7)ALLOY CAST IRON

WHITE CAST IRON
IN THESE CAST IRON ,ALL THE CARBON IS PRESENT IN THE FORM OF
COMBINED CARBON(I.e. CEMENTITE) AND THERE IS NO FREE CARBON
(I.e. GRAPHITE).
THE APPEARANCE OF A FRACTURED SURFACE IS WHITE BECAUSE OF
ABSENCE OF GRAPHITE AND HENSE THE NAME IS “WHITE CAST IRON”.
COMPOSITION :
3.2TO 3.6%C , 0.4TO 1.1%Si, 0.1TO 0.4%Mg, LESS THAN 0.3%P, LESS THAN
0.2%S, REMAINING Fe.
PROPERTIES: VERY HARD, EXCELLENT ABRASIVE RESISTANCE ,DIFFICULT TO
MACHINE, HIGH TENSILE STRENGTH AND BRITTLE, LOW COMPRESSIVE
STRENGTH.
APPLICATION:
RIM OF CAR
RAILWAY BRAKE BLOCKS,PUMP IMPELLERS
SHOT BLASTING NOZZLES.
MILL LINERS,CRUSHER

MALLEABLE CAST IRONS
THESE CAST IRONS ARE PRODUCED WHITE CAST IRON CASTINGS BY A
MALLEABLIZING HEAT TREATMENT.
THE HEAT TREATMENT CONSISTS OF HEATING THE WHITE CASTINGS
SLOWLY TO A TEMPERATURE BETWEEN EUTECTOID AND EUTECTIC
TEMPERATURES USUALLY AT AROUND 900C (800-950 C) AND HOLDING AT
THIS TEMP. FOR LONG TIME (24 HOURS TO SEVERAL DAYS) FOLLOWED BY
COOLING TO ROOM TEMP.

GOOD DUCTILITY,TOUGHNESS AND ARE BENDABLE, LOW COEFFICIENT OF
THERMAL EXPANSION, MODERATE COST.
T.S.------------ 25 TO 70 KG/MM2
ELONGATION-------- 6 TO 18%
HARDNESS-----------80 TO 275 BHN
TYPES OF MALLEABLE CAST IRON
1)FERITIC MALLEABLE
2)PEARLITIC MALLEABLE
3)PEARLITIC-FERRITIC MALLEABLE
4)BLACK HEART MALLEABLE
5)WHITE HEART MALLEABLE.
2 TO 3 %C, 0.6 TO 1.3%Si, 0.2 TO 0.6% Mg, LESS THAN 0.15%P ,LESS THAN
0.10%S , REMAINING Fe.
APPLICATION:
RAIL ROAD, GEAR CASE, UNIVERSAL JOINT YOKE, AUTOMOTIVE CRANKSHAFT,
ELECTRICAL LINE HARDWARE, AGRICULTURAL IMPLEMENTS.

GRAY CAST IRON
THE CAST IRON CONTAINING GRAPHITE IN THE FORM OF FLAKES (WHORL
LIKE SHAPE SHOWN IN FIG.) ARE CALLED AS GRAY CAST IRON.
PROPERTIES:
EXCELLENT MACHINABILITY
GOOD COMPRESSIVE STRENGTH
GOOD BEARING PROPERTIES
FAIRLY GOOD CORROSION RESISTANCE.

C- 3.2TO 3.7 %
Si- 2 TO 3.5 %
S- 0.06 TO 0.1 %
P- 0.1 TO 0.2%
Mn- 0.5 TO1 %
APPLICATION
MACHIN BASES, ENGINE FRAMES, DRAINAGE PIPES, ELEVATORS AND
INDUSTRIAL FURNACE COUNTER WEIGTH, PUMP HOUSINGS, CYLINDERS AND
PISTON OF I.C. ENGINES, FLY WHEELS ETC.
NODULAR CAST IRON:
THESE CAST IRON CONTAIN GRAPHITE IN THE FORM OF NODULES OR
SPHEROIDS.
THESE ARE PRODUCED FROM GRAY CAST IRONS BY THE ADDITION OF SMALL
QUANTITY OF CERTAIN ELEMENT CALLED AS NODULIZING ELEMENTS SUCH
AS MAGNESIUM, CERIUM, CALCIUM, BARIUM,LITHIUM OR ZIRCONIUM.
THE MOST COMMON ADDITON TO GRAY CAST IRON FOR PRODUCTION OF
NODULAR CASTINGS IS MAGNESIUM.(0.06 TO 0.08%)

COMPOSITON
C- 3.2 TO 4.2%
Si- 1 TO 4%
MAGNESIUM – 0.1 TO 0.8%
Ni – 0.0 TO 3.5%
Mg – 0.5 TO 0.1%
REMAINING IRON
PROPERTIES
HIGH DUCTILITY
GOOD FATIGUE STRENGTH,WEAR RESISTANCE, SHOCK RESISTANCE
,EXCELLENT CASTABILITY,HIGH TOUGHNESS
APPLICATION
CRANKSHAFT, GEARS,PUNCH DIES, SHEET METAL DIES, METAL WORKING
ROLLS, FURNACE DOORS, PIPES, PISTON, CYLINDER BLOCKS AND HEADS, AND
BEARING BLOCKS.

Specification of Steels
Indian Standard Designation
System:
Indian standard code for designation of steel
was adopted by Indian standard Institution (ISI)
in 1961.
Indian specifications are based on
Mechanical Properties
Chemical Composition

Indian Standard Designation System:
Code designation on the basis of Mech
properties is based upon T.S. and Y.S.
Property Symbol
T.S. (N/mm2) Fe
T.S. (Kg/mm2) St
Y.S. (N/mm2) FeE
Y.S. (Kg/mm2) StE

e.g. Fe 410 K
killed steel with minimum t.s. of 410 N/mm2
St 42
steel with minimum t.s. of 42 kg/mm2.
Fe E 270
Steel with minimum y.s. of 270 N/mm2

Indian Standard Designation System:
Designation of steels on the basis of chemical
composition consists of numerical figure
indicating 100 times the average % of carbon
content.
e.g. C20
STEEL WITH AVERAGE CARBON % 0.2
Alphabets are prefixed to identify type of steels
of various class
Letters C or T is followed by figure indicating
10 times the average % of Mn content
e.g.25C5
Steel with average carbon of 0.25% and Mn of
0.5% Prof. Tushar A Aneyrao SVPCET, Nagpur

e.g. 80 T 11
Plain carbon tool steel with avg. 0.8% carbon
and 1.1% manganese.
Symbols S,Se,Te,Pb or P are used to indicate free
cutting steels followed by a figure indicating 100
times the percent content of the respective
element.

Alphabets are prefixed to identify type of steels
of various class:
Type of Steels Prefix Used
For plain carbon steels C
For high alloy steels X
For low alloy steels -
For Plain carbon tool
steels
T
For alloy tool steels XT
For Wrought steel S
For Cast steel CSProf. Tushar A Aneyrao SVPCET, Nagpur

Alloy steels are designated in the symbolic form on the
basis of their alloy content by first specifying the average
content of carbon, followed by the chemical symbols of
the significant elements in the descending order of of
percentage content
If the average alloy content is upto 1%, the index
number is expressed upto 2 decimal places underlined
by a bar
e.g. if the Cr content is between 0.5 and 0.8 %, it is
represented as Cr 65
If the alloy content is between 1 and 10% the index
number is rounded to the nearest whole number
e.g.if the Cr content varies between 1.20 and 1.60 it may
be represented either as Cr 1 or Cr 1 4

If two or more significant alloying elements have same
alloy content, the chemical symbols are grouped
together followed by alloy content
e.g. if a steel contains Ni between 0.90 and 1.30% and Cr
between 1.20 to 1.60% , both may be represented as Ni
cr 1.
If the alloy content is over 10% , the index number is
rounded to the nearest whole no.
e.g. if the Cr content is between 12 and 18%, it is
represented as Cr 15.

S.
N.
Steel Specification
1 Fe410K
2 St42
3 FeE270
4 C20
5 C40
6 25C5
7 80T11
8 15Ni13Cr1Mo12
9 35S18 Prof. Tushar A Aneyrao SVPCET, Nagpur

S.
N.
Steel Specification
11 T75W18Cr4V1
12 T105Cr1Mn60
13 T85W6Mo5Cr4V2
14 T35Cr5Mo1V30

AISI/SAE Designation System
American Iron and Steel Institute and Society of
Automotive Engineers, London have almost similar
method of designation of steel and is based on the
chemical composition of steel.
The method consists of designating the steel with four
or five numerical digits. The first digit from left indicates
the types of steels as follows:
Digit Types of Steels
1 Carbon Steels
2 Ni Steels
3 Ni-Cr Steel
4 Mo Steels
Digit Types of Steels
5 Cr Steels
6 Cr-V Steels
7 Tungsten Steels
8 Ni-Cr-Mo SteelsProf. Tushar A Aneyrao SVPCET, Nagpur

For simple alloys, the second digit indicates the approximate % of
the predominant alloying elements and for other it indicates
modification of the alloy in that group.
The last two or three digits divided by 100 usually the average %
carbon in the steel.
In addition to the numerals, AISI specification may include a letter
prefix to indicate the manufacturing process of that steel as below:
Letter Manufacturing Process
A Basic open hearth alloy
steel
B Acid bessemer carbon steel
C Basic open hearth carbon

Some Important AISI/SAE steel designation groups
S.
N.
Details of the steel AISI/SAE Group
1 Carbon Steels
(i)Plain carbon
(ii)Free Cutting Steel
(iii)Manganese Steel
1XXX
10XX
11XX , 12XX
13XX
2 Nickel Steels
(i)0.5% Ni
(ii)1.5% Ni
(iii)3.5%Ni
(iv)5%Ni
2XXX
20XX
21XX
23XX
25XX

S.
N.
3 Nickel-Chromium Steels 3XXX
4 Molybdenum steels
(i)Cr-Mo
(ii)Cr-Ni-Mo
(iii)Ni-Mo
4XXX
41XX
43XX
46XX

S.
N.
5 Chromium steels 5XXX
6 Chromium-Vanadium
steels
6XXX
7 Tungsten steels 7XXX
8 Ni-Cr-Mo steels 8XXX
9 Silicon steels 92XX

Steel Specification
AISI1035 Steel with 0.35%C
AISI4340 Mo steel with 0.4%C
AISI52100 Cr-steel with 1%C and
AISI2440 Steel with 4%Ni and
0.4%C
AISI9260 Steel with 2%Si and
0.6%C

British Specification
British system of designation of steels is known as En series.
The En number of a steel has no corelation with the composition
or mechanical properties of steels
The new British system, BS970, used the first three digits for the
content of alloying elements, followed by a letter significance of
that is as shown below:
The last two digits after this letter is meant for carbon content
S.
N.
Letter Significance
1 A Analysis
2 H Hardenability
3 M Mechanical properties

British Specification
British
Old
En
British New Indian
Standard
AISI/SAE
En6 080M41 C35Mn75 AISI1035
En24 817M40 40Ni2Cr1Mo28 AISI4340
En31 534A99 109Cr1Mn60 AISI5210
0
En42 070A72 C75 AISI1074
For more detail contact usProf. Tushar A Aneyrao SVPCET, Nagpur

Stainlss steel AND CAST IRON

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