7-performance and characteristics of metals

• Stock forms


  Generally, the more complex the stock form or the more material the stock form contains, the more expensive it is
• Sheet


  • Large flat sections of metal in varying thicknesses from less than 1 mm up to approximately 3 mm
• Plate


  • Generally thicker than 3 mm and narrower than sheet metals
• Bar


  • Solid form, flat bar, square bar, round bar or hexagonal bar
• Tube form


  • Hollow in cross-section and can be square, rectangular (also called box section), round or hexagonal
• Structural angular shapes


  • H beams, L beams angle, I beams tee bar and channel
• Metal is a naturally occurring material and is mined from the ground in the form of ore
• Approximately 25 per cent of the Earth's crust is made up of metal ores
• Bauxite


  The most common ore, aluminium is extracted from bauxite
• Raw metal extraction


  1. Crushing

  2. Smelting or heating

  3. Addition of chemicals

  4. Huge amounts of electrical energy
• Metals can easily be recycled (due to their low melt point)
• Raw metal and the ore from which it is extracted

  • Copper - Chalcopyrite
  • Aluminium - Bauxite
  • Tin - Cassiterite
  • Zinc - Zinc blende
• Main categories of metals

  • Ferrous metal: a metal containing mostly iron and carbon
  • Non-ferrous metal: a metal that does not contain inon
  • Alley: a metal made of two or more metals, or combining two or more elements, one of which must be a metal
• Classification of metals


  • Non-ferrous - Aluminium, Copper, Zinc, Silver, Gold, Titanium, Tin
  • Ferrous - Low carbon steel, Medium carbon steel, Cast iron
  • Ferrous alloys - Stainless steel, High speed steel (HSS), Die steel tool steel
  • Non-ferrous alloys - Bronze, Brass, Duralumin, Pewter
• aluminium

  • Lightweight, ductile, malleable, corrosion resistant, electrical and thermal conductor, can be metal inert gas (MIG) and tungsten inert gas (TIG) heat welded, uses: drinks can, window frames, saucepans, cooking utensils
• copper

  • Ductile, malleable, tough, corrosion resistant, good electrical and thermal conductor, can be soldered and brazed
• Tin


  • ductile, malleable, Low melting point, good corrosion resistance, uses: coatings for food cans
• Silver


  • Malleable, ductile, corrosion resistant, can be soldered, uses: jewellery, culterly
• Gold


  • Malleable, ductile, corrosion resistant, can be soldered, uses: jewellery, electronic components
• Titanium


  • Hard, similar strength to steels but more lightweight, high resistance to corrosion, uses: hip replacements, tooth implants, bicycles
• Zinc


  • Ductile, malleable, low melting point, corrosion resistant, uses: galvanishing steel as protective coating for buckets, bins, farm gates
• Low carbon steel


  • Ductile, high tensile strength, tough, malleable, poor resistance to corrosion, uses:nuts, bolts, screws
• Medium carbon steel


  • Harder than low carbon steel but less ductile, malleable and tough, uses: springs, gardening tools
• Cast iron


  • Hard outer skin but brittle core, good under compression, uses:disc brakes, machine part
• Stainless steel


  • Tough, hard, corrosion resistant, uses: sinks, kitchen wear, culterly
• High speed steel (HSS)

  • Hard, tough, high level of resistance to frictional heat, uses: tools blades, drill bits
• Die steel (tool steel)

  • Hard, tough, uses: blanking punches and die
• Bronze


  • Tough, corrosion resistant, can be cast, uses: coins, statues
• Brass


  • Corrosion resistant, good electrical and thermal conductor, low melting point 930°C, casts well, uses: door furniture,boat fittings, ornaments
• Duralumin


  • Equivalent strength properties to mild steel but more light weight, ductie, becomes harder as it is worked, uses: vehicle parts, aircraft parts
• Pewter


  • Malleable, low melting point 170-230°C, casts well, uses: photo frames, sports trophies