MSM-5 Ferrous & Non Ferrous Alloy

1. Department of Mechanical & Manufacturing Engineering, MIT, Manipal 1 of 3
CHAPTER 5
Ferrous &Nonferrous-alloys
MATERIAL SCIENCE & METALLURGY

2. Department of Mechanical & Manufacturing Engineering, MIT, Manipal 2 of 3
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Ferrous-alloys: Composition, properties and
applications of alloy steels (plain carbon steels, stainless
steels, free machining steels, HSS and maraging steels,
cast irons-grey, white and malleable cast irons.
Non-ferrous alloys: Types and explanation of brasses,
bronzes and Al-Cu alloys.

3. • Generally, plain carbon steels are the steels containing
less than 1.65 per cent manganese, 0.60 per cent
copper and 0.60 per cent silicon and without addition
of any specified elements.
• These steels are widely employed for general engineering
applications and their production.
• When the alloying elements are added intentionally to
alter the property of plain carbon steels are known as
alloy steels.

4. • The properties of alloy steels depend on both carbon
and alloying elements. Nature and amount(s) of
alloying element(s) dictate the engineering behaviour of
alloy steels.
• Alloying elements not only minimize/eliminate the
limitations of plain carbon steels but also impart/improve
specific characteristics such as resistance against
corrosion and oxidation, and magnetic and electrical
properties.

5. Effect of alloying elements
• Change eutectoid temperature
• Change composition of eutectoid point
• Shrink or expand γ field
• Stabilise austenite
• Stabilise carbides
• Shift nose of ttt curve
• Cause surface hardening
• Cause precipitation hardening
• Affect phase transformations

6. Effect of alloying elements
• Improve hardenability - Alloy steels have high
hardenability.
• Effect on the Phase Stability - Binary Fe-Fe3C
stability is affected and the phase diagram is altered.
• Change shape of the TTT Diagram

7. EFFECTS OF ALLOYING ELEMENTS IN
STEELS
Alloying
element
General Effects Special Steels
Aluminium Strong deoxidizer, soluble in
ferrite, forms nitrides, refines
grain size.
1. Nitralloy steel.
Boron Enhances hardenability
remarkably
Steels with high
hardenability.
Chromium Stabilizes ferrite, forms hard
and stable carbide, raises
tensile strength, fatigue
strength, hardness, wear
resistance and hardenability;
makes steel stainless when
exceeds 12% in solution.
General purpose
structural steels.
Ball bearing steels
Spring Steels.
Hard magnetic steels.
Stainless Steels.

8. EFFECTS OF ALLOYING ELEMENTS IN
STEELS
Alloying element General Effects Special Steels
Cobalt Checks grain growth, retains
hardness and strength at elevated
temperatures, raises remanence,
coercive force and thermal
conductivity.
1. Hot work steels.
2. High speed steels.
3. High temperature
steels.
4. Permanent magnet
steels.
Copper Raises yield point and yield
strength to tensile strength ratio,
causes precipitation hardening
when exceeds 0.30%.
1. In many steels with
improved resistance
against atmospheric
corrosion.

9. EFFECTS OF ALLOYING ELEMENTS IN
STEELS
Alloying element General Effects Special Steels
Manganese Stabilizes carbides, increases strength,
hardness and hardenability; acts as
mild deoxidizer, eliminates evil effect of
sulphur, stabilizes sustenite when
present in large amount.
1. Up to 2% in many alloy
steels.
2. Modified austenitic
stainless steels.
3. Hadfield steels
Molybdenum Strong carbide former, imparts high
temperature strength, enhances
resistance to creep, minimizes temper
brittleness, increases resistance to
corrosion of high chromium steels and
austenitic stainless steels.
An important alloying
element in
1. Case hardening steels.
2. Hot work steels.
3. High speed steels.
4. Creep resistant steels.
5. Stainless steels.

10. EFFECTS OF ALLOYING ELEMENTS IN
STEELS
Alloying element General Effects Special Steels
Nickel Stabilizes austenite, acts as
graphitizer, raises hardenability,
impact strength at normal and low
temperatures, and high temperature
strength; improves resistance to
fatigue and corrosion
1. Case hardening steels.
2. Low temperature steels.
3. Stainless steels.
4. Nonmagnetic steels.
Niobium Forms stable carbide, enhances high
temperature strength and creep
resistance, stabilizes stainless steels.
1. Creep resistant steels.
2. Stainless steels.

11. EFFECTS OF ALLOYING ELEMENTS IN
STEELS
Alloying
element
General Effects Special Steels
Silicon Stabilizes and hardens ferrite,
promotes graphitization, potent
deoxidizer, enhances resistance
to scaling and corrosion.
1. Spring steels.
2. Transformer steels.
3. Scale resistant steels.
Titanium Forms hard and stable carbide,
stabilizes ferrite, refines grains,
raises creep strength stabilizes
stainless steels.
1. Creep resistant
steels.
2. Stainless steels.
3. Permanent magnet
steels.

12. EFFECTS OF ALLOYING ELEMENTS IN
STEELS
Alloying
element
General Effects Special Steels
Tungsten Forms carbides, raises strength and
hardness, decreases toughness,
prevents grain growth, resists
softening during tempering,
increases hot strength and wear
resistance at high temperatures,
enhances cutting power of tool.
1. Wear resistant steels.
2. Hot work steels.
3. High speed steels.
4. Hard magnetic steels.
5. High temperature
steels.
Vanadium Forms carbides and nitrides, refines
grains, stabilizes ferrite, increases
hardness, strength and cutting
power at elevated temperatures.
1. Wear resistant steels.
2. Hot work steels.
3. High speed steels.
4. High temperature

13. PLAIN CARBON STEELTYPES:
• Dead Steel: C% upto 0.025. Not very important. Used
as wires or ropes. Hardened only by cold working.
Subjected only to recrystallization annealing.
• Low carbon steel: C% traces to 0.25. Accounts 90% of
total plain carbon steel output. Good formability and
excellent weldability. Used as structural, cold heading,
free cutting, case hardening steel. Poor response to
heat treatment. Contains upto 70% proeutectoid ferrite
phase at room temp. Annealing and normalising
treatments may be given but no much alteration in
mechanical properties.

14. PLAIN CARBON STEELTYPES:
• Medium carbon steel: C% from 0.25 to 0.65. Good
response to heat treatment. Used as railway
couplings, flanges, hand tools, sockets, levers etc.
• High carbon steel: C% from 0.65 to 1.5. High strength
and hardness. Poor formability, machinability and
weldability. Spheroidising improves machinability. C%
from 0.65 to 1.0 used as spring steels. Fabricating
method is hot rolling and cold drawing. Used as saws,
cutting tools, chisels, piston rings etc.

15. STAINLESS STEELS
Ferrous alloys that contain at least 11% Cr with or
without Ni., providing extraordinary corrosion resistance.
Excellent Corrosion resistance - thin, stable chromium
oxide or Nickel oxide film.
Types:Martensitic Stainless Steels: Straight Cr steels
with 11.5 to 18% Cr. Magnetic, cold workable,
machinable, higher toughness Stainless steels.
Hardened by air cooling. Temperng temp. is 590 C,
higher temp. causes lower corrosion resistance due to
the precipitation of carbides and 410-510C causes
temper embrittlement. S addition enhances
machinability.
Appln.: Turbine blades, Machine parts, springs, surgical
instruments, ball bearings, heat exchangers.

16. STAINLESS STEELS
Ferritic Stainless Steels: Straight Cr steels with 19 to
27% Cr. Not hardenable but moderately hardened by
cold working. Magnetic, cold or hot worked. Exhibits
excellent corrosion resistance in annealed condition.
Appln.:Nitric acid tank, furnace parts, nozzle,
combustion chambers.

17. Austenitic Stainless Steels: Cr-Ni or Cr –Ni- Mn
stainless steels. Nonmagnetic and can not be
hardened by heat treatment. Excellent corrosion
resistance among stainless steel category. Can be
hardened by cold deformation.
Appln.: Chemical & food processing equipment,
screw machine parts, shafts, valves, nuclear energy
applns., photographic equipments.
Precipitation-Hardenable (PH) Stainless Steels: Si,
Mn, Mo, Cu, Al, P in addition to Cr & Ni. Small amount
of Ni improves stability of austenite. They are either
austenitic or martensitic variety.
STAINLESS STEELS

18. HIGH SPEED STEEL
Alloying elements: 20-40%. Including W, Mo, Cr, V,
Co(for Hot hardness, machinability), 0.7-1.5%C
Application: High speed cutting tools, milling cutters, dril
bits ,dies, reamers, lathe centers.
Popular grade: 18-4-1 HSS ( W, Cr, V with 0.7%C and
Co 5-12%) Co addition tool life increases 200-300%.
Carbides formed: MC,M2C,M6C, M7C3, M23C6
VC and V4C are powerful carbides and control grain
coarsening upto 1290 Deg. Cent.
Co dissolves in matrix to improve machinability and
thermal conductivity. Tool life may be improved by 200-
300%. Also increases melting point.

19. Department of Mechanical & Manufacturing Engineering, MIT, Manipal 19 of 3
•High alloy steels containing carbon as impurity
element <0.03%), 18-25 per cent nickel, 7 to 10 per
cent cobalt, 3 to 5 per cent molybdenum, up to 1.75
per cent titanium and up to 0.20 per cent aluminium.
•Also contain beryllium, niobium and tungsten in
small amounts. Presence of nickel in large amounts
is needed for the formation of soft and ductile iron-
nickel martensite.
•Soft, ductile and tough martensite ( HCP structure)
is strengthened by precipitation hardening.
MARAGING STEELS

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•Properly heat treated maraging steel has a
microstructure consisting of fine particle of
intermetallic compounds in a martensitic matrix.
•Good yield strength to ultimate tensile strength
ratio, weldability, formability, excellent fracture
toughness and resistance to hydrogen
embrittlement.
•Two grades: 18%Ni martensite & 20- 25%Ni
martensite
Appln. : Space application.
MARAGING STEELS

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FREE MACHINING STEEL
Free machining / Cutting steel:-
•Low carbon steel variety containing Mn, Pb, S, B etc. as
small addition.
•Addition of these elements improves machinability by
converting the continuous chips as periodically broken
type due to incorporation of brittleness.
•Lead present in the matrix acts as solid lubricant to
reduce friction.
•Tool life improves.

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CAST IRON
•Cast iron has higher carbon and silicon contents
than steel.
•Exhibits a carbon rich phase.
•Depending primarily in composition & cooling
rate, cast iron can solidify according to the
thermodynamically metastable Fe-Fe3C system or
the stable Fe-Graphite system.
Basic classification of cast iron
Gray iron , White cast iron, spheroidal (nodular)
graphite (SG), temper graphite (TG) & alloy cast
iron

23. (a) Carbon: Higher is the carbon, more is graphite
formed and lower the mechanical properties. It also
lowers the melting point.
(b) Silicon: Silicon is a strong graphitiser and
increases the fluidity. Controls the relative
proportions of combined carbon and free graphite.
Silicon content may vary between 1.0% to 3.5%.
Silicon shifts the graphite-eutectic line upwards.
(c) Sulphur and Manganese: Sulphur retards
graphitisation and increases the size of the flakes,
reduces fluidity and is often causes blow holes in
castings. Sulphur is kept low in amount of 0.06 to
0.12%. It is present either as FeS or MnS.
Effect of alloying elements C.I. :

24. FeS tends to promote cementite formation,
Mn is a mild carbide forming element. Manganese
formes MnS, retards primarily graphitisation.
(d) Phosphorus- Most cast iron contain
phosphorus between 0.1 to 0.3%.
Its amount more than 0.9%, then it forms iron
phosphide (Fe3P), which form a ternary eutectic
with cementite and austenite. The ternary
Eutectic is called steadite.
Steadite is brittle and has a melting point of
around 960 degree. This increase the fluidity also
helps in giving good castability.
Effect of alloying elements C.I. :

25. Hypo eutectic iron-carbon alloys and all the
carbon is present in the combined cementite form.
Composition:2.5 – 3.5% C, 0.4 – 1.5% Si, 0.4 – 0.6
% Mn, 0.1 – 0.4% P, 0.15% S, and balance Fe.
At room temperature white cast iron is mixture of
pearlite and proeutectoid cementite.
Because of extreme brittleness and lack of
machinability, white irons find limited engineering
applications.
WHITE CAST IRONS

26. Application: Liners of cement mixers, ball mills,
pumps, wearing plates. Parts of sand-slingers,
certain type of drawing dies, extrusion nozzles,
grinding balls. Most parts are sand-cast and don’t
require much machining, which can be done by
grinding. A large tonnage of white cast irons is
used as a starting material for the production of
malleable cast iron parts.
• Brake shoes • Shot blasting nozzles • Mill liners •
Crushers • Pump impellers and other abrasion
resistant parts.
WHITE CAST IRONS

27. Containing flakes of graphite embedded in ferrite matrix,
which show a gray-blackish coloured fracture due to
graphite.
Hypoeutectic cast irons, the total carbon content lies
between 2.4% to 3.8%. The amount of carbon does not
exceed 3.8%. Higher the carbon%, more the eutectic
liquid, which yields more graphite as flakes, resulting in
poor mechanical properties.
Carbon is kept at least 2.4%. So that cast iron has good
fluidity and castability.
Silicon is kept between1.4 % to 3.5%. It being a graphitiser
controls carbon precipitation and the rate of cooling.
GRAY CAST IRON

28. Composition : Carbon : 2.4—3.8%, Silicon : 1.2—
3.5% , Manganese : 0.5—1.0%, Sulphur : 0.06—
0.12%, Phosphorus : 0.1—0.9%.
Application: Railway – car wheels, crushing rolls,
stamp shoes & dies, sprockets.
MALLEABLE cast iron
Cementite (iron carbide) is metastable phase. There
is a tendency for cementite to decompose into iron
and carbon, but under normal conditions the
decomposition rate is neglegible. Fe3C 3Fe + C
is the key for the manufacture of malleable cast iron.
GRAY CAST IRON

29. In malleable iron combined carbon of white cast iron
converts into irregular nodules of temper carbon
(graphite) and ferrite.
Application of malleable iron:
Application of malleable iron: Axle & differential
housings, Automobile cam &crank shafts,
sprockets, chain links, linkages, small tools
(wrenches, hammers, clamps).
Composition:2.5 – 3.5% C, 0.4 – 1.5% Si, 0.4 – 0.6 %
Mn, 0.1 – 0.4% P, 0.15% S, and balance Fe.
Malleable iron

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Non Ferrous alloy:-
Copper:-
Classification of Copper alloy
• Brass (Alloy of Copper and Zinc) – 2 types
 Alpha Brass (Upto 36 Wt.% Zn) – 2 types
• Yellow brass (20-36Wt.% Zn)
• Red brass (5-20Wt.% Zn)
 Alpha plus beta brass (36 to 46% Zn)
• Bronze:- (Copper and Tin)
 Tin bronze
 Silicon bronze
 Aluminium bronze
Al-Cu alloys: Upto 5 Wt% Cu.

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COPPER ALLOYS
• Brasses and Bronzes are most commonly used alloys
of Cu.
• Brass is an alloy with Zn. Bronzes contain tin,
aluminum, silicon or beryllium.
• Other copper alloy families include copper-nickels and
nickel silvers. More than 400 copper-base alloys are
recognized.

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COPPER ALLOYS

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• Brass is the most common alloy of Cu with Zn
• Brass has higher ductility than copper or zinc.
• Easy to cast - Relatively low melting point and high
fluidity
• Properties can be tailored by varying Zn content.
• Some of the common brasses are yellow, naval and
cartridge.
• Brass is frequently used to make musical instruments
(good ductility and acoustic properties).
• Homogenising, recrystallisation annealing & stress
relieve allealing treatments are given.
COPPER ALLOYS - BRASS

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Bronze
• Copper alloys containing tin, lead, aluminum, silicon
and nickel are classified as bronzes.
• Cu-Sn Bronze is one of the earliest alloy to be
discovered.
• Cu ores invariably contain Sn. Stronger than brasses
with good corrosion and tensile properties; can be
cast, hot worked and cold worked.
• Wide range of applications: ancient Chinese cast
artifacts, skateboard ball bearings,
surgical and dental instruments.
Bronze bearing

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Al-Cu alloy
Duralumin: Al –Cu alloy with less than 5 wt% Cu
and trace additions of Mg, Zn, Ni, Si etc.
Age hardenable alloy. It is possible to improve
hardness and strength of the alloy by heat
treatment. Generally used in air craft and
automobile industries.

37. Department of Mechanical & Manufacturing Engineering, MIT, Manipal 39 of 3
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