Figure1.1 Universal testing machine

Figure1.2 Standard tensile test specimen

TENSION TESTEX: NO: 1

DATE:

AIM:To observe the stressstrain relation of a mild steel rod by performing a tensile test.APPARATUS REQUIRED:1. Universal testing machine2. Vernier caliper3. Steel rule 4. Mild steel rod.FORMULAE USED:1. Youngs modulus = N/ mm 2. Yield stress = N/ mm3. Ultimate tensile stress = N/ mm4. Breaking stress (Engineering) = N/ mm5. Breaking stress (True) = N/ mm6. % Elongation = 100 %7. % Reduction in area = 100 %Where, = Final length (mm) = Original length (mm)= Final Area (mm)= Original Area (mm)

Figure1.3 Typical stress- strain diagram

TABLE: 1LC = mmDiameterMain Scale Reading (mm)Vernier Scale CoincidenceVernier Scale Reading (mm)Diameter of the rod (mm)Average diameter(mm)

Before fracture

after fracture

THEORY:The engineering tension test is widely used to provide basic design information on the strength of the materials and as an acceptance test for the specification of materials. In tension test a specimen is subjected to a continually increasing uniaxial tensile force while simultaneous observations are made of the elongation of the specimen. An engineering stress-strain curve is constructed from the load-elongation measurements. The shape and magnitude of the stress-strain curve of a metal will depend on its composition, heat treatment, strain rate, temperature, and state of stress imposed during the testing. The parameters which are used to describe the stress-strain curve of a metal are the tensile strength, yield strength, percent elongation and reduction of area. The first two are strength parameters; the last two indicate ductility.This test is mainly used to determine strength, ductility, toughness, resilience and other mechanical properties. The machine used for tensile testing is the universal testing machine.PROCEDURE:1. The diameter of the given rod is measured at three places using vernier caliper2. The gauge length is marked over the mild steel rod3. The specimen is gripped in the machine and set the extension measuring device to zero4. The machine is switched on and the specimen is loaded gradually5. The various load reading and the corresponding elongation are record6. Repeat the procedure till the specimen fractures.7. The final length and final diameter is measured by joining the broken specimen

TABLE: 2S.noLoad(N)Original length (mm)Final length(mm)Change in length (mm)Stress (N/mm2)Strain

CALCULATION:

RESULT:Tension test on mild steel rod was conducted and the following results were obtained. The graph stress Vs strain was plotted 1. Youngs modulus = N/ mm 2. Yield stress = N/ mm3. Ultimate tensile stress = N/ mm4. Breaking stress (Engineering) = N/ mm5. Breaking stress (True) = N/ mm6. % Elongation in length= %7. % Reduction in area = %

REVIEW QUESTIONS:1. What is proportional limit?2. What is Hookes law?3. Say yes or no and give proper reason for the following statement. For brittle materials ultimate tensile stress is the breaking stress.4. What is yield stress and where is it applied in real time application?5. Differentiate Resilience and Toughness?

Figure2.1 Shear stress diagram

DOUBLE SHEAR TEST

EX: NO: 2

DATE:

AIM:To conduct double shear test on given specimens.EQUIPMENTS REQUIRED:1. UTM with double shear chuck2. Vernier Caliber3. Test SpecimenFORMULA USED:Shear strength = N/ mm2THEORY:A common application of metals in engineering design is in shear loading. Bolts, rivets, and drive keys are loaded in such a manner as to cleave the material in half. The shear strength of a material is the stress at which a shear loaded member will fail. That is, the stress required to produce fracture when a member is subjected to two equal and opposite forces which are acting tangentially across the resisting section. The application of the property of shear strength in machine design is obvious. It is the property, that must be considered on shear loaded fasteners and the like. Shear strength 40% of the tensile strengthA shear test can be performed in a tensile testing machine with special attachments.

OBSERVATION 1: (MILD STEEL ROD)1. Diameter of the specimen (d) = mm2. Load taken at the time of shear failure (P) = KN.

OBSERVATION 2: (ALUMINIUM ROD)1. Diameter of the specimen (d) = mm2. Load taken at the time of shear failure (P) = KN.

CALCULATION:

PROCEDURE:1. Measure the diameter of the hole accurately.2. Insert the specimen in position and grip one end of the attachment in the upper portion and the other end in the lower portion.3. Switch on the main switch on the universal testing machine.4. Bring the drag indicator in contact with the main indicator.5. Gradually move the head control lever in left hand direction till the specimen shears.6. Note down the load at which specimen shears.7. Stop the machine and remove the specimen.

PRECAUTION: The inner diameter of the hole in the shear stress attachment is slightly greater than that of the specimen.

RESULT:1. Shear strength of the given Specimen1 ( ) = kg/mmN / mm2 2. Shear strength of the given Specimen2 ( ) = kg/mmN / mm2

REVIEW QUESTIONS:1. What is shear strength?2. What is meant by double shear?3. What is the use or need of finding shear strength of the material?4. Name some engineering parts/ components are subjected to shear force, when they are in service.

Figure3.1 Torsion testing Machine

TORSION TEST

EX: NO: 3

DATE:

AIM: To determine the modulus of rigidity, polar moment of inertia, and twisting moment, torsional rigidity maximum shear stress induced of the given mild steel rod.APPARATUS REQUIRED:1. Torsion testing machine2. Vernier caliper3. Specimen

FORMULAE USED:1. Torsion Equation = = = 2. Polar Moment of Inertia = mm43. Torsional rigidity = N mm/ radWhere,T = Twisting moment or Torque (Nm)J = Polar Moment of Inertia (mm4)C = Modulus of rigidity (N/ mm) = Angle of twist (radian)L = length of the rod (mm)R = Radius of the rod (mm) = Maximum shear stress induced on rod (N/ mm)

THEORY:

A Shaft is said to be in torsion, when equal and opposite torques are applied at the two ends of the shaft. The torque is equal to the product of the forces applied and radius of the shaft. Due to the application of torques at the two ends, the shaft is subjected to a twisting moment. This causes the shear stresses and shear strains in the material of the shaft. The theory of pure torsion is based on the following assumptions. The material of the shaft is uniform throughout.TABULATION:S.noTorque(Nm)Angle of twistTorsion of rigidity (Nmm2)Maximum shear stress inducedN/mm2

DegreeRadian

The twist along the shaft is uniform. The shaft is of uniform circular cross section throughout. Cross sections of the shaft, which are plane before twist, remain plane after twist. All radii which are straight before twist remain straight after twist.The maximum torque transmitted by a circular shaft, is obtained from the maximum shear stress induced at the outer surface of the solid shaft.

PROCEDURE:

1. Measure the diameter of the given specimen using vernier caliper.2. Measure the length of the specimen accurately after securing the specimen into the machine.3. Set the initial torque and angle of twist to zero.4. Note the values of the torque for every 10 angle of twist.5. Note the values of torque till the specimen fails.6. Using the formulae determine the modulus of rigidity, modulus of rupture, maximum stress induced, torsional rigidity and polar moment of inertia of the given specimen.

CALCULATION

RESULT:

1. Modulus of rigidity = __________N/mm22. Torsional rigidity at torque ______Nm = ________ Nmm23. Maximum shear stress induced at torque ______Nm = ________ N/mm2

REVIEW QUESTIONS:1. What is twisting moment?2. Define torsional rigidity.3. Name some engineering components/ parts, which are subjected to torsion when they are in actual service.4. What is polar moment of inertia?5. Differentiate polar moment of inertia and mass moment of inertia.6. When the shaft is subjected to torsion, where the induced shear stress will be high?

Figure 4a.1 Izod impact testing Machine

IZOD IMPACT TESTEX: NO: -4aDATE:

AIM:To determine the Impact strength of the given metal specimen using Izod impact testing machine.APPARATUS REQUIRED:1. Impact testing machine, 2. Mild Steel specimen of 751010 mmFORMULA USED:Impact strength = J/mmTHEORY: Impact strength is used to measure a materials ability to withstand shock loading. The classical definition of impact strength is the energy required to fracture a given volume of material. In metals and polymers the impact strength is most commonly measured by a pendulum type impact machine. For most metals the specimen has a notch in it to prompt fracture in the desired spot. The principle used in impact testing machine is that a notched specimen with a standard blow from a pendulum hammer absorbs certain amount of energy before it breaks and the energy absorbed by the specimen during impact measures its impact strength. Impact test evaluates the toughness of the material. Toughness is the ability of a material to absorb energy during plastic deformation. Toughness is a measure of both strength and ductility of the material. If the material is tough it absorbs more energy and so it requires more energy in order to fracture. If it is brittle it absorbs less energy and so it breaks more easily.The impact testing machine is the same for both izod and charpy test. The difference is in the size and the holding of the specimen.

Figure 4a.2 Izod impact test

CALCULATION:

Initial energy of pendulum = Energy necessary to Swing energy offracture the specimen + pendulummgH = Toughness + mghTopughness = mg (H-h)= W (H-h)Where,W = weight of pendulum (kg)H= Original height of the pendulum (m)h= swing height (height reached after breaking the specimen) of pendulum (m)PROCEDURE:1. With the striking hammer in sate position, hold the work piece firmly in the impact testing machine vice in such a way that the notch faces the hammer and is half inside and half above the top surface of the vice.2. Bring the striking hammer to top most position unless if is already there, and lock it.3. Bring the indicator to zero and then release the striking hammer. It will fall due to gravity and break the specimen. The total energy is not absorbed by the specimen. The pendulum continues to swing. At its topmost height after breaking the specimen, the indicator stops moving, while, the pendulum falls back. Note the indicator reading at that top most position.4. Again bring the striker to its idle position and lock.

PRECAUTION:1. The notch should be properly machined.2. The test piece should be properly placed on the machine support.3. The pendulum must swing freely over the horizontal axis of rotation.4. Friction effort should be taken into account.5. Operators should not stand in the swinging zone of the pendulum.

RESULT:The impact strength of the given specimen = kg - m

Review questions:1. What is Toughness?2. What is the use or need of finding Toughness of the material?3. Name some engineering parts/ components subjected to shock load when they are in actual service..4. Differentiate Izod and charpy tests5. What is the purpose of notching the specimen?

Figure 4b.1 Charpy impact testing Machine

CHARPY IMPACT TESTEX: NO: -4b

DATE

AIM:To determine the Impact strength of the given metal specimen using Charpy impact testing machine.APPARATUS REQUIRED:3. Impact testing machine, 4. Mild Steel specimen of 751010 mmFORMULA USED:Impact strength = J/mmTHEORY: Impact strength is used to measure a materials ability to withstand shock loading. The classical definition of impact strength is the energy required to fracture a given volume of material. In metals and polymers the impact strength is most commonly measured by a pendulum type impact machine. For most metals the specimen has a notch in it to prompt fracture in the desired spot. The principle used in impact testing machine is that a notched specimen with a standard blow from a pendulum hammer absorbs certain amount of energy before it breaks and the energy absorbed by the specimen during impact measures its impact strength. Impact test evaluates the toughness of the material. Toughness is the ability of a material to absorb energy during plastic deformation. Toughness is a measure of both strength and ductility of the material. If the material is tough it absorbs more energy and so it requires more energy in order to fracture. If it is brittle it absorbs less energy and so it breaks more easily.The impact testing machine is the same for both izod and charpy test. The difference is in the size and the holding of the specimen.

Figure 4b.2 Charpy impact test

CALCULATION:

Initial energy of pendulum = Energy necessary to Swing energy offracture the specimen + pendulummgH = Toughness + mghTopughness = mg (H-h)= W (H-h)Where,W = weight of pendulum (kg)H= Original height of the pendulum (m)h= swing height (height reached after breaking the specimen) of pendulum (m)PROCEDURE:1. With the striking hammer in sate position, hold the work piece firmly in the impact testing machine vice in such a way that the notch faces the hammer and is half inside and half above the top surface of the vice.2. Bring the striking hammer to top most position unless if is already there, and lock it.3. Bring the indicator to zero and then release the striking hammer. It will fall due to gravity and break the specimen. The total energy is not absorbed by the specimen. The pendulum continues to swing. At its topmost height after breaking the specimen, the indicator stops moving, while, the pendulum falls back. Note the indicator reading at that top most position.4. Again bring the striker to its idle position and lock.PRECAUTION:1. The notch should be properly machined.2. The test piece should be properly placed on the machine support.3. The pendulum must swing freely over the horizontal axis of rotation.4. Friction effort should be taken into account.5. Operators should not stand in the swinging zone of the pendulum.

RESULT:The impact strength of the given specimen = kg - m

REVIEW QUESTIONS:1. What is Toughness?2. What is the use or need of finding Toughness of the material?3. Name some engineering parts/ components subjected to shock load when they are in actual service.4. Differentiate Izod and charpy tests5. What is the purpose of notching the specimen?

BRINELL HARDNESS TESTEX: NO: 5a.DATE:

AIM: To find the Brinell Hardness Number for the given metal specimen.EQUIPMENTS REQUIRED:1. Brinell Hardness Testing Machine2. Metal Specimens3. Brinell Microscope.FORMULAE USED:1. Brinell Hardness Number (BHN) = 2. (A)= Where,P = Load applied in kgf.D = Diameter of the indenter in mm.D = Diameter of the indentation in mm.THEORY:The hardness of the materials is often equated with the wear resistance and durability. It serves as a measure of abrasion resistance and strength. Hardness may be defined as resistance of metal to plastic deformation usually by indentation. However the term may also refer to stiffness or temper or resistance to scratch, abrasion or cutting. There are three general types of hardness measurements depending upon the manner in which the test is conducted.1. Scratch hardness measurement.2. Rebound hardness measurement.3. Indentation Hardness measurement.

Figure 5a.2 Brinell hardness test

Tabulation:Sl.No.Specimen MaterialLoad in (kgf)Diameter of ball (mm)Indentation Diameter (mm)Average of Indentation Diameter(mm)Brinell Hardness Number (BHN)

In scratch hardness method, the materials are rated on their ability to scratch one another and mineralogists use it. In rebound hardness measurement, a standard body is usually dropped on to the material surface and the hardness is measured in terms of the height of its rebound. The general means of judging the hardness is the resistance of a material to indentation. Indentation hardness may be measured by various hardness tests such as Brinell, Rockwell, etc. The Brinell hardness test consists in indenting the metal surface with a 10 mm diameter steel ball at a load of 3000 kg. For soft metals the load is reduced to 500 kg to avoid too deep an impression, and for very hard metals a tungsten carbide ball is used to minimize distortion of the indenter. The load is applied for a standard time, usually 30s, and the diameter of the indentation is measured with a low power microscope after removal of the load. The average of the readings of the diameter of the indentation at right angles should be made. The surface on which the indentation is made should be relatively smooth and free from dirt or scale. The large size of the Brinell impression may preclude the use of this test with small object or in critically stressed where the indentation could be a potential site of failure.

CALCULATION:

Precautions:1. Brinell test should be performed on smooth, flat specimens from which dirt and scale have been cleaned.2. The test should not be made on thin specimens so that the impression shows through the metal, nor should impressions be made too close to the edge of the specimen.Procedure:1. Specimen is placed on the anvil. The hand wheel is rotated so that the specimen along with the anvil moves up and contact with the ball. 2. The desired load is applied mechanically (by gear driven screw) and the ball presses into the specimen.3. The diameter of the indentation made in the specimen by the pressed ball is measured by the use of a micrometer microscope, having transparent engraved scale in the field of view.4. The indentation diameter is measured at two places at right angles to each other, and the average of two readings is taken.5. The Brinell Hardness Number (BHN) which is the pressure per unit surface area of the indentation is noted down.

Result:1. The Brinell Hardness for specimen1( ) = kg/mm2. The Brinell Hardness for specimen2( ) = kg/mm3. The Brinell Hardness for specimen3( ) = kg/mm

Review questions:1. What is Hardness?2. What is the use or need of finding hardness of the material?3. Drive the formula of surface area of indentation.4. Name some engineering parts/ components requires more hardness value5. What is disadvantage of Brinell Hardness testing?

Figure 5b.1 Rockwell hardness tester

ROCKWELL HARDNESS TEST.

EX: NO: 5b

DATE:

AIM :

To determine the Rockwell Hardness Nnmber for the given metal specimen.EQUIPMENTS REQUIRED:1. Rockwell Hardness Testing Machine.2. Metal Specimen.THEORY:The hardness of the materials is often equated with the wear resistance and durability. It serves as a measure of abrasion resistance and strength. Hardness may be defined as resistance of metal to plastic deformation usually by indentation. However the term may also refer to stiffness or temper or resistance to scratch, abrasion or cutting. There are three general types of hardness measurements depending upon the manner in which the test is conducted.4. Scratch hardness measurement.5. Rebound hardness measurement.6. Indentation Hardness measurement.

In scratch hardness method, the materials are rated on their ability to scratch one another and mineralogists use it. In rebound hardness measurement, a standard body is usually dropped on to the material surface and the hardness is measured in terms of the height of its rebound. The general means of judging the hardness is the resistance of a material to indentation.Indentation hardness may be measured by various hardness test such as Brinell, Rockwell, etc. Rockwell hardness testing differs from Brinell testing. In Rockwell testing, the indenters and loads are smaller and therefore the resulting indentation on the specimen is smaller and shallower. The Rockwell machine gives arbitrary direct reading, Unlike Brinell testing,

Figure 5b.2 Rockwell hardness test

Rockwell testing needs no surface preparation (Polishing) of the specimen whose hardness is to be measured.Rockwell hardness is dependent on the load and indenter. So it is necessary to specify the combination which is used. This is done by prefixing the hardness with a letter indicating the particular combination of load and indenter for hardness scale employed. A Rockwell hardness number without the letter prefix is meaningless. Hardened steel is tested on the C scale with the diamond indenter (120 diamond cone with a slightly rounded point) and a 150kg major load. The useful range for this scale is from about RC 20 to RC 70. Softer materials are usually tested on the B scale with a diameter steel ball and a 100 kg major load. T he range for this scale is from RB 0 to RB 100. The A scale ( diamond indenter, 60 kg major load) provides the most extended Rockwell hardness scale, which is usable for materials from annealed brass to cemented carbides.A minor load of 10 kg is first applied to seal the specimen. This minimizes the amount of surface preparation needed and reduces the tendency for ridging or sinking by the indenter. The major load is then applied, and the depth of indentation is automatically recorded on a dial gauge in terms of arbitrary hardness numbers. The dial contains 100 divisions, each division representing a penetration of 0.00008. The dial is reversed so that a high hardness, which corresponds to a small penetration, results in high hardness number.Precautions: 1. The indenter and anvil should be cleaned and well seated2. The surface to be tested should be clean and dry, smooth and free from oxide. A rough-ground surface is usually adequate for Rockwell test.3. The surface should be flat and perpendicular to the indenter.4. It is recommended that the thickness of the test specimen must be atleast 10 times the depth of the indentation. So that the mark or bulge is not produced on the reverse side of the specimen.5. The space between the indentations should be three or five times the diameter of the indentation.

TABULATIONSl.NoSpecimen MaterialType of IndenterLoad (kgf)Rockwell Hardness Number (RHN)Rockwell Hardness Number (HRC)

MinorMajorTotal123

PROCEDURE:1. Test piece is placed upon the machine. The dial may be showing any reading.2. Hand wheel is turned; thereby raising the test piece up against the steel ball indenter till the needle of the small dial is against the red mark. This applies minor load.3. Major load is applied by pressing the crank provided on the right hand side of the machine. Time is given as 30 sec so as to make the load reach specimen fully.4. When the penetration is completed, the crank is turned in the reverse direction thereby with drawing the minor load but the leaving the major load applied.5. The pointer moves further and becomes stand still. This reading is taken as Rockwell Hardness Number C scale.( HRC)6. Hand wheel is rotated and the test piece is lowered.

RESULT:Rockwell Hardness number of the specimens was found for the given material as follows:1. Copper= HRC2. Brass= HRC3. Aluminium= HRC.

REVIEW QUESTIONS:1. What is Hardness?2. What is the use or need of finding hardness of the material?3. Name some engineering parts/ components requires more hardness value4. What are the advantages of Rockwell hardness testing over Brinell hardness testing?

DEFLECTION TEST ON BEAMSEX: NO: 6

DATE:

AIM:To conduct deflection test on beam and verify Maxwells reciprocal theorem.APPARATUS REQUIRED:1. Wooden Beam with its support2. Wooden scale3. Dial gauge(5mm range)4. Weights5. Weight hangerTHEORY:Maxwells reciprocal theorem. States that, The deflection at a point A due to an unit force at a point B is equal to the deflection at point B due to unit force at A.PROCEDURE:1. The given beam is placed on the supports.2. Two points are chosen on the beam say A and B3. A dial gauge is fixed at the point B4. The initial reading of the dial gauage is noted.5. Standard weights are added at the point A and dial guage readings are taken for each load increments6. After the loading is completed the weights are slowly remeoved and the corresponding defection is noted.7. Plot a graph between deflection (X-axis) and load ( Y-axis ) and find the slope8. Keeping the dial guage at point A and adding the weight at point B repeate the same procedure.

TABULE: 1 (Load at A and deflection at B)S. noLoad(gm)Deflection reading (div)Actual deflection(mm)Average deflection(mm)

LoadingUnloading

TABULE: 1 (Load at B and deflection at A)S. noLoad(gm)Deflection reading (div)Actual deflection(mm)Average deflection(mm)

LoadingUnloading

RESULT: The slope of both the graphs is same. From this Maxwells theorem is verified.

Figure7.1 Compression test on springs

OBSERVATION:1. Least count of vernier caliper = mm2. Diameter of spring wire, d = mm3. Outer diameter of spring coil, Do = mm4. Inner diameter of spring coil, Di = mm5. Mean diameter of spring coil, D = .mm6. Number of turns, n =

COMPRESSION TEST ON HELICAL SPRINGEX: NO: 7

DATE:

AIM: To determine Stiffness, Modulus of rigidity, and Shear stress for the given open coiled helical spring.APPARATUS REQUIRED:1. Spring testing machine2. Steel rule 3. open coiled spring4. Vernier caliperFORMULAE USED:1. Stiffness, s = N/mm2. Modulus of rigidity, C = N/ mm3. Maximum Shear stress induced on the spring, = N/ mmWhere,W = Applied load (N) = Deflection (mm)D = Mean Diameter of spring coil (mm)d = Diameter of spring wire (mm)n = Number of coils

THEORY:Springs are the elastic bodies which absorb energy due to resilience. The absorbed energy may be released as and when required. A spring is capable of absorbing greatest amount of energy for the given stress, without getting permanently distorted, is known as bet spring. The two important types of springs are1. Leaf springs2. Helical springs

TABULATION:S. NoLoadDeflection reading (mm)Actual deflection (mm)Maximum shear stress induced (N/ mm)

KgN

Leaf springs which consist of a number of parallel strips of a metal having different lengths and same width, placed one over the other. These springs are used to absorb shocks in railway wagons, coaches and road vehicles (such as cars, Lorries etc.). Helical springs are the thick springs wires coiled into a helix. They are two types:1. Close coiled helical springs2. Open coiled helical springsIn close coiled helical springs, helix angle is very small or in other words the pitch between two adjacent turns is small.An open-coiled helical spring is a compression spring, that offers resistance to a compressive force applied axially. Compression springs are usually coiled as a constant-diameter cylinder.PROCEDURE:1. By using the micrometer measure the diameter of the wire of the spring2. By using the vernier caliper measure the diameter of the spring coil 3. Count the number of turns4. insert the spring testing machine and load the spring by a suitable weight and note the corresponding axial deflection in tension or compression5. Increase the load and take the corresponding axial deflection readings6. Plot a curve between load and deflection. Find the slope of the curve, which gives the stiffness of the spring.

CALCULATION:

RESULT:1. Stiffness, s = N/mm2. Modulus of rigidity, C = N/ mm3. Maximum Shear stress induced on the spring for a load of ( ), = N/ mm

REVIEW QUESTIONS:1. What is stiffness?2. What is the effect on stiffness, if a spring is cut into two half?3. What is the effect on net stiffness, if two springs are connected in parallel?4. What is the effect on net stiffness, if two springs are connected in series?5. What is solid length of the spring?6. How will you find work done on the spring?

TABLE:S.NoLoad(gm)Bending Moment (Nm) Bending stress (N/ mm)Theoretical value of strainExperimental value of strain

STRAIN MEASUREMENT

EX: NO: 8

DATE:

AIM:To measure the strain in the given cantilever beam using Rosette strain gauge and compare with theoretical value of the strain.

APPARATUS REQUIRED:Rosette strain GaugeFORMULA USED:1. Strain, e = 2. Bending stress, = N/ mm3. Moment of inertia, I = mm4Where,Y = = distance of the outer most layer form the neutral axis of the beam (mm)b = Width of the beam (mm)t = Thickness of the beam (mm)

THEORY:

The strain produced in a cantilever beam due to the application of load is determined by resistance type strain gauge fixed to the cantilever beam top surface. The change in resistance is proportional to the strain induced at a point where the gauge is fixed to the cantilever beam.

PROCEDURE:

The strain indicator of the available type is operated according to the operating details given by the instructions below one by one carefully1. Adjust the indicator till the display reads000.2. Apply load on the weight pan and note down the strain.3. Note strain for every 10kg weight addition.4. Calculate theoretical strain and compare with measured strain.

CALCULATION:

RESULT:

The experimental value can then be compared with the theoretical value.

REVIEW QUESTIONS:1. What is section modulus? Give the expression for it.2. Where the bending stress will be high? Give the explanation for it3. What is moment of inertia? What is the need to find moment of inertia?4. Is it possible to directly measure stress experientially? 5. What is the need to find strain experimentally?HARDNESS TEST AFTER QUENCHING

EX: NO: 9

DATE:

AIM:To check the effect of hardening- improvement in hardness of the given steel specimen after quenching.APPARATUS REQUIRED:1. Specimen2. Rockwell hardness testing machine3. Muffle furnace4. Quenching mediaTHEORY:Hardening refers to the heat treatment of steel, which increases the hardness by quenching. Hardening produces microstructures, which are predominantly martensic in nature. Hardening is used to harden steel to resist wear and enable it to cut other metals. Here the steel heated slowly in a furnace to temperature above the critical temperature (i.e., above the A3 line). The steel is cooled by quenching (in a wear or oil bath) to the room temperature. The cooling rate should be higher than the critical cooling rate in order to get the completely marten sic structure.Hardness of the specimen is tested using Rockwell hardness test. The hardness is correlated with depth of indentation. The hardness is inversely proportional to depth of indentation. A diamond indenter cone is used.PROCEDURE:1. Polish the unhardened specimen to be tasted.2. Place the specimen on the anvil of the machine.3. Keep in place the diamond indenter and apply a minor load by raising the level of anvil towards the bar.4. The pointer touches point3 called set point.5. Apply the major load by a hand lever for 6-8secs.6. Indentation is formed and pointer moves in anticlockwise direction.7. After load is released elastic recovery occurs in the deformed region and therefore depth is reduced. The pointer rotates in clockwise direction.8. Without removing the minor load the hardness number is noted.9. The minor load is removed.10. Pace the specimen in the muffle furnace and heat it till it becomes red hot at about 650C.Allow it at that temperature for 10-15 minutes.11. Cool the red-hot material by dipping it suddenly in the quenching media (Water or mineral oil).12. After cooling check the hardness of the hardened specimen using Rockwell hardness testing machine by repeating procedure1-9.

RESULT:1. The Rockwell Hardness number of the unhardened Specimen = HRC2. The Rockwell Hardness number of the Quenched Specimen = HRC

REVIEW QUESTIONS:1. What is hardening? 2. Name some components/ parts require hardening.3. What is the disadvantage of hardening? How can overcome that?4. What is the purpose of hardening?METALLURGICAL STUDY OF METALSEX: NO: 10

DATE:

AIM:To study microstructure of the metals before and after heat treatment.APPARATUS REQUIRED:1. Specimen2. Etchant3. Sand paper4. Metallurgical microscope5. CottonTHEORY:Studies of microstructure of metals are highly useful tools of metallurgist. Microstructure studies indicate grain size, phase present, condition of heat treat, inclusions and the like. If for example, if the metallurgist wishes to measure the grain size of the steel, he or she cuts a small piece from the part, mounts it in a potting compound, polishes it to a mirror finish, and then applies a chemical etching reagent. Grain boundaries will etch at a different rate than the grains, thus leaving the grains standing out, and they become visible with a reflected light microscope. Microstructure studies are also important tool in studying why a part failed in service.PROCEDURE:1. Prepare the specimen; apply the etching agent to the surface of the metal to be tested by metallurgical microscope.2. By the use of abrasive paper remove the thin layer of the metal surface to get clear original microscope.3. Place the specimen on the plate of microscope.4. Observe the image of the microscope by using correct magnifying issue.5. After heat treat (hardening and hardening & tempering), repeat the same procedure.6. Observe the difference between the microstructure before and after the heat treatment process.

RESULT:The microstructure of the metals before and after heat treatment has been studied.

REVIEW QUESTIONS:1. What is use of studying microstructure of the metals?2. What is grain?3. What is dislocation?4. What is effect of grain boundary on dislocation movement?5. Why fine grain metals are not always preferred for high temperature applications?16