STEEL PLATE AND SECTIONS

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

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

3. Evolution of ship hull materials • Evidence from ancient Egypt shows that the early Egyptians already knew how to assemble planks of wood into a watertight hull, using treenails to fasten them together, and pitch for caulking the seams. • Viking long ship's developed from an alternate tradition of clinker-built hulls fastened with leather thongs.

4. Evolution of ship hull materials • Iron was gradually adopted in ship construction, initially in small areas needing greater strength, then throughout, although initially copying wooden construction. • Isambard Brunel's Great Britain of 1843 was the first radical new design; built entirely of iron, using stringers for strength, inner and outer hulls, and bulkheads to form multiple watertight compartments. • Steel supplanted iron when it became readily available in the latter half of the 19th century. Wood continued to be favored for the decks, and is still the rule for modern cruise ships.

5. Modern ship hull

6. Requirements of ship hull material Factors affecting selection of ship hull material- • Availability and cost. • Uniformity • Ease of fabrication. • Ease of maintenance. • Strength vs. weight • Resistance to distortion under load.

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

8. Uniformity • The properties of the material must be uniform and dependable. • This is possible only when the material is subjected to careful quality control during its manufacture, and when the processes used in its manufacture are controllable and repeatable.

9. Ease of fabrication. • The ideal structural material must be easily and cheaply formed into different shapes (plates, rolled sections, castings, etc) and easily cut to size and joined together to built large ,sometimes complex structures. • The fabrication processes should not significantly alter the properties of the material ,so that its desirable properties are retained.

10. Ease of fabrication. • Joints between structural members should be as strong as the material being joined. • Since the development of welding processes, specially the electric arc welding that pre dominates in the ship fabrication today ,full strength joints are possible and normal.

11. Ease of maintenance • All materials are subject over a period of time to deterioration in service because of their exposure to liquids, gasses, chemicals, radiation or temperature changes. • The choice of material for particular engineering application is often dictated by their resistance to oxidation, corrosion, dissolution, thermal or radial damage in service.

12. Ease of maintenance • A measure of a materials effectiveness for ship construction is the ease with which it can be protected against corrosion and wastage by preventive maintenance and appropriate coatings. • The required frequency and expense of painting the structure is an important consideration in the choice of materials.

13. Strength vs. Weight • The strength of a material is an essential feature of any structural material . • A more important measure of a material’s structural efficiency is its strength: weight ratio. • A high strength: weight ratio is more desirable. • The lighter materials such as aluminum, titanium ,and magnesium have much higher strength :weight ratio than steel. • Unfortunately, all of these material are much more expensive than structural steel.

14. Resistance to distortion under load • A structural material should take large loads without permanent distortion, while remaining elastic (deformation under load are recovered when load is removed) over a large range of loading. • This is measured by modulus of elasticity of a material . • Of all of the common, readily available structural materials, steel has the highest modulus of elasticity.

15. MATERIAL TESTING Various tests carried out to determine qualities- • Tensile test. • Bend test. • Impact test.

16. Tensile Test • Method for determining behavior of materials under axial stretch loading. • Data from test are used to determine elastic limit, elongation, modulus of elasticity, proportional limit, reduction in area, tensile strength, yield point, yield strength and other tensile properties. • Tensile tests at elevated temperatures provide creep data. Procedures for tensile tests of metals are given in ASTM E-8.

17. Tensile Test • A tension-testing machine mechanically or hydraulically applies a tensile load to a specimen. The test establishes ultimate strength, yield strength, and ductility (elongation and reduction of area). • For the tensile test, a tension sample is expanded until fracture while the required tension force as well as the sample elongation is measured. • The tensile test serves the determination of characteristic material values like yield limit, tensile strength, fracture elongation, etc.

18. Tensile Test • Tensile stress (or tension) is the stress state leading to expansion (volume and/or length of a material tends to increase). • In the uni-axial manner of tension, tensile stress is induced by pulling forces across a bar, specimen etc. • Tensile stress is the opposite of compressive stress.

19. Bend Test • A test of ductility by bending or folding usually with steadily applied forces. • In some instances the test may involve blows to a specimen having a cross section that is essentially uniform over a length several times as great as the largest dimension of the cross section. • A test to determine ductility of flat rolled steel strip in which the strip is bent around its axis.

20. Bend Test • Method for measuring ductility of certain materials. • There are no standardized terms for reporting bend test results for broad classes of materials; rather, terms associated with bend tests apply to specific forms or types of materials. • For example, materials specifications sometimes require that a specimen be bent to a specified inside diameter (ASTM A-360, steel products). • A standard test done on reinforcing steel bars to check its amenability to bending in structural applications.

21. Impact Test • Response test where the broad frequency range produced by an impact is used as the stimulus. Sometimes referred to as a bump test. • A method for determining behavior of material subjected to shock loading in bending, tension, or torsion. • The various kinds of impact tests are Charpy Impact Test, Izod Impact Test, and Tension Impact Test.

22. Impact Test • Impact tests also are performed by subjecting specimens to multiple blows of increasing intensity, as in the drop ball impact test, and repeated blow impact test. • Impact resilience and scleroscope hardness are determined in nondestructive impact tests.

23. Charpy Impact Test • The test specimen is a 10mm square cross section,50mm in length. A vee-notch is cut in the centre of one face. The specimen is mounted horizontally with the notch axis vertical. • Test involves specimen being struck opposite the notch and fractured. A striker or hammer at the end of a swinging pendulum provides the blow which breaks the specimen. • The energy absorbed by the material in fracturing is measured by the machine.

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

25. Izod Impact Test • An impact strength test that gives a measure of toughness, the ability of a plastics material to resist breakage by flexural shock. • A destructive test designed to determine the resistance of a plastic to the impact of a suddenly applied force.

26. Tension Impact Test • Method for determining energy required to fracture a specimen under shock tensile loading .