The goal of heat treatment of steel is very often to attain a satisfactory hardness. The important microstructural phase is then normally martensite, which is the hardest constituent in low-alloy steels. The hardness of martensite is primarily dependent on its carbon content as is shown in Fig. 13.
If the microstructure is not fully martensitic, its hardness is lower. In practical heat treatment, it is important to achieve full hardness to a certain minimum depth after cooling, that is, to obtain a fully martensitic microstructure to a certain minimum depth, which also represents a critical cooling rate. If a given steel does not permit a martensitic structure to beformed to this depth, one has to choose another steel with a higher hardenability (the possibility of increasing the cooling rate at the minimum depth will be discussed later).
There are various ways to characterize the hardenability of a steel. Certain aspects of this will be discussed in the following article in the Section and has also been described in detail in previous ASM Handbooks, formerly Metals Handbooks (Ref 23). The CCT diagram can serve this purpose if one knows the cooling rate at the minimum depth. The CCT diagrams constructedaccording to Atkinsor Thelning presented above are particularly suitable.
Wednesday, 5 June 2013
CCT Diagrams
As for heating diagrams, it is important to clearly state what type of cooling curve the transformation diagram was derived from. Use of a constant cooling rate is very common in experimental practice. However, this regime rarely occurs in a practical situation. One can also find curves for so-called natural cooling rates according to Newton's law of cooling.
These curves simulate the behavior in the interior of a large part such as the cooling rate of a Jominy bar at some distance from the quenched end. Close to the surface the characteristics of the cooling rate can be very complex as will be described below. In the lower part of Fig. 9 is shown a CCT diagram (fully drawn lines) for 4130 steel. Ferrite, pearlite, and bainite regions are indicated as well as the Ms temperature. Note that theMs temperature is not constant when martensite formation is preceded by bainite formation, but typically decreases with longer times.
The effect of different cooling curves is shown in Fig. 10. Each CCT diagram contains a family of curves representing the cooling rates at different depths of a cylinder with a 300 mm (12 in.) diameter. The slowest cooling rate represents the center of the cylinder. As shown in Fig. 10, the rate of cooling and the position of the CCT curves depend on the cooling medium (water produced the highest cooling rate followed by oil and air, respectively). The more severe the cooling medium, the longer the times to which the C-shaped curves are shifted. The Ms temperature is unaffected.
These curves simulate the behavior in the interior of a large part such as the cooling rate of a Jominy bar at some distance from the quenched end. Close to the surface the characteristics of the cooling rate can be very complex as will be described below. In the lower part of Fig. 9 is shown a CCT diagram (fully drawn lines) for 4130 steel. Ferrite, pearlite, and bainite regions are indicated as well as the Ms temperature. Note that theMs temperature is not constant when martensite formation is preceded by bainite formation, but typically decreases with longer times.
The effect of different cooling curves is shown in Fig. 10. Each CCT diagram contains a family of curves representing the cooling rates at different depths of a cylinder with a 300 mm (12 in.) diameter. The slowest cooling rate represents the center of the cylinder. As shown in Fig. 10, the rate of cooling and the position of the CCT curves depend on the cooling medium (water produced the highest cooling rate followed by oil and air, respectively). The more severe the cooling medium, the longer the times to which the C-shaped curves are shifted. The Ms temperature is unaffected.
Decomposition of Austenite
The procedure starts at a high temperature, normally in the austenitic range after holding there long enough to obtain homogeneous austenite without undissolved carbides, followed by rapid cooling to
the desired hold temperature (Fig. 5). An example of an IT diagram is given in Fig. 6.
The cooling was started from 850 °C (1560 °F). TheA1 andA3 temperatures are indicated as well as the hardness. AboveA3 no transformation can occur. BetweenA1 andA3 only ferrite can form from austenite. In Fig. 6, a series of isovolume fraction curves are shown; normally only the 1% and 99% curves are reproduced. Notice that the curves are C-shaped.
This is typical for transformation curves. A higher-temperature set of C-shaped curves shows the transformation to pearlite and a lowertemperature set indicates the transformation to bainite. In between is found a so-called austenite bay, common for certain low-alloy steelscontaining appreciable amountsof carbide-forming alloying elements such aschromium or molybdenum.
the desired hold temperature (Fig. 5). An example of an IT diagram is given in Fig. 6.
The cooling was started from 850 °C (1560 °F). TheA1 andA3 temperatures are indicated as well as the hardness. AboveA3 no transformation can occur. BetweenA1 andA3 only ferrite can form from austenite. In Fig. 6, a series of isovolume fraction curves are shown; normally only the 1% and 99% curves are reproduced. Notice that the curves are C-shaped.
This is typical for transformation curves. A higher-temperature set of C-shaped curves shows the transformation to pearlite and a lowertemperature set indicates the transformation to bainite. In between is found a so-called austenite bay, common for certain low-alloy steelscontaining appreciable amountsof carbide-forming alloying elements such aschromium or molybdenum.
Formation of Austenite
During the formation of austenite from an original microstructure of ferrite and pearlite or tempered martensite, the volume (and hence the length) decreases with the formation of the dense austenite
phase (see Fig. 3). From the elongation curves, the start and finish times for austenite formation, usually defined as 1% and 99% transformation, respectively, can be derived. These times are then conveniently plotted on a temperature-log time diagram (Fig. 4).
Also plotted in this diagram are the Ac1 and Ac3 temperatures. Below Ac1 no austenite can form, and between Ac1 and Ac3 the end product is a mixture of ferrite and austenite. Notice that a considerable overheating is required to complete the transformation in a short time. The original microstructure also plays a great role. A finely distributed structure like tempered martensite is more rapidly transformed to austenite than, for instance, a ferriticpearlitic structure. This is particularly true for alloyed steels with carbide-forming alloying elements such as chromium and molybdenum. It is important that the heating rate to the hold temperature be very high if a true isothermal diagram is to be obtained.
phase (see Fig. 3). From the elongation curves, the start and finish times for austenite formation, usually defined as 1% and 99% transformation, respectively, can be derived. These times are then conveniently plotted on a temperature-log time diagram (Fig. 4).
Also plotted in this diagram are the Ac1 and Ac3 temperatures. Below Ac1 no austenite can form, and between Ac1 and Ac3 the end product is a mixture of ferrite and austenite. Notice that a considerable overheating is required to complete the transformation in a short time. The original microstructure also plays a great role. A finely distributed structure like tempered martensite is more rapidly transformed to austenite than, for instance, a ferriticpearlitic structure. This is particularly true for alloyed steels with carbide-forming alloying elements such as chromium and molybdenum. It is important that the heating rate to the hold temperature be very high if a true isothermal diagram is to be obtained.
Isothermal Transformation Diagrams
This type of diagram shows what happens when a steel is held at a constant temperature for a prolonged period. The development of the microstructure with time can be followed by holding small specimens in a lead or salt bath and quenching them one at a time after increasing holding times and measuring the amount of phases formed in the microstructure with the aid of a microscope. An alternative method involves using a single specimen and a dilatometer which records the elongation of the specimen as a function of time. The basis for the dilatometer method is that the microconstituents undergo different volumetric changes (Table 3). A thorough description of the dilatometric method can.
Transformation Diagrams
The kinetic aspects of phase transformations are as important as the equilibrium diagrams for the heat treatment of steels.
The metastable phase martensite and the morphologically metastable microconstituent bainite, which are of extreme
importance to the properties of steels, can generally form with comparatively rapid cooling to ambient temperature, that
is, when the diffusion of carbon and alloying elements is suppressed or limited to a very short range. Bainite is a eutectoid
decomposition that isa mixture offerrite and cementite. Martensite,the hardestconstituent, formsduring severe quenches
from supersaturated austenite by a shear transformation. Its hardness increases monotonically with carbon content up to
about 0.7 wt%. If these unstable metastable products are subsequently heated to a moderately elevated temperature, they
decompose to more stable distributions of ferrite and carbide. The reheating process is sometimes known as tempering or
annealing.
The transformation of an ambient temperature structure like ferrite-pearlite or tempered martensite to the elevatedtemperature structure of austeniteor austenite + carbideisalso of importance in the heat treatment of steel.
One can conveniently describe what is happening during transformation with transformation diagrams. Four different
typesof such diagramscan be distinguished. These include:
· Isothermal transformation diagrams describing the formation of austenite, which will be referred to as
ITh diagrams
· Isothermal transformation (IT) diagrams, also referred to as time-temperature-transformation (TTT)
diagrams, describingthe decompositionof austenite
· Continuous heatingtransformation (CHT) diagrams
· Continuous cooling transformation (CCT) diagrams
The metastable phase martensite and the morphologically metastable microconstituent bainite, which are of extreme
importance to the properties of steels, can generally form with comparatively rapid cooling to ambient temperature, that
is, when the diffusion of carbon and alloying elements is suppressed or limited to a very short range. Bainite is a eutectoid
decomposition that isa mixture offerrite and cementite. Martensite,the hardestconstituent, formsduring severe quenches
from supersaturated austenite by a shear transformation. Its hardness increases monotonically with carbon content up to
about 0.7 wt%. If these unstable metastable products are subsequently heated to a moderately elevated temperature, they
decompose to more stable distributions of ferrite and carbide. The reheating process is sometimes known as tempering or
annealing.
The transformation of an ambient temperature structure like ferrite-pearlite or tempered martensite to the elevatedtemperature structure of austeniteor austenite + carbideisalso of importance in the heat treatment of steel.
One can conveniently describe what is happening during transformation with transformation diagrams. Four different
typesof such diagramscan be distinguished. These include:
· Isothermal transformation diagrams describing the formation of austenite, which will be referred to as
ITh diagrams
· Isothermal transformation (IT) diagrams, also referred to as time-temperature-transformation (TTT)
diagrams, describingthe decompositionof austenite
· Continuous heatingtransformation (CHT) diagrams
· Continuous cooling transformation (CCT) diagrams
TheFe-CPhaseDiagram 2
The Fe-C diagram in Fig. 1 is of experimental origin. The knowledge of the thermodynamic principles and modern
thermodynamic data now permits very accurate calculations of this diagram (Ref 4). This is particularly useful when
phase boundaries must be extrapolated and at low temperatures where the experimental equilibria are extremely slow to
develop.
If alloying elements are added to the iron-carbon alloy (steel), the position of theA1,A3, andAcm boundaries and the
eutectoid composition are changed. Classical diagrams introduced by Bain (Ref 5) show the variation ofA1 and the
eutectoid carbon content with increasing amount of a selected number of alloying elements (Fig. 2). It suffices here to
mention that (1) all important alloying elements decrease the eutectoid carbon content, (2) the austenite-stabilizing
elements manganese and nickel decreaseA1, and (3) the ferrite-stabilizing elements chromium, silicon, molybdenum, and
tungsten increaseA1. These classifications relate directly to the synergisms in quench hardening as described in the
articles "Quantitative Prediction of Transformation Hardening in Steels" and "Quenching of Steel"in this Volume.
Modern thermodynamic calculations allow accurate determinations of these shifts that affect the driving force for phase
transformation (see below). These methods also permit calculation of complete ternary and higher-order phase diagrams
including alloy carbides(Ref 6). Reference should be made to the Calphad computer system (Ref7).
thermodynamic data now permits very accurate calculations of this diagram (Ref 4). This is particularly useful when
phase boundaries must be extrapolated and at low temperatures where the experimental equilibria are extremely slow to
develop.
If alloying elements are added to the iron-carbon alloy (steel), the position of theA1,A3, andAcm boundaries and the
eutectoid composition are changed. Classical diagrams introduced by Bain (Ref 5) show the variation ofA1 and the
eutectoid carbon content with increasing amount of a selected number of alloying elements (Fig. 2). It suffices here to
mention that (1) all important alloying elements decrease the eutectoid carbon content, (2) the austenite-stabilizing
elements manganese and nickel decreaseA1, and (3) the ferrite-stabilizing elements chromium, silicon, molybdenum, and
tungsten increaseA1. These classifications relate directly to the synergisms in quench hardening as described in the
articles "Quantitative Prediction of Transformation Hardening in Steels" and "Quenching of Steel"in this Volume.
Modern thermodynamic calculations allow accurate determinations of these shifts that affect the driving force for phase
transformation (see below). These methods also permit calculation of complete ternary and higher-order phase diagrams
including alloy carbides(Ref 6). Reference should be made to the Calphad computer system (Ref7).
The Fe-C PhaseDiagram
The basis for the understanding of the heat treatment of steels is the Fe-C phase diagram Because it is well
explained in earlier volumes of ASM Handbook, formerly Metals Handbook (Ref 1, 2, 3), and in many elementary
textbooks, it will be treated very briefly here. Figure 1 actually shows two diagrams; the stable iron-graphite diagram
(dashed lines) and the metastable Fe-Fe3C diagram. The stable condition usually takes a very long time to develop,
especially in the low-temperature and low-carbon range, and therefore the metastable diagram is of more interest. The FeC diagram showswhich phases are to be expected at equilibrium (or metastable equilibrium) for different combinationsof
carbon concentration and temperature. Table 1 provides a summary of important metallurgical phases and
microconstituents. We distinguish at the low-carbon end ferrite(α-iron), which can at most dissolve 0.028 wt% C at 727
°C (1341 °F) and austenite(γ-iron), which can dissolve 2.11 wt% C at 1148 °C (2098 °F). At the carbon-rich side we find
cementite (Fe3C). Of less interest, except for highly alloyed steels, is the δ-ferrite existing at the highest temperatures.
Between the single-phase fields are found regions with mixtures of two phases, such as ferrite + cementite, austenite +
cementite, and ferrite + austenite. At the highest temperatures, the liquid phase field can be found and below this are the
two phase fields liquid + austenite, liquid + cementite, and liquid + δ-ferrite. In heat treating of steels, the liquid phase is
always avoided. Some important boundaries at single-phase fields have been given special names that facilitate the
discussion. These include:
· A1, theso-called eutectoid temperature, which is the minimumtemperature for austenite
· A3
, the lower-temperature boundary of the austenite region at low carbon contents, that is, the γ/γ + α
boundary
· Acm, the counterpartboundaryfor high carbon contents, that is, the γ/γ + Fe3C boundary
Sometimes the letters c, e, or r are included. Relevant definitions of terms associated with phase transformations of steels
can be found in Table 2 as well as the Glossary of Terms in this Volume and Ref 3. The carbon content at which the
minimum austenite temperature is attained is called the eutectoid carbon content (0.77 wt% C). The ferrite-cementite
phase mixture of this composition formed during cooling has a characteristic appearance and is called pearlite and can be
treated as a microstructural entity or microconstituent. It is an aggregate of alternating ferrite and cementite lamellae that
degenerates ("spheroidizes" or "coarsens") into cementite particles dispersed with a ferrite matrix after extended hold
explained in earlier volumes of ASM Handbook, formerly Metals Handbook (Ref 1, 2, 3), and in many elementary
textbooks, it will be treated very briefly here. Figure 1 actually shows two diagrams; the stable iron-graphite diagram
(dashed lines) and the metastable Fe-Fe3C diagram. The stable condition usually takes a very long time to develop,
especially in the low-temperature and low-carbon range, and therefore the metastable diagram is of more interest. The FeC diagram showswhich phases are to be expected at equilibrium (or metastable equilibrium) for different combinationsof
carbon concentration and temperature. Table 1 provides a summary of important metallurgical phases and
microconstituents. We distinguish at the low-carbon end ferrite(α-iron), which can at most dissolve 0.028 wt% C at 727
°C (1341 °F) and austenite(γ-iron), which can dissolve 2.11 wt% C at 1148 °C (2098 °F). At the carbon-rich side we find
cementite (Fe3C). Of less interest, except for highly alloyed steels, is the δ-ferrite existing at the highest temperatures.
Between the single-phase fields are found regions with mixtures of two phases, such as ferrite + cementite, austenite +
cementite, and ferrite + austenite. At the highest temperatures, the liquid phase field can be found and below this are the
two phase fields liquid + austenite, liquid + cementite, and liquid + δ-ferrite. In heat treating of steels, the liquid phase is
always avoided. Some important boundaries at single-phase fields have been given special names that facilitate the
discussion. These include:
· A1, theso-called eutectoid temperature, which is the minimumtemperature for austenite
· A3
, the lower-temperature boundary of the austenite region at low carbon contents, that is, the γ/γ + α
boundary
· Acm, the counterpartboundaryfor high carbon contents, that is, the γ/γ + Fe3C boundary
Sometimes the letters c, e, or r are included. Relevant definitions of terms associated with phase transformations of steels
can be found in Table 2 as well as the Glossary of Terms in this Volume and Ref 3. The carbon content at which the
minimum austenite temperature is attained is called the eutectoid carbon content (0.77 wt% C). The ferrite-cementite
phase mixture of this composition formed during cooling has a characteristic appearance and is called pearlite and can be
treated as a microstructural entity or microconstituent. It is an aggregate of alternating ferrite and cementite lamellae that
degenerates ("spheroidizes" or "coarsens") into cementite particles dispersed with a ferrite matrix after extended hold
Monday, 3 June 2013
Build Lion of yourself
How to Strengthen
Character
edits by:Difu Wu,
Know Jesus, the Truth who shall set you free--fundamentally, Eric, Maluniu (see
all)
Article
Edit
Discuss
View History
Build your character to have strength like a
lion
Character, from the
Greek word "χαρακτήρα", was a term originally used for a mark
impressed upon a coin. Nowadays, it is known as the sum of all the attributes,
such as integrity, courage, fortitude, honesty, and loyalty, in a person.
Character is perhaps the most important essence a person can possess, as it
defines who a person is. To strengthen one's character is to mold oneself into
a productive person within one's sphere of influence. Here is some advice on
how to strengthen your own character, or to train your moral discipline.
edit
Steps
1
Strength of character is about freedom from
prejudices so that you love others as yourself, by extending yourself in
kindness and concern (freely, to the others' benefit).
Know what constitutes
strength in character. Strength in character consists of having the qualities
that allow you to exercise control over your instincts and passions, to master
yourself, and to resist the myriad temptations that constantly confront you.
Moreover, strength in character is freedom from biases and prejudices of the
mind, and is about displaying tolerance, love, and respect for others.
2
Strength in character allows you to accomplish
your goals.
Understand why
strength of character is important to yourself and especially to others:
Strength of character
allows you to carry out your will freely, while enabling you to cope with
setbacks. It assists you to accomplish your goals in the end.
It allows you to
inquire into the causes of ill-fortune, instead of just complaining about it,
as many are inclined to do.
It gives you the
courage to admit your own faults, frivolousness, and weaknesses.
It gives you the
strength to keep a foothold when the tide turns against you, and to continue to
climb upward in the face of obstacles.
3
Empathize with others.
The most important
way to strengthen your character is to empathize with others, especially the
weaker souls, and to love others as yourself. This may come at some cost,
causing you to examine your own motives so that you can empathize ungrudgingly.
Empathizing differs from sympathizing in connotation, as empathizing requires
you to project yourself and engage as needed (walk in and help clear the other
person's pathway);[1] whereas sympathy implies an emotional but passive
reaction, such as listening, looking and mimicking without extending oneself.
4
Favour strong reason, as Emmanuel Kant did.
Seek the truth.
Favour reason over pure emotion. The person with a strong character will
examine all the facts using the head, and not be biased by emotions from the
heart. Settle all matters upon reason alone, and avoid entangling yourself in
the chaos of your sensations.[2]
5
Be a leader.
Be neither a
pessimist nor an optimist, but a leader. A pessimist complains about the wind,
an optimist expects the adverse wind conditions to improve, but the leader
takes action to adjust the sails and ensure that they're ready to cope whatever
the weather.
6
Guard against irrational impulses, such as the
craving for sweets.
Guard against
irrational impulses. Aristotle and Aquinas considered that there are seven
human passions: love and hatred, desire and fear, joy and sadness, and anger.
While good in themselves, these passions can bypass our intellect and cause us
to love the wrong things eat too much food, fear things irrationally, or become
overwhelmed in sadness or by anger. The answer is found in always looking
before you leap and in practising good habits to free yourself from the
enslavement of your own passions. Inordinate, sensual appetites are the marks
of a weak character; the ability to delay gratification and practice self
control is a sign of strength.
7
Be content with what you have.
Be content with your
lot. Appreciate your own values and that which you have. Imagining that the
grass is greener somewhere else is a recipe for lifelong unhappiness; remember
that doing so is actually projecting your assumptions about how others live. It
is better to focus on how you live.
8
Be brave.
Be brave enough to
take calculated risks. If you shun the battle, you must forgo the victory, and
the joy associated therewith. Neither be cowardly, nor aloof, nor evade your
rightful duties, but be courageous so as to contribute your part to the
progress of humankind.
9
Fix on the right path, and walk therein,
turning neither to the left nor to the right.
Dismiss external
suggestions contrary to the resolution you are fixed upon. Every individual has
his or her interest foremost in mind, whether consciously or unconsciously. Neither
impose your will upon others, nor allow others to impose their will upon you.
Remain aware and accepting that different people will have different
suggestions, and that you cannot please everyone. Find the right path, and walk
therein, neither turn to the right nor the left. Govern yourself, and never
abandon the right path.
10
Learn to do good.
Learn to do good and
eschew evil. Seek peace and pursue it earnestly. Aim not for personal goals
that trample on others' needs, but aim after noble and worthy motives to
benefit society as a whole. If you seek personal gains, you will run into
conflicts with others, and, in the end, you will inevitably fail. If you seek
the mutual good, all will benefit, and you will also find satisfying personal
gains as well.
11
Master your feelings.
Learn to master your
feelings. Avoid letting anything other than sound reason dictate your decisions
in the conduct of everyday life. It might often be difficult, and at times
impossible, to not yield to feelings deep within your soul, but you can learn
to suppress their manifestations, and to overcome them through relying on
common sense and sound judgment.
12
Always seek the middle ground.
Be neither prodigal,
nor miserly, but seek the middle ground. The ability to seek the middle ground
is the mark of a strong character capable of resisting extremes.
13
Be calm, and you will have smooth sail.
Be calm in all
things. Calmness is a state of quietude that enables you to concentrate and
reassemble your divergent thoughts and meditate with profit. Contemplation
leads to ideas, and ideas lead to opportunities, and opportunities lead to
success. Calmness is a sine qua non of a strong character. Without calmness,
there can be no strength in character. Without calmness, passion can easily
become overheated, turning into an intense desire and interfering with sound
reason. Calmness is not the foe of feelings, but its regulator, permitting
their proper expression.
14
Be positive.
Focus on the
positives in life, and spare little time for the negatives. A physician once
said to a young woman complaining of all sorts of troubles for which she asked
of him a cure: "Don't think of them: it is the most powerful of all
cures." Physical and mental pains can be alleviated by effort of the will
to divert the mind into opposite channels, and exacerbated by the dwelling upon
them.
15
Oppose fatalism. You can change destiny by
adjusting the sails.
Oppose fatalism. Each
individual is responsible for his or her own development and fortune. To accept
fatalism, that is, to believe that destiny is somehow immovable, is to
discourage yourself from attempting all initiatives to improve your life and
self. Destiny is blind and deaf; it will neither hear nor regard us. Instead,
remember that fixing calamities and changing destiny for the better are ways to
strengthen your character and improve your lot in life. Work out your
happiness; don't wait for someone else or something else to do it for you because
it will never happen unless you persevere.
16
Be patient.
Have patience. An
individual with a strong character will not quit when faced with obstacles, but
will persevere to the end and overcome all obstacles. Learn to delay
gratifications in life, learn to wait, and learn that time is your friend. It
also helps to know which battles are worth it, and when to let things rest;
sometimes letting go is more important than clinging to a sinking ship.
17
Overcome all fears, such as the fear of
heights.
Conquer all fears.
Timidity is a stumbling block to success. Entertain no superstitions based upon
superficial observations, but accept facts based upon solid reason. Avoid
building your foundation upon sand, preferring instead to build upon a rock.
Once you overcome fear, you will have the strength of character to think, to
have resolve, and to act victoriously.
18
To grow a beautiful and fruitful garden like
this, you must clear the soil by removing all the weeds.
Just as a gardener
must remove all the weeds to grow the crops, so you must likewise dispel from
your mind all feeble thoughts, that act as weeds undermining your strength.
Guard against excessive emotions, and attribute to them their exact
significance. Whenever you find yourself preoccupied with some overwhelming
emotion, immediately occupy yourself with something else for fifteen minutes,
up to an hour. Many great warriors have lost their lives when they react too
brashly to insults, and go to fight prematurely against their taunters without
adequate preparations, acting merely upon a hot head. Learn to overcome such a
weakness with practice, remembering that anger is a common vice in all those of
weak character.
19
Have a business plan.
Exercise coolness,
circumspection, discernment, and prudence in business. Cultivate your mind with
logic, and conduct your affairs accordingly.
20
Be honest always.
Always be truthful in
all things and every aspect of life. If you are dishonest, you are dishonest
with yourself, and that is an assault upon your own character.
21
Work hard.
Finally, excel
wherever you are, and do your best in whatever you do. Work hard, and shun
idleness like the plague. By the same token, learn to appreciate quality
leisure time for its ability to rejuvenate and inspire you to return to your
good deeds.
Tips
Be happy.
Be happy. Happiness
is health. Happiness gives you strength to overcome the monotonous and dispel
boredom in life. It allows you to make the best of all things. Happiness is a
state of mind. It has been observed, that there are more smiles on the faces of
those of modest means, than on those of wealthy bankers on Wall Street.
Be a good friend.
Be a good friend.
Devote yourself to your friend, and be willing to sacrifice. Never hold
grudges, and dismiss all petty incidents. Live in harmony with others. Do not
be egoistic: always think in terms of others' interests.
Exercise!
Do physical exercise
to train your endurance. The mind and the body interconnect. So train your
physical endurance to strengthen your mental endurance.
Have discipline.
Have discipline and
self-control. Flee from bad impulses (including destructive works or actions
that one regrets later) -- and compulsive-obsessive behaviors that become a
habit and deform character.
Mechanical engineering semester 5 syallabus , mumbai university, mumbai, India
Fluid MechanicsT.E. Sem. V [MECH]
EVALUATION SYSTEM
Time Marks Theory Exam 3 Hrs. 100
Practical Exam 02(PE) 25
Oral Exam − 25
Term Work − 25
SYLLABUS
1. Fluid Definition and Properties
Concept of continuum, Newton’s law of viscosity, classification of fluid.
Fluid Statics
Definition of body forces and surface forces, static pressure, Pascal’s law, Derivation of basic
hydrostatic equation, Forces on surfaces due to hydrostatic pressure, Buoyancy and Archimedes
Principle.
2. Fluid Kinematics
Understanding of Eulerian and Lagrangian−approach to solutions, Velocity and acceleration in an
Eulerian flow field, Definition of streamlines, path lines and streak lines. Definition of steady /
unsteady, uniform / non−uniform, one two and three−dimensional flows. Understanding of
differential and integral methods of analysis. Definition of a control volume and control surface, types
of control volumes.
3. Fluid Dynamics
Equations for the control volume : Integral equations for the control volume; Reynolds transport
theorem with proof. Application to mass, energy and momentum transport (linear and angular).
Differential equations of the control volume: Conservation of mass (two and three dimensional).
Navier − Stokes equations (without proof) for rectangular and cylindrical co−ordinates. Exact
solution of Navier −stokes equations: viscous laminar flow of a fluid through a pipe, viscous laminar
flow of a fluid through planes (both stationary, one plane moving with a uniform velocity), Fluid flow
through concentric cylinders. Euler’s equations in two, three dimensions; Bernoulli’s equation.
Kinetic energy correction factor and momentum energy correction factor.
4. Ideal Fluid Flow Theory
Definition of stream functions and velocity potential functions, rotational and irrotational flows in
two dimensions, definition of source, sink, vortex,circulation. Combination of simple flow patterns−
e.g. flow past Rankine full body and Rankine half body, Doublet, flow past cylinder with and without
circulation, Kutta −Joukowsky law.
Real Fluid Flows
Definition of Reynolds number, Turbulence and theories of turbulence − Prandtl’s mixing length
theory, Eddy viscosity theory, k −epsilon theory. Velocity profiles for turbulent flows: one −seventh
power law, universal velocity profile, velocity profiles for smooth and rough pipes, Darcy’s equation
for head lost in pipe flows, pipes in series and parallel, hydraulic gradient line, Moody’s diagram.
5. Boundary Layer Flows
Concept of boundary layer and definition of boundary layer thickness, displacement thickness,
momentum thickness, energy thickness. Growth of boundary layer, laminar and turbulent boundary
K.G.C.E. KARJAT
layers, laminar sub−layer, Von−Karman momentum integral equations for the boundary layers,
analysis of laminar and turbulent boundary layers, calculation of drag., separation of the boundary
layer and methods to control it, concept of streamlined and bluff bodies. Aerofoil theory: definition of
an aerofoil, lift and drag on aerofoils, induced drag.
6. Introduction to Computational Fluid Dynamics
Basic concepts, Basic aspects of discretization. Grids with appropriate transformation, some simple
CFD techniques. Finite volume method of analysis, solutions to simple flow problems. Numerical
solution by means of an implicit method and pressure correction method.
References :
1. Fluid Mechanics (Streeter and Wylie)McGraw Hill
2. Mechanics of Fluid 3
rd
edition (Merle Potter, David Wiggert)Cengage Learning
3. Fundamental of Fluid Mechanics 5
th
edition (Munson)Wiley
4. Fluid Mechanics (Frank M. White)McGraw Hill
5. Fluid Mechanics (Cengel, Yunus, Bhattacharya, Souvik)McGraw Hill
6. Fluid Mechanics (K.L. Kumar)
7. Introduction to Computational Fluid Dynamics (Niyogi)Pearson Education
8. An Introduction to Computational Fluid Dynamics The Finite Volume Method 2
nd
edition (Versteeg)
Pearson Education
9. Introduction to Fluid Mechanics 5
th
edition (Fox)Wiley
10. Introduction to Fluid Mechanics, (Shaughnessy)et al, OxFord
11. Introduction to Fluid Mechanics and Fluid Machines 2
nd
ed., Tata McGraw Hill
12. Fluid Mechanics (Yunus Cengel and John Cimbala) Tata McGraw Hill.
13. Advanced Fluid Dynamics (Muralidhar and Biswas)
14. Fluid Mechanics (Douglas)et.al. 5
th
, Pearson Education
15. Computational Fluid Dynamics (John Anderson)McGraw Hill
16. Fluid Mechanics with Engineering Applications (John Finnemore, Joseph Franzini)McGraw Hill
17. 1000 Solved Problems in Fluid Mechanics (K. Subramanya)Tata McGraw Hill
Graphic User Interface and Database Management
T.E. Sem. V [MECH]
EVALUATION SYSTEM
Time Marks Theory Exam − −
Practical Exam 04(PE) 50
Oral Exam − 50
Term Work − 50
SYLLABUS
1. GUI
Murphy ’s Law of GUI Design, Features of GUI, Iconsand graphics, Identifying visual cues, clear
communication, color selection, GUI standard, planning GUI Design Work. Goal Directed Design,
Software design, Visual Interface design, Menus, Dialog Boxes, Toolbars, Gizmo- laden dialog
boxes, Entry gizmos, extraction gizmos, visual gizmos.
Visual programming; Software Component Mindset-role of programming code.
2. VB. Net
Building objects : Understanding objects, building classes, reusability, constructor, inheritance the
frame work classes.
Advanced Technique : Building a favorites viewer using shared properties and methods,
understanding OOP and memory management Building class libraries:- Understanding class libraries,
Using strong names, Registering assemblies, Designing class libraries.
Creating your own custom controls : Windows forms control, Exposing properties from user control,
Inheriting control behavior, Design time or run time, Creating a Form Library.
Accessing Database : Data Access components, Data Binding.
Database Programming : ADO.NET, The ADO.NET Classes in action, Data Binding − Unit
References. BVB.Net
3. Data base concepts and Systems
Introduction : Purpose of Database Systems, Views of data, Data Models, database language,
Transaction Management, Storage Management, Database Administrator, Database Users, Overall
System Structure, Different types of Database Systems.
4. E− −− −R Model :Basic Concepts, Design Issues, Mapping Constraints, Keys, E−R Diagram, Weak Entity set,
Extended E−R features, Design of an E−R Database Schema, Reduction of an E−R schema to Tables.
Relational Model :Structure of Relational Database, The Relational Algebra, The tuple relational
calculus, The Domain Relational Calculus, Views.
5. SQL : background, Basic Structure, SET operations, Aggregate functions, Null Values, Nested Sub
queries, Derived Relations, Views, Modification of Database, Joined Relations, DDL, other SQL features.
Transaction : Transaction Concepts, State, Implementations of Atomicity and durability, Concurrent
Executions, Serializability, Recoverability, Transaction Definition in SQL.
Concurrency Control : Lock based protocol, Timestamp based protocol, Validation based protocol,
Multiple Granularity, Multi version Schemes, Deadlock Handing, Insert and Delete operations,
Concurrency in index structure.
6. SQL SERVER
SQL Server Database Architecture- physical Architecture- logical Architecture
SQL Server administration tasks and tools – The SQL Server Enterprise Manager
Security and user administration, SQL Server Command −Line utilities, Database Maintenance Data
base design and performance.
K.G.C.E. KARJAT
References:
1. Using visual basic 6 / (Reselman, Rob: Peasjey, R.Pruchniak)Prentice Hall India pvt. Ltd.,
2. Visual Basic 6: In Record Time/ (Brown), S.B P B Publication
3. SQL Server 2000 Black Book (Patrick Dalton, Paul Whitehead)dreamtech press
4. Beginning SQL Server 2000 for Visual Basic Developers Willis thearon Shroff publishers
5. An Introduction to Database System (C.J. Date)
6. Principles of Database System, (Ullman), Galgotia Publications
7. Database Management Systems (Majumdar / A K Bhattacharyya)Tata Mc Graw Hill
8. Object Oriented MultiDatabase System (Omran A. Bukhares & A.K. Elmagarmid)Prentice Hall
9. Database Systems and Concepts, (Henry F. Korth, Sliberschatz, Sudarshan)McGraw Hill
10. DBMS by Date
11. Visual Basic 6 Programming Bible (Eric Smith)IDG Books India Pvt. Ltd.
12. Visual Basic 6 Programming Black Book (Steven Holzner)IDG Books India
13. GUI Design for dummies, IDG books.
14. The Essentials of User interface Design, (Alan Cooper)IDG Books India
15. SQL Server 2000 Black gook (Patrick Dalton)IDG Books India Pvt.
16. Visual Basic 6 Programming Blue Book by (Peter G. Aitken)Technology Press
17. Microsoft SQL Server 7.Q Bjeletich S.: (Mable G. Techmedia)
Heat and Mass Transfer
T.E. Sem. V [MECH]
EVALUATION SYSTEM
Time Marks Theory Exam 3 Hrs. 100
Practical Exam − −
Oral Exam − 25
Term Work − 25
SYLLABUS
1. Conduction
Mechanism of heat transfer by Conduction. Fourier’s three−dimensional differential equation for
Conduction with heat generation in unsteady state in the Cartesian co−ordinates. Solution of Fourier’s
equation for one−dimensional steady state Conduction through isotopic materials of various configurations
such as plane wall, plane composite wall, cylindrical and spherical composite walls. (For cylindrical and
spherical walls, derivation of Fourier’s three −dimensional equation is NOT included.)
2. Unsteady state Conduction through a plane wall having no internal resistance. Users of Heisler charts.
Extended surfaces. Solutions for heat transfer through rectangular fins. Types if fins and their
applications. Effectiveness and efficiency of fins.
3. Convection
Mechanism of heat transfer by convection. Natural and Forced convection. Hydrodynamic and
thermal boundary layers. Similarity between velocity profile and temperature profile. Heat transfer
coefficient (film coefficient) for Convection. Effect of various parameters such as physical properties
of the fluid, system geometry, fluid flow etc. on heat transfer coefficient. Heat pipe−Introduction
and application. Principle of dimensional analysis. Application of dimensional analysis to
Convection for finding heat transfer coefficient. Empirical relations for Convection. Physical
significance of dimensionless numbers such as Nusselt’s Number, Grashoff’s Number, Prendtl’s
Number, Reynolds Number and Stanton’s Number. Reynolds analogy between momentum and heat
transfer. 2.8. Heat transfer in condensation. Nusselt’s theory of laminar film Condensation. Heat
transfer in boiling Curve & critical heat flux.
4. Radiation
Mechanism of heat transfer by Radiation. Concept of black body and grey body. Emissive power and
Emissivity. Basic laws of Radiation: Planck’s law,Kirchoff’s law, Stefan −Baoltzman law, Wien’s−
displacement law and Lambert’s Cosine law. Intensity of Radiation Radiosity. Radiation heat
exchange between two black bodies. Electrical network analogy for radiation heat exchange between
two and three grey bodies. Shape factor for simple geometries. Properties of shape factor.
5. Heat Exchangers
Classification of heat exchangers. Logarithmic Mean Temperature Difference, Correction factor and
effectiveness of heat exchangers. Effectiveness asa function of Number of Transfer Units and heat
capacity ratio. Overall heat transfer coefficient,Fouling factor.
6. Mass Transfer
Mechanism of mass transfer. Importance of mass transfer in engineering. Fick’s law of diffusion.
Steady State diffusion of gases and liquids throughplane, cylindrical and spherical walls. Equimolal
diffusion. Isothermal evaporation of water into air. Convective mass transfer and mass transfer
coefficient. Empirical relations for mass transfer,in terms of Sherwood Number, Reynolds Number
and Schmidt’s number.
K.G.C.E. KARJAT
References:
1. Elements of Heat Transfer (Jakole and Hawkins)
2. Heat Transfer (James Sucec)JAICO Publishing House
3. Heat Transfer (Donald Pitts & L.E. Sisson Schaums Series)McGraw Hill International
4. Engineering Heat Transfer (James R. Weity)
5. Engineering Heat Transfer (Shao Ti Hsu)
6. Heat and Mass Transfer (Eckert and Drake)
7. Heat Transfer (M.Necati Ozisik)McGraw Hill int. education
8. Heat Transfer (Incropera and Dewitt)Wiley India
9. Fundamentals of Momentum, Heat and Mass Transfer4
th
ed.(Welty)Wiley India
10. Engineering Heat Transfer N.V.Suryanarayana Penram publication
11. Heat Transfer (S.P. Sukhatme)University Press
12. Heat Transfer (Ghosdastidar)Oxford University press.
13. Heat Transfer 9
th
ed. (J.P.Holman)McGraw Hill
14. Principles of Heat Transfer 6
th
ed., (Frank Kreith)CENGAGE Learning
15. Heat and Mass Transfer (C.P.Arora) Dhanpatrai and Co.
16. Heat and Mass Transfer (Prof. Sachdeva)
17. Heat and Mass Transfer (R. Yadav)
18. Heat Transfer (Y.V.C. Rao)University Press
19. Heat and Mass Transfer (R.K.Rajput)S.Chand & Company Ltd.
20. Fundamentals of Heat and Mass Transfer Incropera Wiley India
21. Heat and Mass Transfer (Domkundwar)Dhanpatrai and Co.
22. Heat and Mass Transfer 2
nd
ed. (Nag P.K.)Tata McGraw Hill
23. Introduction to Thermodynamics and Heat Transfer with ESS Software 2
nd
ed.(Yunus A. Cengel)
McGraw Hill International
24. Fundamentals of Heat and Mass Transfer (Thirumaleshwar)Pearson Education
Mechanical Measurement & Metrology
T.E. Sem. V [MECH]
EVALUATION SYSTEM
Time Marks Theory Exam 3 Hrs. 100
Practical Exam − −
Oral Exam − 25
Term Work − 25
SYLLABUS
1. Significance of Mechanical Measurements, Classification of measuring instruments, generalized
measurement system, types of inputs: Desired, interfering and modifying inputs.
Static characteristics: Static calibration, Linearity, Static Sensitivity, Accuracy, Static error,
Precision, Reproducibility, Threshold, Resolution, Hysteresis, Drift, Span & Range etc.
Error in measurement: Types of errors, Effect of component errors on combination and distribution
of combination errors on components, Probable errors.
2. Displacement measurement: Transducers for displacement measurement, Potentiometers, LVDT,
Capacitance type, Digital transducers (optical encoder), Nozzle flapper transducer.
Strain measurement: Theory of Strain Gauges, Gauge factor, Temperature compensation, Bridge
circuit, Orientation of Strain Gauges for Force andTorque measurement, Strain Gauge based Load
Cells and Torque Sensors.
3. Measurement of angular velocity: Tachometers, Tachogenerators, digital tachometers and
Stroboscopic methods.
Pressure measurement: Pressure standards, Elastic pressure transducers viz. Bourdon Tubes,
Diaphragm, Bellows and piezoelectric pressure sensors. High−pressure measurements, Bridgman
gauges Calibration of pressure sensors.
Vacuum measurement: Vacuum gauges viz. McLeod gauge, Ionization and Thermal Conductivity
gauges.
4. Acceleration Measurement: Theory of accelerometers and vibrometers. Practical Accelerometers,
strain gauge based and piezoelectric accelerometers.
Temperature measurement: Thermodynamic Temperature Scale and IPTS. Electrical methods, of
temperature measurement, Resistance thermometers, Thermistors and Thermocouples, Pyrometers.
5. Metrology
Standard of measurement, line and end standards wave length standard, working standards,
requirements of interchangeability, allowance and tolerance, limits and fits, B.S. and I.S.
specifications for limits and fits, limits gauging, automatic gauging, needs in semi−automatic,
automatic production, principle of operation, features of in process gauging system.
6. Use of comparators such as mechanical, optical, electrical, electronics and pneumatic. Angular
measurements, angle gauges, sine bar, levels, clinometers and taper gauges. Metrology of screw
threads, limits gauging of screw threads. Gear measurements. Measurement of flatness and square
ness, surface finish definition and measurement of surface texture, study and use of profile projector
and tool maker’s microscope, dividing head and auto−collimator.
K.G.C.E. KARJAT
References :
1. Experimental Methods for Engineers (J.P.Holman)McGraw Hills Int. Edition.
2. Engineering Experimentation (E.O.Doeblin)McGraw Hills Int. Edition.
3. Mechanical Measurements (S.P.Venkateshan)Ane books, India
4. Metrology for Engineers (J.F.W Galyer & C.R.Shotbolt)
5. Theory and Design for Mechanical Measurements, 3
rd
ed., Wiley
6. Principals of Engineering Metrology (Rega Rajendra)Jaico. Publication
7. Measurement Systems (Applications and Design) 5
th
ed.- (E.O. Doebelin)−McGraw Hill.
8. Dimensional Metrology, (Connie Dotson), CENGAGE Learning
9. Mechanical Engineering Measurement (Thomas Beckwith, N.Lewis Buck, Roy Marangoni) Narosa
Publishing House, Bombay.
10. Mechanical Engineering Measurements (A.K.Sawhney)−Dhanpat Rai & Sons. New Delhi.
11. Instrumentation Devices & Systems (C.S. Rangan & G.R.Sarrna)Tata McGraw Hill.
12. Instrumentation & Mechanical Measurements (A.K.Thayal)
13. Engg. Metrology (R.K.Jain)
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