SUBJECT: LEARNING OUTCOMES: Upon completion of the course, student will be able to demonstrate the knowledge and understanding of: • Properties and uses • Process • Basic metallurgy, metals and processes • Non-metallic materials • Materials under load • Vibration
• Explains in simple terms what influences the choice of material for a marine engineering component• Describes in simple terms what is meant by the following mechanical properties: elasticity, brittleness, hardness, strength, toughness, ductility, malleability, plasticity and machinability• Explains what is meant by low-; medium- and high-carbon steels• Compares the tensile strength, ductibility, and hardness of low-; medium- and high carbon steels• States the uses of low-; medium- and high carbon steels• Describes the properties of cast iron and gives examples of its uses• Defines an alloy• States the uses of aluminum, copper, zinc, lead, tin, and antimony• States the component metals of brass, bronze and white metal• States the uses of the above alloys• Explains why the above alloys are suitable for the uses of the above objectives
Physical Chemical Mechanical Properties of a metalElectrical Technological Thermal
Mechanical Properties of a Metal• Elasticity defined as the property of a metal by virtue of which it is able to retain its original shape and size after removal of the load.
2. Brittleness defined as the property of a metal by virtue of which it will fracture without any appreciable deformation.3. Hardness defined as the property of a metal by virtue of which it is able to resist abrasion, indentation and scratching by harder bodies.
4. Strength defined as the property of a metal by virtue of which it can withstand an external force or load without rupture. Types of strengths: elastic, plastic, tensile, compressive, shear, bending and torsion
5. Toughness defined as the property of a metal by virtue of which it can absorb maximum energy before fracture takes place.
6. Ductility defined as the property of a metal by virtue of which it can be drawn into wires or elongated before rupture takes place.
7. Malleability defined as the property of a metal by virtue of which it can be deformed into thin sheets by rolling or hammering without rupture. The following common metals have malleability in the decreasing order: Gold, silver, aluminum, copper, tin, platinum, lead, zinc, iron and nickel
8. Plasticity defined as the property of a metal by virtue of which a permanent deformation take place whenever it is subjected to the action of external forces.
8. Plasticity defined as the property of a metal by virtue of which a permanent deformation take place whenever it is subjected to the action of external forces.9. Machinability defined as the property of a metal by virtue of which indicates the case with which it can be cut or removed by cutting tools in various machining operations such as turning, drilling, boring, milling etc.
A vast range of metals exist and they fit in two categories,‘ferrous’ and ‘non-ferrous’ metals. These metals can be used tobuild/manufacture an equally large range of items. FERROUS METALS - Metals that contain iron NON-FERROUS METALS - Metals that do not contain iron
SOME FERROUS METALS AND PROPERTIES NAME ALLOY OF PROPERTIES USESMild Steel Carbon 0.1 - 0.3% Tough. High tensile strength. Can Most common Iron 99.9 - 99.7% be case hardened. Rusts very metal used in easily. school workshops. Used in general metal products and engineering.Carbon Steel Carbon 0.6 - 1.4% Tough. Can be hardened and Cutting tools Iron 99.4 - 98.6% tempered. such as drills.Stainless steel Iron, nickel and Tough, resistant to rust and stains. Cutlery, medical chromium. instruments.Cast iron Carbon 2 - 6% Strong but brittle. Compressive Castings, Iron 98 - 94% strength very high. manhole covers, engines.Wrought iron Almost 100% iron Fibrous, tough, ductile, resistant Ornamental gates to rusting. and railings. Not in much use today
SOME NON - FERROUS METALS AND PROPERTIES NAME COLOUR ALLOY OF; PROPERTIES USESAluminu Light grey Aluminum 95% Ductile, soft, malleable, Window frames,m Copper 4% machines well. Very aircraft, kitchen Manganese 1% light. ware.Copper Reddish Not an alloy Ductile, can be beaten Electrical brown into shape. Conducts wiring, tubing, electricity and heat. kettles, bowls, pipes.Brass Yellow Mixture of copper Hard. Casts and machines Parts for and zinc 65% - 35% well. Surface tarnishes. electrical most common ratio. Conducts electricity. fittings, ornaments.Silver Whitish grey Mainly silver but Ductile, Malleable, Jewellery, alloyed with copper solders, resists corrosion. solder, to give sterling silver. ornaments.Lead Bluish grey Not an alloy. Soft, heavy, ductile, loses Solders, pipes, its shape under pressure. batteries, roofing.
If you use metals as part of a practical project a knowledge of theshape or ‘section’ of lengths of metals is important. The diagramsbelow show examples of solid lengths and also tubes. When you ordermetals you need to describe the section you want. SECTIONS - SOLIDS AND TUBES ROUND SECTION SQUARE SECTION HEXAGONAL SECTION L-SECTION
The American Iron and Steel Institute (AISI) defines carbonsteel as follows:Steel is considered to be carbon steel when no minimum content isspecified or required for chromium, cobalt, columbium [niobium],molybdenum, nickel, titanium, tungsten, vanadium or zirconium,or any other element to be added to obtain a desired alloyingeffect;Classification:• Low-carbon steel, also known as mild steel. It as less than 0.30 percent carbon and generally used for industrial products: bolts, nuts, sheet, plate, tubes and machine components.
• Medium-carbon steel has 0.30 percent to 0.60 percent carbon. It is generally used in application requiring higher strength such as machinery, automotive and agricultural equipment parts, rail road equipment and parts for metalworking machinery.3. High-carbon steel has more than 0.60 percent carbon. It is generally used for parts requring strength, hardness and wear resistance such as cutting tools, cable, springs and cutlery.
Iron is one of the three magnetic elements. Cast iron is very brittlebut it has a greater resistance to corrosion than either pure iron orsteel. Cast iron is used for manhole covers on roads and pavementsand as engine blocks for petrol and diesel engines. Iron from the blast furnace contains about 5% carbon which comes from the coke in the furnace. It is cast into moulds called pigs and the iron is called cast iron or pig iron.
An alloy is a solid solution or homogeneous mixture of two or moreelements, at least one of which is a metal, which itself has metallicproperties. It usually has different properties from those of itscomponent elements. Alloys are used because they have specific properties or production characteristics that are more attractive than those of the pure, elemental metals. For example: • some alloys possess high strength • others have low melting points • others are refractory with high melting temperatures • some are especially resistant to corrosion • and others have desirable magnetic, thermal, or electrical properties These characteristics arise from both the internal and the electronic structure of the alloy. An alloy is usually harder than a pure metal and may have a much lower conductivity.
Aluminium is a silvery white and ductile member of the boron groupof chemical elements. It has the symbol Al.Aluminium is the most abundant metal and too reactive chemically tooccur in nature as the free metal. Instead, it is found combined in over270 different minerals. The chief source of aluminium is bauxite ore.Aluminium is remarkable for its ability to resist corrosion and its lowdensity. Structural components made from aluminium and its alloysare vital to the aerospace industry and very important in other areas oftransportation and building.Aluminium is the most widely used non-ferrous metal. Relativelypure aluminium is encountered only when corrosion resistance and/orworkability is more important than strength or hardness.
A thin layer of aluminium can be deposited onto a flat surface byphysical vapor deposition. When so deposited, a fresh, purealuminium film serves as a good reflector (approximately 92%) ofvisible light and an excellent reflector (as much as 98%) of mediumand far infrared.Pure aluminium has a low tensile strength, but when combined withthermo-mechanical processing, aluminium alloys display a markedimprovement in mechanical properties, especially when tempered.Aluminium alloys form vital components of aircraft and rockets as aresult of their high strength-to-weight ratio.Aluminium readily forms alloys with many elements such as copper,zinc, magnesium, manganese and silicon.
Copper is a chemical element with the symbol Cu. It is a ductilemetal with excellent electrical conductivity and is rather supple inits pure state and has a pinkish luster which is unusual for metalswhich are normally silvery white. It finds use as a heat conductor,an electrical conductor, as a building material, and as a constituentof various metal alloys.Copper is also an important ingredient of many useful alloys—combinations of metals, melted together. Brass is copper plus zinc. If it contains mostly copper, it is agolden yellow color; if it is mostly zinc, it is pale yellow or silvery.Brass is one of the most useful of all alloys; it can be cast or machinedinto everything from candle sticks to cheap, gold-imitating jewelry thatturns your skin green. Bronze is mainly copper plus tin
Uses of CopperCopper is vital for computers to work. Copper is used in building theintegrated circuits, chips, and the printed circuit boards of the computeralone. Copper is becoming more and more popular to use in the layersof the build-up of a chip. IBM announced a plan to use copper in itscomputer chip rather than aluminum. Doing so would make thecomputer to be cheaper and would allow it to make faster calculations.Copper is often used as a conductor of electricity. Almost all electricaldevices rely on copper wiring because copper is inexpensive andhighly conductive. The conductivity of copper is second only to silver.The reason why copper is a good conductor is because there are a lotof free electrons that can carry the flowing current efficiently. Thesefree electrons do not remain permanently associated with the copperatoms, instead they form an electron ‘cloud’ around the outside of theatom and are free to move through the solid quickly.
Copper is often used in currency. From 1909 to 1982, the Americanpenny was 95% copper. The other 5% was either zinc or bronzedepending on the year. The only exception was 1943. That year thepenny had zinc-plated steel in it. Unfortunately, the steel was magneticand kept getting stuck in vending machines. Also, the zinc corrodedeasily and was therefore often mistaken for a dime. In the early 1980’scopper increased in value. So in 1982, the United States switched thepenny’s core to zinc and coated it with copper.
Zinc is a metallic chemical element with the symbol Zn. Commerciallypure zinc is known as Special High Grade, often abbreviated SHG, andis 99.995% pure.Zinc is relatively non-reactive in air or water. Consequently, it isapplied in thin layers to iron and steel products that need to beprotected from rusting. This process is called galvanizing in which themetal is dipped in molten zinc.The second largest use of zinc is as an alloy and the remaining zincconsumption is for making paint, chemicals, agricultural applications,in the rubber industry, in TV screens, fluorescent lights and for dry cellbatteries.Zinc is also used as a main alloy for Brass.
(Option)One of the biggest uses of zinc is in making protective coatings forsteel. The development of the wide range of zinc coatings arose fromtwo happy accidents of chemistry, the relatively slow and predictablerate of atmospheric corrosion of zinc compared with steel, and therelative positions of zinc and iron in the electrochemical series. Zincwill corrode preferentially to give cathodic protection to iron whenboth are in contact in an aqueous medium. This is used to good effectto protect immersed structures such as ships’ hulls, drilling rigs andpipelines. It also means that any bare areas in a zinc coating on steel,caused by damage or operations such as cutting or drilling, are stillprotected by the surrounding zinc.Taken together, these two factors provide the basis of a uniquecorrosion protection system which uses some 4 million tonnes of zincannually to protect around 100 million tonnes of steel. This representsalmost half the total world consumption of zinc.
Tin is a chemical element with the symbol Sn. This silvery, malleablepoor metal that is not easily oxidized in air and resists corrosion, isfound in many alloys and is used to coat other metals to preventcorrosion.Tin is obtained chiefly from the mineral cassiterite, where it occurs asan oxide. It can be alloyed with copper to make bronze. Pewter alloyscontain from 85% up to 99% tin.Lead is a main group element with a symbol Pb. Lead is a soft,malleable poor metal, also considered to be one of the heavy metals.Lead has a bluish white color when freshly cut, but tarnishes to a dullgrayish color when it is exposed to air and is a shiny chrome silverwhen melted into a liquid.Lead is used in building construction, lead-acid batteries, bullets andshot, weights, and is part of solder, pewter, and fusible alloys.
Antimony is a chemical element with the symbol Sb. A metalloid,antimony has four allotropic forms. The stable form of antimony is ablue-white metalloid. Yellow and black antimony are unstable non-metals.Antimony is used in flame-proofing, paints, ceramics, enamels, a widevariety of alloys, electronics, and rubber.Brass is a metal alloy of Copper and Zinc, with copper contentranging from 58% to 95%. In addition to Zinc, the major alloyingelement, small additions (less than 5%) of other alloying elements areadded to modify the properties so that the resulting material is fit for agiven purpose. Typical applications: are nuts, bolts, screw threads.
Important Properties of Brass:• Excellent machinability• Good strength (250 – 500 MPa)• Corrosion resistance• Conductivity• Non sparking• Attractive color• Wear resistance• Readily recycled• Toughness• No loss of properties at temperature up to 200OC
Bronze is any of a broad range of copper alloys, usually with tin as themain additive, but sometimes with other elements such as phosphorus,manganese, aluminum, or silicon.The tin in bronze makes it more resistant to wear than unalloyedcopper. Bronzes today are usually stronger and more resistant tocorrosion than brass.The variations in bronze composition significantly affect itscharacteristics: Wearability, machinability, corrosion-resistance andductility for deep drawing are often considered.Bronze parts are typically used for bearings, clips, electricalconnectors and springs.
Commercial bronze, is 90-10, or 90% copper/10% tin. It is frequentlythe least expensive, most easily obtained grade of bronze.Aluminium bronze is a copper-aluminium alloy that may contain iron,nickel, and/or silicon for greater strength. It is used for tools and,because it will not spark when struck, for parts to be used aroundflammable materials. Aluminium bronze is frequently used for aircraftand automobile engine parts.Manganese bronze is actually a brass containing manganese. It is oftenused for ship propellers because it is strong and resists saltwatercorrosion.
The white metals are any of several light-colored alloys used as abase for plated silverware, ornaments or novelties, as well as anyof several lead-base or tin-base alloys used for things like bearings,jewellery, miniature figures, fusible plugs, some medals and metaltype.Some of the metals that make up a white metal alloy are antimony,tin, lead, cadmium, bismuth, and zinc. Not all of these metals arefound in all white metal alloys but are mixed to achieve a desiredgoal or need.As an example, a base metal for jewelry needs to be castable, polishable, have good flow characteristics, have the ability to castfine detail without an excessive amount of porosity and cast atbetween 230 °C and 300 °C