Engg Metallurgy

8/3/2019 Engg Metallurgy

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ENGINEERING MATERIALS AND METALLURGY

UNIT I

PART A

1. What is meant by alloying elements?

It is a mixture of two or more metals or a metals and a non metals. The

element which is present in the largest proportion is called the base metal, and

other element present is called as alloying elements.

2. State Hume rotherys rules?

Size factor:

The atoms must be of similar size, with less than 15% difference in

atomic radius

Crystal structure:

The material must have the same crystal structure. Otherwise, there is

some point at which the transition occurs from one phase to a second phase

with different structure.

Valence:

The atoms must have the same valence. Other wise the valence

electrons difference encourages the formation of compounds rather then

solutions.

Electro negativity:

The atoms must have approximately the same electro negativity.

3. What is phase diagram?

It is graphical representations of what phase are present in a materials system

at various temperatures, pressures, and compositions. And the phase diagrams

are also known as equilibrium diagram or constitutional diagrams.


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4. What is meant by the term phase?

A phase may be a portion of matter which is homogeneous.

A phase is defined as any physically distinct, homogeneous, and

mechanically separable portion of a substance.

In laymans term, a phase requires a unique structure, uniform

composition, and well-defined boundaries or interfaces.

5. State Gibbs phase rule?

It is a simple equation that relates the number of phases presents (P) in a

system at equilibrium with the number of degrees of freedom (F), the number

of components (C),And the number of non-compositional variables.

Gibbs phase rule: F = C-P+2

6. What are the types of cooling curves?

Cooling curve for pure metal or compound

Cooling curve of a binary solution

Cooling curve of a binary eutectic system or a multiphase alloy.

7. What is cooling curves?

Cooling curves are obtained by plotting the measured temperature at

equal intervals during the cooling period of a melt to a solid.

The data obtained from these cooling curves are useful in constructing

the equilibrium.

8. What are the uses of phase rule?


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The phase rule predicts maximum number of phase presents in the alloy

under equilibrium conditions at any point of diagram.

If number of phases is known, one can determine the degrees of

freedom using the phase rule.

Thus the phase is useful to know whether the temperature or pressure or

both variables can be changed without changing the structure of the

alloy.

9. What are the types of equilibrium phase diagram?

A phase diagram can be defined as a point as a plot of the composition of the

phases as a function of temperature in any alloy system under equilibrium

conditions.

Phase diagram for complete solid solubility

Phase diagram for partial solid solubility

Phase diagrams containing three-phase reactions.

10.What are the solid phases in the phase diagram?

-Ferrite ():

This phase is an interstitial solid solution of carbon in the BCC iron

crystal lattice.

Austenite ():

The interstitial solid solution of carbon in iron is called austenite.

Cementite (FeC):

The intermetallic iron - carbon compound (FeC) is called as

cementite.

- Ferrite ():

The interstitial solid solution of carbon in iron is called ferrite.


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PART - B

11. What are cooling curve? How does the time-temperature cooling curve of an

alloy of eutectic composition differ from the pure metal?

12. Explain in detail about the types of equilibrium phase diagram?

13. Explain the micro-constituents of iron-carbon alloys?

14. Explain briefly about the iron-carbon carbide equilibrium diagram?

15. Explain the transformations which take place in the structure of cast- iron?

UNIT II

PART A

1. Define heat treatment process?

Heat treatment process may be defined as an operation or combination


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Of operation involving heating and cooling of a metal/alloy in the solid state

to obtain desirable properties.

2. What is the purpose of heat treatment process?

To relieve internal stress.

To improve machinability.

To improve hardness of the metal surface.

To increase resistance to wear, heat and corrosion.

3. Define principles of heat treatment?

The rate of cooling is the controlling factor in developing hard or soft

structure. Rapid cooling from the critical range results in hard structure,

whereas very slow cooling produces the soft structure.

4. What are the types of heat treatment processes?

The important heat treatment processes are

Annealing

Normalizing

Hardening

Tempering

Aus tempering

Mar tempering

Case hardening

5. What is meant by annealing?


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The term annealing refers to a heat treatment in which a material is exposed to

an elevated temperature for an extended time period and then slowly cooled.

6. What is meant by recrystallisation?

Recrystallisation is a process by which distorted grains of cold-worked metal

are replaced by new, strain-free grains during heating above a specific

minimum temperature.

7. What is meant by normalizing?

Normalizing is similar to full annealing, but cooling is established in

still air rather than in the furnace.

Full annealing is an expensive and time consuming process. When a

reasonably soft and ductile material is required and cost savings are

desired.

8. What is quenching?

Quenching refers accelerated cooling.

The cooling can be accomplished by contact with a quenching mediumwhich may be a gas, liquid or solid.

Most of the times, liquid quenching media is widely used to achieve

rapid cooling.

9. What is mar tempering?

Mar tempering, also known as mar quenching, is a interrupted cooling

procedure used for steels to minimize the stresses, distortion and cracking of

steels the may be develop during rapid quenching.

10.What is meant by carburizing process?


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Carburizing is the process in which carbon atoms are introduced onto

the surface of the low carbon steel to produce a hard case of surface,

while the interior or core remains soft.

Steels for carburizing should have carbon from 0.10 to 0.20%

PART - B

11. Compare the contrast the process of full annealing, process annealing, stress relief

annealing, recrystallisation annealing, and spheroidise annealing?

12.(a) Describe the normalizing process of heat treatment.

(b) Differentiate between normalizing and full annealing.

13.(a) Explain the process of mar tempering. Compare and contrast it with aus

tempering process?

(b) Differentiate between hardness and hardenability?

14. (a) What are TTT diagrams?

(b) How a TTT diagram is drawn?

(c) Draw neat sketch of the TTT diagram for eutectoid steel?

15. Write short notes on the following surface heat treatment operation:

A. Carburizing (b) Nitriding

B. Cyaniding, and (d) carbonitriding.


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UNIT III

PART A

1. What are metals?

Metals are elemental substance

Metals are composed of elements which readily give up electrons to

provide a metallic bond and electrical conductivity.


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2. What are steels?

Steels are alloys of iron and carbon. However, steels contain other

elements like silicon, manganese, sulphur, phosphorus, nickel, etc.

The alloying elements are either intentionally added or retained during

the refining process.

3. What are plain carbon steels?

Plain carbon steels are those in which carbon is the alloying element that

essentially controls the properties of the alloys, and in which the amount of

manganese cannot exceed 1.65% and the copper and silicon contents each

must be less than 0.6%

4. What are the applications of plain carbon steels?

Plain carbon steels are used for mass production products such as

automobiles and applicance.

They also find applications in the production of ball bearings, base

plates, housings, chutes, structural members, etc.

5. What are low carbon steels?

The low-carbon steels represent the largest tonnage of all the steels

produced.

The low-carbon steels are those steels that contain less than about

0.25% carbon

The low-carbon steels are also known as mild steels.

6. What are the applications of high carbon steels?


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Typical applications of plain high-carbon steels include cutting tools and dies,

knives, razors, hacksaw blades, springs, and high-strength wires, etc. these are

the application of high carbon steels.

7. What are stainless steels?

It is an alloy of iron, chromium, and other elements that resist corrosion from

many environments. Three classes of stainless steels,

Austenitic stainless steels,

Ferritic stainless steels and Martensitic stainless steels.

8. What are the properties of copper?

Copper possesses very high electrical conductivity. In fact is this

respect it is second only to silver.

It is also has very high thermal conductivity.

It exhibits excellent resistance to corrosion

It is very soft, ductile and malleable.

9. What are the types of aluminium alloys?

The alloys of aluminium may be subdivided into two groups as:

Heat treatable aluminium alloys, and

Non-heat treatable aluminium alloys.

10. What is precipitation hardening?

11. It is also known as age hardening. Is the most important method of

strengthening the physical properties of some of the non-ferrous alloys by

solid state reaction.


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PART - B

12. (a) Give the classification of steels.

(b) Describe the properties and typical applications of low-medium and high carbon steels.

13.(a) What are the main classifications of stainless steels?

(b) Discuss the different types of stainless steel, making reference to

approximate compositions, structures, heat treatments.

14. Write an engineering brief about the following steels:

(a) Tool steels, (b) HSLA steels, and (c) maraging steels

15. (a) Explain the principle characteristic of cast iron and explain the factor which

affects the structure of cast iron.

(b) Describe the structures if the main types of cast irons and account for their

continued use as engineering materials.

16.(a) What is meant by age hardening? Explain the process of precipitation

strengthening treatment.

(b) Explain the effects of ageing temperature and time on the properties of the

alloys.


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UNIT IV

PART A

1. What are polymers?

The term polymer is derived from two Greek words poly and mers.The term poly means many, and the term mer means parts of

units. Thus polymers are composed of a large number of repeating

units of small molecules called monomers.

2. What is polymerization and types of polymerization?

It is the process of forming a polymer by linking together of monomers.

Two polymerization mechanisms are

Addition polymerization, and

Condensation polymerization.

3. What is addition polymerization?


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It is also known as chain reaction polymerization is a process by which

two or more chemically similar monomers are polymerized to form

long chain molecules is called as addition polymerization.

4. What is plastic?

It is defined as the organic polymer, which cab be moulded into any

desired shapes and size with the help of heat, pressure, or both

thermoplastics and thermosetting plastics.

5. What are thermoplastics?

It is known as thermoplasts, are the plastics whose plasticity increaseswith the increase in temperature. Thermoplasts can be repeatedly

moulded and remoulded to the desired shape and hence they have a

good rescale and scrap value.

6. What are thermosetting plastics?

It is also known as thermosets, are plastics which becomes permanently

hard when heat is applied and do not soften upon subsequent heating.

They cannot be remoulded or reshaped again and again

7. What are ceramics?

It is a non-metallic and inorganic solid that are processed and or used at

high temperature. Typical ceramics are electrical and thermal insulators

with good chemical stability and good strength in compression.

8. What are engineering ceramics?

Engineering ceramics, are also known as technical/ industrial ceramics

or advanced ceramics, are those ceramics that are specially used for


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engineering application or in industries. It is mainly oxides, carbides,

sulphides, and nitrides of metals.

9. What are the three stages in addition polymerization?

The addition polymerization occurs in three stages:

Initiation,

Propagation, and

Termination

10.What are phenolics?

It is also known as Bakelite, are the oldest family of thermosetting

plastics. The most important phenolic materials are the

polyformaldehydes.

PART - B

11.What do you understand by polymerization? With the help of suitable

examples, compare and contrast the process of addition polymerization andcondensation polymerization.

12. Define monomer and polymer. Write typical polymeric repeat unit structure

for both addition and condensation polymerization.

13.(a) Describe the difference between thermoplastics and thermosetting plastics.

(b) Explain the difference between commodity plastics and engineering

plastics.

14. List the properties and typical applications of the following thermoplastics:

(a) PTFE (b) PMMA (c) PET, and (d) PEEK

15.(a) What are ceramics? List and briefly explain five important properties of

ceramics that makes them useful engineering materials.


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(b) What are the main classifications of ceramics materials?

UNIT V

PART A

1. What is meant by mechanical properties of material?

Mechanical properties are those characteristics of material that describe

its behavior under the action of external force is known as mechanical

properties of material.

2. Define the term elasticity and plasticity?

Elasticity: It is the property of a material by virtue of which it is able to

retain its original shape and size after the removal of the load.

Plasticity: It is the property of a material by virtue of which permanent

deformation takes place, whenever it is subjected to the action of

external force.

3. What are the factor affecting mechanical properties?

The numbers of factor affect mechanical properties, the following

factors are:

Grain size

Heat treatment

Atmospheric exposure

Low and high temperature

4. What are the effects of heat treatment?

Since the heat treatment changes are refines the grain size,

therefore the mechanical properties are affected.


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It is also improve the workability, forge ability and machinability

of the metals.

5. What are thermoplastics?

It is known as thermoplasts, are the plastics whose plasticity increases

with the increase in temperature. Thermoplasts can be repeatedly

moulded and remoulded to the desired shape and hence they have a

good rescale and scrap value.

6. What are thermosetting plastics?

It is also known as thermosets, are plastics which becomes permanently

hard when heat is applied and do not soften upon subsequent heating.

They cannot be remoulded or reshaped again and again

7. What are ceramics?

It is a non-metallic and inorganic solid that are processed and or used athigh temperature. Typical ceramics are electrical and thermal insulators

with good chemical stability and good strength in compression.

8. What are engineering ceramics?

Engineering ceramics, are also known as technical/ industrial ceramics

or advanced ceramics, are those ceramics that are specially used for

engineering application or in industries. It is mainly oxides, carbides,

sulphides, and nitrides of metals.

9. What are the three stages in addition polymerization?

The addition polymerization occurs in three stages:


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Initiation,

Propagation, and

Termination

10.What are phenolics?

It is also known as Bakelite, are the oldest family of thermosetting

plastics. The most important phenolic materials are the

polyformaldehydes.

PART - B

11. Explain the two modes ofPlasticdeformation.Decribe the working of universaltesting machine with suitable diagram.

12. With help of a neat sketch explain the charpyimpact testing procedure and why impact specimens

are notched.

13. With help of a neat sketch explain the Izod impact

testing procedure and why impact specimens are

notched.


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Engg Metallurgy

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