Metals

• 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
• 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
• 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.

  
• 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 like extrusion capability, corrosion resistance, and lightweight are considered)
• Aluminum Products


  • Aluminum Doors and Windows (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)
  • Ornamental Aluminum (rods, bars, pipes, railings, fittings, and special shapes manufactured as stock items for use in ornamental design of railings, grilles, screens, etc)
  • Aluminum Mesh and Wire Cloth (used for fencing, particularly chain link fencing and insect screening)
• Methods of Joining Metals

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

  • Steel Bars
  • Wire Fabric
  • Expanded Mesh
  • Laths
• Mechanical finishes on aluminum can be obtained by grinding, polishing, scratching, sandblasting, embossing, or other treatment of the surface to achieve desired effects
• 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
  • In structural applications only the properties of strength, expansion, resistance to corrosion, ductility, and workability are of interest to the architect
• High-strength low-alloy steels


  • A group of trade name steels with 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 of copper must be considered when used in architecture, as it will corrode other materials near the area of contact
  • Used extensively in the electrical field, from very fine wires to bus bars, and for roofing and flashing
• Tin


  Soft, ductile, malleable, bluish-white metal, normally covered with a thin film of stannic oxide which resists corrosion, 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
• Types of Metals


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


  • Is medium hard, bluish-white metal
  • Is characterized by brittleness and low strength
  • Is readily attacked by acids and alkalis
  • Is resistant to corrosion by water
  • On exposure to air, a film of zinc carbonate or oxide forms which protects tin from further oxidation
• Architectural uses of tin

  Bronzes, brasses, terneplate, mirrors, gilding, solders, hardware and fusible alloys
• Zinc


  • The most important uses are as protective coatings (galvanizing) on iron and steel, as die-casting metal, and as an alloying element in brasses
• Galvanizing


  1. A protective coat of zinc is applied to steel and iron to protect them against corrosion

  2. If the iron or steel becomes exposed, galvanic reaction between the coating and the base metal causes the zinc to corrode and form compounds which cover and continue to protect the iron and steel for as long as any zinc remains
• Galvanized sheets become defaced and discolored when subjected to dampness and extremes of temperature
• If galvanized sheets are piled flat in the open or tightly bundled in a warehouse, the zinc coating can also be damaged by the consequent absence of oxygen and carbon dioxide between two sheets. This absence prevents the formation of a protective film of zinc carbonate; instead zinc hydroxide forms and destroys the galvanizing
• Brass


  • Fundamentally an alloy of copper and zinc with small quantities of other elements sometimes added to give special qualities
  • The copper-zinc proportions may vary from 95% copper and 5% zinc to 55% copper and 45% zinc
  • As a class, brass alloys are less hard and strong than steels (iron-base alloys) but are superior in workability and resistance to corrosion