building tech prefi

• Types of Metals


  • Aluminum
  • Iron
  • Steel
  • Copper
  • Tin
  • Zinc
  • Brass
  • Bronze
  • Chromium
  • Nickel
  • Lead
• Aluminum


  A soft, nonmagnetic silvery metal characterized by its light weight (1/3 that of iron, brass or copper), low melting point, high thermal and electrical conductivity (surpassed only by silver and copper), and moderately high coefficient of expansion

  
• Aluminum


  • Readily combines with oxygen to form aluminum oxide, a transparent film that makes it corrosion resistant
  • Readily attacked by alkalis, hydrochloric acid and other dilute acids
  • Subject to galvanic action and should therefore be electrically insulated from direct contact with metals other than zinc, cadmium, magnesium and nonmagnetic stainless steel
  • Easily worked: can be hot or cold rolled, extruded, forged, pressed, drawn, molded, stamped, bent and shaped
  • Can be riveted, bolted, welded, brazed and soldered
• Fabricated forms of aluminum used in architectural work

  • Rod
  • Bar
  • Extrusion
  • Casting
  • Sheet
  • Strip
• Extrusion


  The process of shaping material by forcing it to flow through a shaped opening in a die. Extruded material emerges as an elongated piece with the same profile as the die opening.
• Aluminum products are not fabricated from pure aluminum but in alloy combination with iron, silicon, copper, manganese, magnesium, zinc, chromium and nickel in small quantities to give strength and other desirable characteristics but often reduces its corrosion resistance

  
• Alclad


  A term applied to certain aluminum products, refers to the protective coating (cladding) applied, primarily for corrosion resistance, to thin sheets of an alloy whose corrosion resistance has been decreased by the constituents added to give strength and other characteristics. Cladding improves the appearance of the alloy. This thin, integral cladding usually consists of pure aluminum, magnesium silicide, or zinc alloys, with or without manganese.

  
• Types of Aluminum


  • Aluminum Sheet and Strip (used for roofing, flashing, gutter, etc)
  • Aluminum Foil (rolled to a thickness of 0.005", used mainly for thermal insulation and vapor barriers)
  • Corrugated Aluminum (rigidized sheet fabricated of special aluminum alloys specifically developed for this purpose, usually consists of an aluminum alloy core of one type clad with another, highly corrosion-resistant aluminum)
  • Structural Aluminum (when used as a structural material, important factors are that it can be extruded, very corrosion resistant alloys are available, and it is a lightweight material)

  
• Aluminum doors and windows are generally fabricated from extrusions and rolled shapes
• Aluminum Panels and Sandwich Panels

  Pre-fabricated units, generally manufactured using dimensions of modular and non-modular window-width for building exterior, and in 600mm, 900mm, and 1200mm widths for interior partitions and dividers. Panels for the exterior of buildings primarily consist of an aluminum exterior facing which may be an aluminum casting or an extrusion or sheet material which has been pressed, stamped or formed into specially designed shapes.
• Sandwich Panel


  A system of construction called skin construction, where a cellular core of aluminum or other material has a skin of aluminum applied and bonded to both sides, thereby forming a unified whole in which all the components work as one.
• Ornamental aluminum products


  • Rods
  • Bars
  • Pipes
  • Railings
  • Fittings
  • Special shapes

  
• Other aluminum products


  • Mesh
  • Wire Cloth (used for fencing, particularly chain link fencing and insect screening)
• Mechanical finishes on aluminum are obtained by grinding, polishing, scratching, sandblasting, embossing, or other treatment of the surface to achieve the desired appearance
• Methods of Joining Metals

  • Soldering
  • Brazing
  • Welding
  • Rivets
• Metals for Concrete Reinforcement

  • Steel Bars
  • Wire Fabric
  • Expanded Mesh
  • Laths
• Storage and care for metal reinforcement is important
• Types of Metals


  • Aluminum
  • Iron
  • Steel
  • Copper
  • Tin
  • Zinc
  • Brass
  • Bronze
  • Chromium
  • Nickel
  • Lead
• Steel


  Alloys of iron and carbon which do not contain more than 2% carbon and which are made in malleable or ingot form
• Steel


  • Iron is always in excess of 95%
  • Phosphorus, sulfur, oxygen and nitrogen are present as impurities
  • Manganese, silicon, aluminum, copper and nickel may also be present either as residual impurities or as elements deliberately added in small quantities to control the properties of the steel
  • Can be wrought, rolled, cast, and welded, but not extruded
• Structural steel


  Medium carbon steel with its carbon content controlled to give both the strength and ductility necessary for its use
• Cast iron


  Iron-carbon alloy that contains more than 1.7% carbon, poured while molten into forms
• Cast iron


  • Too hard and brittle to be shaped by hammering, rolling, or pressing
  • Used for piping and fittings, ornamental ironwork, hardware, plumbing fixtures, brackets, stairs, manhole covers, gratings
• Wrought iron


  Almost pure iron with less than 0.1% carbon, usually not more than 0.05%, contains 2.5% of slag (iron silicate) in purely physical association, not alloyed
• Wrought iron


  • Soft, malleable, tough, fatigue-resistant, and resistant to progressive corrosion
  • Good machinability, can be forged, bent, rolled, drawn, and spun, can be welded
• Wrought iron is now used in the architectural field primarily in the form of genuine wrought iron pipe, chain, sheet, and ornamental ironwork
• Carbon steel


  Can be wrought, rolled, cast, and welded, but not extruded
• Structural steel


  • Medium carbon steel with its carbon content controlled to give both the strength and ductility necessary for its use
  • Available in angles, channels, I-beams, H columns, T shapes, Z shapes, plates, round pipe columns, sheet piling, open web joists, and light steel framing shapes
• Wrought Carbon Steels


  • Sheet and strip
  • Corrugated steel
  • Steel Mesh and Wire Cloth
  • Steel Windows and Doors
  • Hardware such as nails, screws, rivets, etc
• Alloy Steels


  • Steels to which manganese, silicon, aluminum, titanium, and molybdenum have been added in sufficient quantity to produce properties unobtainable in carbon steels in cast, rolled or heat-treated form
  • The alloying elements are added to increase strength, hardness, ease and depth of hardenability, performance at high or low temperatures, electromagnetic properties, wear resistance, electrical conductivity or resistivity
• High-strength low-alloy steels


  • Improved mechanical properties and resistance to atmospheric corrosion, used as reinforcing for pre-stressed concrete, high strength bolts, special structural steels and cables for elevators, etc.
• Stainless steels


  • Highly alloyed steels that contain more than 10% chromium, characterized by their resistance to heat, oxidation and corrosion, used where corrosion resistance, durability, and minimum of maintenance is necessary principally for exterior and interior wall finishes, doors, windows, trims, railings, signs and letters, appliances, etc.
• Copper


  Ductile, malleable, nonmagnetic metal with a characteristic bright, reddish brown color, has the highest electrical and thermal conductivity of any substances except silver, useful alloys have enough strength for minor structural work, easily worked, attacked by alkalis and many of the common acids
• Copper


  • Highly resistant to corrosion by air and salt water, forms a surface layer of an insoluble green salt which retards further corrosion (patina)
  • Can be cast, drawn, extruded, hot and cold worked, spun, hammered, punched, welded, brazed, and soldered
  • Galvanic action must be considered when used with other construction materials, will corrode these materials near the area of contact
  • Used extensively in electrical field, from very fine wires to bus bars, sheet and strip used for roofing and flashing
• Tin


  Soft, ductile, malleable, bluish-white metal, normally covered with a thin film of stannic oxide which resists corrosion by air, moisture, sulfur dioxide, hydrogen sulfide, takes a highly reflective polish and has the ability to wet other metals
• Tin


  • Main use is in metallic form of either pure tin or tin-containing alloys for protective coatings on stronger metals, architectural uses include bronzes, brasses, terneplate, mirrors, gilding, solders, hardware and fusible alloys
• Zinc


  Medium hard, bluish-white metal, characterized by brittleness and low strength, readily attacked by acids and alkalis, resistant to corrosion by water, forms a protective film of zinc carbonate or oxide on exposure to air
• Zinc


  • Most important uses are as protective coatings (galvanizing) on iron and steel, as die-casting metal, and as an alloying element in brasses
• Architectural uses of tin

  • Bronzes
  • Brasses
  • Terneplate
  • Mirrors
  • Gilding
  • Solders
  • Hardware
  • Fusible alloys
• Tin


  Medium hard, bluish-white metal, characterized by brittleness and low strength, readily attacked by acids and alkalis, resistant to corrosion by water