STEELSTEEL PLATEPLATE ANDAND SECTIONSSECTIONS

GROUP B-GROUP B- MAHADIK ROHAN.MAHADIK ROHAN. KULHARI SUNDEEP.KULHARI SUNDEEP. BHULLAR KUNWAR PUNEET SINGH.BHULLAR KUNWAR PUNEET SINGH. KRISHNAN PRASHANT.KRISHNAN PRASHANT.

What are the requirements of a What are the requirements of a good ship hull material and what good ship hull material and what are the material tests carried out are the material tests carried out to determine their qualities.to determine their qualities.

Evolution of ship hull Evolution of ship hull materials materials Evidence from ancient Evidence from ancient

Egypt shows that the Egypt shows that the early Egyptians already early Egyptians already knew how to assemble knew how to assemble planks of wood into a planks of wood into a watertight hull, using watertight hull, using treenails to fasten them treenails to fasten them together, and pitch for together, and pitch for caulking the seams. caulking the seams.

Viking long ship's Viking long ship's developed from an developed from an alternate tradition of alternate tradition of clinker-built hulls clinker-built hulls fastened with leather fastened with leather thongs. thongs.

Iron was gradually adopted in ship construction, Iron was gradually adopted in ship construction, initially in small areas needing greater strength, initially in small areas needing greater strength, then throughout, although initially copying then throughout, although initially copying wooden construction. wooden construction.

Isambard Brunel's Isambard Brunel's Great BritainGreat Britain of 1843 was the of 1843 was the first radical new design; built entirely of iron, first radical new design; built entirely of iron, using stringers for strength, inner and outer hulls, using stringers for strength, inner and outer hulls, and bulkheads to form multiple watertight and bulkheads to form multiple watertight compartments. compartments.

Steel supplanted iron when it became readily Steel supplanted iron when it became readily available in the latter half of the 19th century. available in the latter half of the 19th century. Wood continued to be favored for the decks, and is Wood continued to be favored for the decks, and is still the rule for modern cruise ships. still the rule for modern cruise ships.

Evolution of ship hull materialsEvolution of ship hull materials

Modern ship hull

Requirements of ship hull Requirements of ship hull materialmaterial

Factors affecting selection of ship hull material-Factors affecting selection of ship hull material- Availability and cost.Availability and cost. UniformityUniformity Ease of fabrication.Ease of fabrication. Ease of maintenance.Ease of maintenance. Strength vs. weightStrength vs. weight Resistance to distortion under load.Resistance to distortion under load.

Availability and cost.Availability and cost.

The material must be readily available and The material must be readily available and relatively inexpensive, as great quantities are relatively inexpensive, as great quantities are required in construction of large ships.required in construction of large ships.

UniformityUniformity

The properties of the material must be uniform The properties of the material must be uniform and dependable.and dependable.

This is possible only when the material is This is possible only when the material is subjected to careful quality control during its subjected to careful quality control during its manufacture, and when the processes used in its manufacture, and when the processes used in its manufacture are controllable and repeatable.manufacture are controllable and repeatable.

Ease of fabrication.Ease of fabrication. The ideal structural material The ideal structural material

must be easily and cheaply must be easily and cheaply formed into different shapes formed into different shapes (plates, rolled sections, (plates, rolled sections, castings, etc) and easily cut to castings, etc) and easily cut to size and joined together to size and joined together to built large ,sometimes built large ,sometimes complex structures.complex structures.

The fabrication processes The fabrication processes should not significantly alter should not significantly alter the properties of the the properties of the material ,so that its desirable material ,so that its desirable properties are retained.properties are retained.

Joints between structural Joints between structural members should be as members should be as strong as the material strong as the material being joined. being joined.

Since the development of Since the development of welding processes, welding processes, specially the electric arc specially the electric arc welding that pre welding that pre dominates in the ship dominates in the ship fabrication today ,full fabrication today ,full strength joints are strength joints are possible and normal. possible and normal.

Ease of fabrication.Ease of fabrication.

Ease of maintenanceEase of maintenance

All materials are subject over a period of time to All materials are subject over a period of time to deterioration in service because of their deterioration in service because of their exposure to liquids, gasses, chemicals, radiation exposure to liquids, gasses, chemicals, radiation or temperature changes.or temperature changes.

The choice of material for particular engineering The choice of material for particular engineering application is often dictated by their resistance application is often dictated by their resistance to oxidation, corrosion, dissolution, thermal or to oxidation, corrosion, dissolution, thermal or radial damage in service. radial damage in service.

A measure of a materials effectiveness for ship A measure of a materials effectiveness for ship construction is the ease with which it can be construction is the ease with which it can be protected against corrosion and wastage by protected against corrosion and wastage by preventive maintenance and appropriate preventive maintenance and appropriate coatings.coatings.

The required frequency and expense of painting The required frequency and expense of painting the structure is an important consideration in the the structure is an important consideration in the choice of materials.choice of materials.

Ease of maintenanceEase of maintenance

Strength vs. WeightStrength vs. Weight The strength of a material is an essential feature The strength of a material is an essential feature

of any structural material .of any structural material . A more important measure of a material’s A more important measure of a material’s

structural efficiency is its strength: weight ratio.structural efficiency is its strength: weight ratio. A high strength: weight ratio is more desirable.A high strength: weight ratio is more desirable. The lighter materials such as aluminum, titanium The lighter materials such as aluminum, titanium

,and magnesium have much higher ,and magnesium have much higher strength :weight ratio than steel.strength :weight ratio than steel.

Unfortunately, all of these material are much Unfortunately, all of these material are much more expensive than structural steel.more expensive than structural steel.

Resistance to distortion Resistance to distortion under loadunder load

A structural material should take large loads A structural material should take large loads without permanent distortion, while remaining without permanent distortion, while remaining elastic (deformation under load are recovered elastic (deformation under load are recovered when load is removed) over a large range of when load is removed) over a large range of loading.loading.

This is measured by This is measured by modulus of elasticity modulus of elasticity of a of a material .material .

Of all of the common, readily available structural Of all of the common, readily available structural materials, steel has the highest modulus of materials, steel has the highest modulus of elasticity.elasticity.

MATERIAL TESTINGMATERIAL TESTING

Various tests carried out to determine qualities-Various tests carried out to determine qualities-

Tensile test.Tensile test. Bend test.Bend test. Impact test.Impact test.

Tensile TestTensile Test Method for determining behavior of materials Method for determining behavior of materials

under axial stretch loading. under axial stretch loading.

Data from test are used to determine elastic Data from test are used to determine elastic limit, elongation, modulus of elasticity, limit, elongation, modulus of elasticity, proportional limit, reduction in area, tensile proportional limit, reduction in area, tensile strength, yield point, yield strength and other strength, yield point, yield strength and other tensile properties. tensile properties.

Tensile tests at elevated temperatures provide Tensile tests at elevated temperatures provide creep data. Procedures for tensile tests of metals creep data. Procedures for tensile tests of metals are given in ASTM E-8. are given in ASTM E-8.

A tension-testing machine mechanically or A tension-testing machine mechanically or hydraulically applies a tensile load to a specimen. The hydraulically applies a tensile load to a specimen. The test establishes ultimate strength, yield strength, and test establishes ultimate strength, yield strength, and ductility (elongation and reduction of area).ductility (elongation and reduction of area).

For the tensile test, a tension sample is expanded until For the tensile test, a tension sample is expanded until fracture while the required tension force as well as the fracture while the required tension force as well as the sample elongation is measured. sample elongation is measured.

The tensile test serves the determination of The tensile test serves the determination of characteristic material values like yield limit, tensile characteristic material values like yield limit, tensile strength, fracture elongation, etc.strength, fracture elongation, etc.

Tensile TestTensile Test

Tensile stress (or tension) is the stress state Tensile stress (or tension) is the stress state leading to expansion (volume and/or length of a leading to expansion (volume and/or length of a material tends to increase). material tends to increase).

In the uni-axial manner of tension, tensile stress In the uni-axial manner of tension, tensile stress is induced by pulling forces across a bar, is induced by pulling forces across a bar, specimen etc.specimen etc.

Tensile stress is the opposite of compressive Tensile stress is the opposite of compressive

stress.stress.

Tensile TestTensile Test

Bend TestBend Test A test of ductility by bending or folding usually A test of ductility by bending or folding usually

with steadily applied forces.with steadily applied forces.

In some instances the test may involve blows to a In some instances the test may involve blows to a

specimen having a cross section that is specimen having a cross section that is essentially uniform over a length several times as essentially uniform over a length several times as great as the largest dimension of the cross great as the largest dimension of the cross section.section.

A test to determine ductility of flat rolled steel A test to determine ductility of flat rolled steel strip in which the strip is bent around its axis.strip in which the strip is bent around its axis.

Method for measuring ductility of certain materials. Method for measuring ductility of certain materials. There are no standardized terms for reporting bend There are no standardized terms for reporting bend

test results for broad classes of materials; rather, test results for broad classes of materials; rather, terms associated with bend tests apply to specific terms associated with bend tests apply to specific forms or types of materials.forms or types of materials.

For example, materials specifications sometimes For example, materials specifications sometimes require that a specimen be bent to a specified require that a specimen be bent to a specified inside diameter (ASTM A-360, steel products). inside diameter (ASTM A-360, steel products).

A standard test done on reinforcing steel bars to A standard test done on reinforcing steel bars to check its amenability to bending in structural check its amenability to bending in structural applications.applications.

Bend TestBend Test

Impact TestImpact Test Response test where the broad frequency range Response test where the broad frequency range

produced by an impact is used as the stimulus. produced by an impact is used as the stimulus. Sometimes referred to as a bump test. Sometimes referred to as a bump test.

A method for determining behavior of material A method for determining behavior of material subjected to shock loading in bending, tension, subjected to shock loading in bending, tension, or torsion.or torsion.

The various kinds of impact tests are Charpy The various kinds of impact tests are Charpy Impact Test, Izod Impact Test, and Tension Impact Test, Izod Impact Test, and Tension Impact Test. Impact Test.

Impact tests also are performed by subjecting Impact tests also are performed by subjecting specimens to multiple blows of increasing specimens to multiple blows of increasing intensity, as in the drop ball impact test, and intensity, as in the drop ball impact test, and repeated blow impact test.repeated blow impact test.

Impact resilience and scleroscope hardness are Impact resilience and scleroscope hardness are determined in nondestructive impact tests.determined in nondestructive impact tests.

Impact TestImpact Test

Charpy Impact TestCharpy Impact Test The test specimen is a 10mm square cross The test specimen is a 10mm square cross

section,50mm in length. A vee-notch is cut in the section,50mm in length. A vee-notch is cut in the centre of one face. The specimen is mounted centre of one face. The specimen is mounted horizontally with the notch axis vertical.horizontally with the notch axis vertical.

Test involves specimen being struck opposite the Test involves specimen being struck opposite the notch and fractured. A striker or hammer at the notch and fractured. A striker or hammer at the end of a swinging pendulum provides the blow end of a swinging pendulum provides the blow which breaks the specimen.which breaks the specimen.

The energy absorbed by the material in The energy absorbed by the material in fracturing is measured by the machine.fracturing is measured by the machine.

This test is particularly important for materials This test is particularly important for materials to be used in low temperatures. The impact test to be used in low temperatures. The impact test in effect measures a material’s resistance to in effect measures a material’s resistance to fracture when shock loaded.fracture when shock loaded.

Charpy Impact TestCharpy Impact Test

Izod Impact TestIzod Impact Test An impact strength test that gives a measure of An impact strength test that gives a measure of

toughness, the ability of a plastics material to toughness, the ability of a plastics material to resist breakage by flexural shock. resist breakage by flexural shock.

A destructive test designed to determine the A destructive test designed to determine the resistance of a plastic to the impact of a suddenly resistance of a plastic to the impact of a suddenly applied force.applied force.

Tension Impact TestTension Impact Test Method for determining energy required to Method for determining energy required to

fracture a specimen under shock tensile loading .fracture a specimen under shock tensile loading .