Building Technology 1: Metals for Construction

Ferrous Metals

• Zinc (Zn) is a medium hard, bluish-white metal characterized by brittleness and low strength.
• Zinc is readily attacked by acids and alkalis but resistant to corrosion by water due to the formation of a film of zinc carbonate or oxide on exposure to air.
• Zinc is used for galvanizing (protective coating) iron and steel, and galvanized sheets become defaced and discolored when subjected to dampness and extremes of temperature.

Ferrous Metals

• Chromium (Cr) is a steel-white metal that takes a brilliant polish, is harder than cobalt or nickel, and is nonmagnetic at ordinary temperatures but becomes magnetic at 13 °F.
• Chromium does not tarnish in air, resists oxidizing agents, and is soluble in acids and strong alkalis.
• Chromium is used as an alloying ingredient in ferrous and nonferrous metallurgy, and chromium plating is used to give a thin, hard, bright, wear-resistant surface that sheds water when highly polished.

Ferrous Metals

• Tin (Sn) is a soft, ductile, malleable, bluish-white metal that resists corrosion by air, moisture, sulfur dioxide, and hydrogen sulfide due to a stannic oxide film.
• Tin takes a highly reflective polish and has the ability to wet other metals, with main uses in metallic form for protective coatings on stronger metals.
• Uses of tin include bronzes, brasses, terneplate, mirrors, gilding, solders, hardware, and fusible alloys.

Non-Ferrous Metals

• Aluminum is a soft, nonmagnetic silvery metal characterized by its light weight (1/3 that of iron, brass, or copper), low melting point, and high thermal and electrical conductivity.
• Aluminum readily combines with oxygen to form aluminum oxide, a transparent film that makes it corrosion-resistant, and is moderately high in coefficient of expansion.
• Aluminum is attacked by alkalis, hydrochloric acid, and other dilute acids, and is subject to galvanic action.

Non-Ferrous Metals

• Brass is an alloy of copper and zinc used for doors, windows, door and window frames, ornamental metalwork, and finish hardware.
• There are various types of brass, including red brass, aluminum brass, common brass, naval brass, and alpha-beta brass/Muntz metal.

Non-Ferrous Metals

• Bronze is an alloy of copper and tin used for casting, characterized by its corrosion resistance, density, and hardness.
• There are different types of bronze, including silicon bronze, gold bronze, phosphor bronze, aluminum bronze/Albronze, and manganese bronze.

Non-Ferrous Metals

• Nickel is an inert silvery metal and resistant to strong alkalis and most acids, resembling iron in strength and toughness and copper in its resistance to oxidation and corrosion.
• Nickel takes a high polish and can be hot and cold rolled, forged, bent, extruded, spun, punched, and drawn, and imparts its qualities to the resulting material when alloyed with other metals.

Metals for Concrete Reinforcement

• Steel bars are the most commonly used reinforcement, available in plain or deformed, and in various sizes and lengths.
• Wire fabric is made of cold-drawn steel wire and is widely used for the reinforcement of concrete slabs and floors.
• Expanded mesh is manufactured from solid steel sheets and is deformed into an open mesh-work in various shapes.

Metals for Concrete Reinforcement

• Laths are furnished either in flat or segmental sheets, pressed into a series of solid ribs, between which the metal is stamped, perforated, or deformed into an open mesh-work.
• Examples include Ribplex and Hyrib.

Metals for Concrete Reinforcement

• Storage and care of reinforcement involve storing in racks above the ground and away from moisture and vegetation, and keeping free from oil.
• Actual rust scales may indicate a reduction in the effective cross section of the bar, and all reinforcement should be kept free from oil.

Non-Ferrous Metals

• Copper is a ductile, malleable, nonmagnetic metal with a characteristic bright, reddish-brown color, high electrical and thermal conductivity, and corrosion resistance.
• Copper alloys have enough strength for minor structural work and are attacked by alkalis and many of the common acids.

Non-Ferrous Metals

• Lead is a blue-gray, soft, very heavy metal, extremely workable, and has good corrosion resistance, making it suitable for uses such as expansion shields for securing bolts, screws, and other accessories in masonry.

Non-Ferrous Metals

• Alclad refers to certain aluminum products with protective coatings applied primarily for corrosion resistance, and improves the appearance of the alloy.
• Duralumin is a light, strong alloy of aluminum, copper, magnesium, and manganese.

Non-Ferrous Metals

• Aluminum sheet and strip are used for roofing, flashing, gutter, etc., and can be extruded into various shapes.
• Corrugated aluminum is a rigidized sheet fabricated of special aluminum alloys specifically developed for this purpose.
• Aluminum doors and windows can be fabricated from extrusions and rolled shapes, and aluminum panels and sandwich panels are pre-fabricated units used for building exterior and interior partitions and dividers.### Metals Introduction
• Metals are elementary substances that are lustrous and crystalline in structure when solid.
• They are characterized by opacity, malleability, ductility, and conductivity.
• Metals are denser than other elemental substances and are good conductors of heat and electricity.
• Metals can be classified into two groups: ferrous metals and non-ferrous metals.

Ferrous Metals

• Ferrous metals contain iron as a principal element and are vulnerable to rust and corrosion.
• They are commonly used for bridges, skyscrapers, shipping containers, railways, large pipes, tunnels, and cars due to their inherent strength and weight.
• Ferrous metals are magnetic in nature and are useful in the manufacturing of electrical appliances like refrigerators.

Non-Ferrous Metals

• Non-ferrous metals contain little to no iron and are lightweight compared to ferrous metals.
• They are commonly used in lightweight construction, such as aircraft production and canning and bottle top production.
• Non-ferrous metals are also used for electrical and electronic applications due to their higher conductivity and malleability.

Heat Treating

• Heat treating is the most common treatment of metals.
• Grains in metals tend to grow larger as the metal is heated.
• There are three ways of heating metal: annealing, quenching, and tempering.

Metal Forming

• Metal forming is the process of mechanically shaping molten metal to form a desired product.
• Common methods of metal forming include casting, forging, rolling, drawing, extrusion, and stamping.

Metal Joining

• Metal joining involves joining two metals together using various techniques.
• Types of metal joining include soldering, brazing, welding, and rivets.

Ferrous Metals (Iron)

• Iron is a malleable, ductile, magnetic, silver-white metallic element.
• Properties of iron include:
  • Most magnetically permeable of the metals
  • Prone to rust and oxidation
  • Can be hardened by heating and sudden cooling
  • Brittle at low temperatures
  • Soft at red heat, weldable at white heat

Ferrous Metals (Iron Pig Iron)

• Pig iron is a crude iron that is drawn from a blast furnace and cast into pigs in preparation for conversion into cast iron, wrought iron, or steel.

Ferrous Metals (Cast Iron)

• Cast iron is a hard, brittle, non-malleable iron-based alloy containing 2.0-4.5% carbon and 0.5-3.0% silicon.
• It is used in architectural fields mainly for piping and fittings, ornamental ironwork, hardware, and miscellaneous casting.

Ferrous Metals (Wrought Iron)

• Wrought iron is a tough, malleable, relatively soft iron that is readily forged and welded, having a fibrous structure.
• It is used in architectural fields primarily in the form of genuine wrought iron pipe, chain, sheet, and ornamental ironwork.

Ferrous Metals (Steel)

• Steel is an iron-based alloy having a carbon content less than that of cast iron and more than that of wrought iron, usually not more than 2%.
• Properties of steel include:
  • Can be wrought, rolled, cast, and welded, but not extruded
  • Phosphorus, sulfur, oxygen, and nitrogen are present as impurities
  • Manganese, silicon, aluminum, copper, and nickel may be added to control the properties of steel

Ferrous Metals (Steel - Wrought Carbon Steel)

• Wrought carbon steel is used in structural steel, concrete reinforcement, sheet and strip, corrugated steel, and steel windows and doors hardware.
• Properties of wrought carbon steel include:
  • Can be hot-rolled or cold-rolled/formed
  • Used in fabricated form as decking galvanized sheet, expanded metal, panels, and sandwich panels
  • Used as a base metal for porcelain enamel

Ferrous Metals (Steel - Alloy Steel)

• Alloy steel is steel to which manganese, silicon, aluminum, titanium, and molybdenum have been added in sufficient quantity to produce properties unobtainable in carbon steels.
• Properties of alloy steel include:
  • Increased strength, hardness, ease and depth of hardenability, performance at high or low temperatures, electromagnetic properties, wear resistance, and electrical conductivity or resistivity.
  • Used in structural applications, the desired properties are strength, expansion, corrosion resistance, ductility, and workability.