Applied Science: Metals and Alloys PDF

## Applied Science 4-12 Metals and Alloys ### Mild Steel (0.05 - 0.3% carbon) * **Properties** * Good shock and impact resistant. * Difficult to harden and temper. * Low tensile strength. * **Applications** * Used for thin soft wires, ropes, bolts, rivets, nails etc. * Used for...

## Applied Science 4-12 Metals and Alloys ### Mild Steel (0.05 - 0.3% carbon) * **Properties** * Good shock and impact resistant. * Difficult to harden and temper. * Low tensile strength. * **Applications** * Used for thin soft wires, ropes, bolts, rivets, nails etc. * Used for chains, tubes, fan blades, seamless boiler plates etc. ### Medium Carbon Steel (0.3 - 0.6% carbon) * **Properties** * More hard, tough and less malleable than mild steels. * Can be hardened by heat treatment. * Easily weldable. * High tensile strength (50 kg/mm²) * Highly resistant to shock. * **Applications** * Widely used in railway engineering for rail roads, wheels, railway axles and fish plates. * Used in making machine and gun parts, springs and rotors and various shafts like armature and crank shafts. ### High Carbon Steels (0.6-1.5%) * **Properties** * Quite hard, tough, resistant to wear * Can produce a keen cutting edge. ### Non-Ferrous Alloys #### Brass (Copper Alloys) * **Properties** * High electrical conductivity. * Not weldable. * Hardness is improved by heat treatment. * Cannot be easily forged. * **Applications** * Working tools (chisel, hammers, punches, saws, drills etc.) * Used in making high tensile wires. * Cutting instruments (cutters, knives, blades and razors) #### Brasses (Copper and Zinc alloys) * **Properties** * Greater strength, durability and machinability than copper. * Lower melting point than copper and zinc. * Corrosion resistant and water resistance. * **Uses** * Making sheets, utensils, condenser tubes etc. **(i) Commercial Brass** Cu = 90%, Zn = 10% * **Properties** * Golden in color and stronger as well as harder than copper. * **Uses** * Architectural metal work, jewellery, forging rivets, hardware, screws etc. **(ii) Dutch Metal or low Brass** Cu = 80%, Zn = 20% * **Properties** * Golden color. * Suitable for all drawing and forming operations. * **Uses** * Cheap jewellery, musical instruments, battery caps, flexible hoses, name plates etc. **(iii) Cartridge Brass or spinning Brass** Cu = 70%, Zn = 30% * **Properties** * Strong, highly ductile in the annealed state. * Harder and stronger than copper. * Can be cold deformed by drawing, pressing and extrusion. * Hardens quickly. * **Uses** * Making tubes, sheets and cold press work. * Locomotive, condenser tubes, household articles and cartridge cases etc. **(iv) Muntz Metal** Cu = 60%, Zn = 40% * **Properties** * Stronger than 70/30 brass. * Suitable only for hot work. * **Uses** * Hot stampings, sheets etc. * Making hot rolled products, marine fittings, condenser tubes, springs, chains. **(v) Admiralty Brass** Cu = 70%, Zn = 29%, Sn = 1% * **Properties** * High corrosion and abrasion resistance. * Resistant to corrosion by seawater. * **Uses** * Propellers and marine works. **(vi) Naval Brass** Cu = 59%, Zn = 40%, Sn= 1% * **Properties** * High abrasion resistance and corrosion resistance to seawater. * **Uses** * Marine castings and condenser tubes. **(vii) German Silver or Nickel Silver** Cu = 62%, Zn = 18%, Ni = 20% * **Properties** * Very resistant to corrosion by seawater. * Strong, ductile, malleable. * Appears like silver. * **Uses** * Decorative articles, utensils, table wares, ornaments, cutlery, coinage, screw, bolts. #### Bronzes (Copper - Tin alloys) * **Properties** * Tough, strong, hard alloys. * Resistant to corrosion and wear. * Can be easily casted and machined. * **Uses** * Bells, coins, statues, utensils etc. **(i) Gun Metal** Cu = 85%, Sn = 5%, Zn = 5%, Pb = 5% * **Properties** * Hard, tough and strong. * Resistant to the force of explosion. * Resistant to corrosion by water and atmosphere. * **Uses** * Gun barrels. * Hydraulic and boiler fittings, foundryworks, heavy load bearing. **(ii) Aluminium Bronze** Cu = 90-93%, Al = 10-7% * **Properties** * Quite strong. * Readily fusible. * Good castings resistant to corrosion. * Good abrasion resistance. * Beautiful golden color. * **Uses** * Casting operations. * Bushes and bearings, jewellery, utensils, coins, photo frames, forged rods etc. **(iii) Phosphor Bronze** Cu = 96%, Sn = 3.75%, P = 0.25% * **Properties** * Hard, tough, ductile. * Low coefficient of friction. * Good casting property. * Resistant to sea water corrosion. * ** Uses** * Bearings, springs, gears, bushes, taps, turbine blades, spindles for valves, pumps, electric switches, radio aerial wires, suspension wires for moving coil galvanometersetc. **(iv) Nickelbronze** Cu = 90%, Ni = 9%, Fe = 1% * **Properties** * Hard. * High tensile strength. * Resistant to corrosion even than copper. * **Uses** * Rolling purposes, shafts, valves and general purpose, semi-hard bearings. **(v) Bell Metal** Cu = 80%, Sn = 20% * **Properties** * Hard, produce sound resistant to surface water, etc. * **Uses** * Bells and gangs, utensils etc. ### Solders * **Properties** * Low melting alloys of tin and lead. * Can be soft or hard depending on the percentage of tin and lead. * Becomes soft as the percentage of lead increases and that of tin decreases. * Solder containing equal parts of tin and lead is soft. * Melting point between 180° - 250° C. * Adhere to the metallic surface much better. * **Types** * **Soft Solders:** Pb 37-67%, Sn = 31-60%, Sb 0.12-0% * Have low melting points. * Used for soldering electrical connections, sealing for tin cans and joining lead pipes etc. * **Brazing Alloys:** Sn = 92%, Sb = 5.5% and Cu = 2.5% * Used for soldering of steel joints by the process of fusing. * **Tinmann's Solder:** Sn = 66% Pb = 34% * Used for joining articles of tin. ### Duralumin * **Composition:** Al = 95%, Cu = 4%, Mg = 0.5%, Mn = 0.5% * **Properties** * Light, tough, ductile, easily castable. * Corrosion resistant alloy. * Good conductor of heat and electricity. * Tensile strength can be increased by heat treatment up to 2000 kg/cm². * As strong as mild steel, though its density is 1/3rd that of steel. * Easily worked and have high machinability. * **Applications** * Aeroplanes, automobiles and locomotive parts. * All kinds of structural work. * Rivets, bars, body of vehicles, housing cases, sheets, tubes etc. * Cables, fluorescent tube caps, surgical instruments etc. * Ship building, pressings, etc. ### Wood's Metal * **Composition:** Bi = 50%, Pb = 25%, Sn = 12.5%, Cd=12.5% * **Properties** * Easily fusible. * Low melting point (71°C). * **Applications** * Safety plugs for pressure cookers, boilers, fire alarms, automatic water sprinklers etc. * Taking impressions of coins and medals. * Soft solder for joining two metallic parts. * Die mountings and fillers for tube bendings. * Electric fuses. * Casting for dental work. * Seals and gas tight joints in glass apparatus.