Metal notes

METALMetal is an element, compound or alloy that is a good conductor of both electricity and heat.Metal crystal structure and specific metal properties are determined by holding together the atoms of a metal

Metals in building construction are classified in two parts.

1. Ferrous Iron Steel Pig iron Cast ironWrought

iron

1. Non-Ferrous Copper & Alloys

Aluminium Zinc Tin Lead Cobalt Nickel

NATURE AND PROPERTIES OF METALS•Brittle material :- easily breaks into pieces or can be easily reduced to powder form.•Ductile material :- can be drawn into wires •Hard material :- can not be cut by a sharp tool•Malleable material :- can be beaten into sheets •Soft material :- can be easily cut by a sharp weapon •Tough material :- does not easily break under a hammer

Ferrous Metals•There are 4 types Pig IronCast IronWrought ironSteel

Metals Properties Uses

1. Pig Iron(contains 92% iron, upto 3.5% carbon &

other impurities )

•Can be hardened but not tempered•Can not be magnetized•Can not be welded•Does not rust•Difficult to bend•Hard and brittle•Neither ductile nor malleable•Melts easily •Possesses high compression strength but weak in tension

•Making steel…Modern steel mills and iron plants transfer the molten iron to a ladle for immediate use in the steel making furnaces or cast it into pigs on a pig-casting machine for reuse or resale.


2. Cast Iron •If placed in salt water, it becomes salt•Can be hardened by heating •Cannot be magnetized•Does not rust easily•Fusible•Hard but it is brittle•Isn’t ductile & cannot be adopted to absorb shocks•Melting temp is about 1250 deg Celsius•Shrinks on cooling•Structure is granular & crystalline•Lacks plasticity•Weak in tension & strong in compression•2 pieces of cast iron cannot be connected by the process

•Making cisterns, water pipes, gas pipes and sewers, sanitary fittings.•Making ornamental castings such as brackets, gates, lamp posts, spiral staircases etc.•Making parts of machinery •Manufacturing compression members like columns, bases o columns, etc.•Preparing agricultural implements•Preparing rail chairs, carriage wheels etc.


3. Wrought Iron •Becomes soft at white heat & can be easily welded.•Can be used to form temporary magnets.•Fuses with difficulty, therefore cannot be used for castings.•Ductile, malleable & tough.•Moderately elastic.•Unaffected by saline water•Resists corrosion•Melting point is 1500 deg Celsius•Clear bluish colour with a high silky luster and fibrous appearance.

•replaced at present to a very great extend by mild steel•used where a tough material is required.•Used for rivets, chains ornamental iron work, railway couplings, water and steam pipes, row material for manufacturing steel, bolts and nuts, horse shoe bars, handrails, straps for timber roof trusses, boiler tubes, roofing sheets, armatures, electro-magnets, etc

Non-Ferrous MetalsThere are 7 types1. Copper2. Aluminium3. Zinc4. Tin5. Lead6. Cobalt7. Nickel

Metal Properties Uses

1. Copper• Latin cuprum (Cu)

• ranks next to iron in importance and wide range of application

• Alloys: brass, bronze, cupro-nickel (copper nickel) alloys

Reddish-brown in colour Malleable ductile good heat and electrical

conductivity Turns green as it corrodes

•Electrical wires•Heating pipes•Roofing

2. Zinc bluish white in colour

corrosion resistant in air due to a thin oxide film forming on its surface

•For galvanizing(coating steel) to stop rusting

3. Tin• Latin stannum (Sn)

• tin based alloy with amounts of lead

•Silvery-white colour•Lustrous & soft•Malleable•Ductile•resistant to corrosion•Weak & combined with other metals

•coating for steel and sheet iron


4. Lead• Latin plumbum (Pb)

•can be cut white a knife.•makes impression on paper.•Lustrous & heavy metal•bluish-grey colour•possesses little tenacity.•very soft & plastic(can be easily moulded) at room temperature•Almost devoid of elasticity

•Making shots, bullets, alloys, storage cells•sanitary fittings, cisterns, water-proof and acid proof chambers•gas pipes, roof gutters• printing types •damp-proof courses of buildings, cable coverings• preparation of lead oxides for paints•plates for storage batteries, covering for electrical cables


5. Aluminium •Silver in colour•Very strong but light in weight•very good conductor of heat and electricity •non-magnetic substance•highly resistant to corrosion (oxide forms on the outside preventing corrosion)•Soft & malleable •Ductile

•reducing agent in the manufacture of steel•making automobile bodies, engine parts •casting of steel•manufacture of electrical conductors•manufacture of paints in powder form•Making drink cans, high tension wires

6. Cobalt •If cobalt is red hot, It can decompose steam.•Lustrous •white metal•malleable •Ductile

•preparation of special alloy steels, ceramic products, television articles, etc.•forms the basis of all blue colours used in glass and porcelain manufacture.


7. Nickel •If nickel is red hot, it can decompose steam. •grayish white in colour• lustrous•capable of taking a high polish and can easily be welded.•Hard & magnetic• malleable•It is not attacked by fused alkalis.•ranks below iron in electric conductivity.•resistance to corrosion is high.

•widely used as a coating for other metals •preparation of alloys like german silver, nickel, nickel steel etc.•Manufacture of chemical apparatus, electroplating parts of machines, domestic utensils etc.

Ferrous Metals Non-Ferrous Metals

1. Contains any amount of iron in its basic form. Does not contains any amount of iron in its basic form.

2. That’s why they possesses magnetic property and makes them prone to corrosion.

They do not possess magnetic property, but resist corrosion much better than ferrous metals.

3. They have a high tensile strength since they can carry a high amount of strain.

They have very low tensile strength.

4. They have the ability for oxidation, known as corrosion. Oxidation of ferrous metals forms as a reddish-brown deposit on the surface & is oxide of iron.

They have typically lighter weights, higher melting points & are basically resistant to corrosion.

5. Typically used when the magnetic attraction of iron may be a disadvantage. (used where strength is the primary focal point)

Ideal for electronic & electrical applications.

6. Eg., pig iron, steel, cast iron, etc. Eg., cobalt, aluminium, zinc, etc.

Steel•Steel is an alloy that consists mostly of iron and has a carbon content between 0.2% and 2.1% by mass

•There are 3 types of steels, namely :1. Cast Steel2. High-Speed Steel3. Stainless Steel

Steel Properties Uses

1. Stainless Steel• Also known as mild steel, is a

steel alloy with a minimum of 10.5 or 11% chromium content by

mass.

•can be magnetized permanently.•malleable •ductile.•not easily attacked by salty water.•rust easily and rapidly.•more elastic than wrought iron

•used for all types of structural works.


2. High Speed Steel •can be easily hardened and magnetized permanently.•has a granular structure.•Not easily attacked by salt water.•Has more elasticity than mild steel.•rust easily and rapidly.

•used for finest cutlery, edge tools and for an vibrations.

Cast Steel•Cast steel would be a steel that has been ‘cast’ into a particular shape.•It is a iron with less than 2% carbon that has been formed into a particular shape via a metal working process. It is the manufacturing process for a steel plate.•It is also used in many purposes, such as in tools & decorative hardware.

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Metal notes