PROPRIETIES AND TERMINOLOGY OF METALS

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PROPRIETIES AND TERMINOLOGY OF METALS

• AG TECH AND WELDING
• DEC 2002

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I CAN

• I can define the terms associated with metal and
  metal fabrication.
• I can explain metal classification.
• I can list the major characteristics of ferrous
  metal, nonferrous metal and alloys
• I can identify types of metals by the way of the
  spark test.
• I can identify the different ways marking and
  cutting metal.

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PROPRIETIES

• 1.      Solid at room temperature.
• Most metals are solid at room temperatures (one
  notable exception is mercury).
• Solid means having a definite shape and volume.
• 2.      Opaque
• Metal will not permit light to pass through it.
• Even very thin sheets of metal cannot be
  penetrated by ordinary light.
•  3.      Conductor of heat and electricity.
• All metals are conductors because they have
  electrons, which are free to move about.
• This property of metals is very important and
  widely used.
• (Gold, silver, aluminum and copper are very good
  conductors.)

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PROPRIETIES  

• 4.      Luster
• All metal seems to reflect light when polished.
•  5.      Crystalline structure
• Upon examination under a microscope, a metal is
  found to be made up of small grains.
• These grains (crystals) vary in shape and size.
• The arrangement of the atom (small particles
  within the grains) determine the shape of the
  crystalline structure.
•  6.      Expansion and contraction
• Metal expand when heated and contract when
  cooled. This is due to the spacing of the atoms
  within each grain of metal.
•  7.      Hardness
• This is the ability of a material to resist
  indentation, penetration, abrasion and
  scratching. Metals vary in hardness. Carbon
  content and application of heat will affect
  hardness.

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  PROPRIETIES

• 8.      Magnetism
• This is important property in metals.
• Metals that are attracted to a magnet are most of
  the ferrous metal, nickel and cobalt.
•  9.      Ductile
• Metals have the ability to become permanently
  deformed without cracking or failing.
• Many metals have this property such as aluminum
  and copper.
•  10.  Malleable
• The metal have the ability to be hammered or
  rolled into various shapes.
•  11.  High specific gravity
• Specific gravity is the ratio of the mass of a
  certain substance to that of an equal volume of
  water. In most cases metals have a higher
  specific gravity than water.
•  

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CHEMICAL PROPERTIES

• 1. Metal will combine with other elements such
  as oxygen, sulfur and the halogens.
• Iron has a special affinity for carbon.
•  2.      They are electropositive in character
  (due to the tendency to lose electrons)
•  3.      They are present as cations (positively
  charge, taken in) when their salts are dissolved
  in water.
•  4.      Whenever metals are fused together or by
  some means chemically combine at their point of
  contact by a process like welding, a sharing of
  electrons take place.
• The outer ring is not full in the electron, then
  atoms of two different elements, or two of the
  same come together to fill the outer ring.
• If the outer ring is fill, than there is no
  sharing of electrons like inert gases like argon
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TERMINOLOGY OF METALS

•  1.      Adhesion
• The sticking together of two unlike metals
  involving a
• mechanical bond.
• The mechanical bond involves the flowing of a
  metal in a
• liquid form into the pores of a metal in a solid
  form. Brazing
• and soldering are examples of adhesion.
• 2.      Alloy
• A mixture of two or more metals or metals and one
  or more non-metals.
• 3.      Annealing
• Softening metal and removing the brittleness.
  This is done by heating the metal to a cherry-red
  color and allowing it to cool slowly in
  vermiculite or dry hot sand.

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  TERMINOLOGY OF METALS

• 4.      Carbon
• An element (symbol C), nonmetal often mixed with
  iron.
•  5.      Casting
• In metalwork, pouring metal into a mold, so that
  after cooling it will be certain shape or form.
•  6.      Cementite
• The compound iron carbide (Fe3C) which is quite
  hard and brittle.
• It is iron with carbon dissolved in it.
• 7.      Ferrite
• Elemental iron which is usually very soft.
• It is only slightly harder that copper in a body
  centered cubic lattice composed of nine atoms.
• Examples are auto fenders and parts of soft
  drink cans.

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  TERMINOLOGY OF METALS

• 8.      Fusion
• The mixing of molten metals.
• 9.      Grains
• Most similar crystals closely packed together in
  standard symmetric pattern.
• 10.  Hardening
• Making steel harder.
• This is done by heating the medium or high carbon
  steel to a cheery red color and cooling it
  quickly in water. Hardened steel is not only
  extremely hard but also brittle. Hardening is
  the first step in tempering.
• 11.  Hardness-
• The ability of a metal to resist denting.

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TERMINOLOGY OF METALS

• 12.  Heat
• A type of energy.
• It is stored as molecular motion within a
  substance.
• Heat always mover from a substance of high heat
  content towards a substance of low heat content.
• 13.  Iron
• A crystalline metallic element. Symbol Fe.
• 14.  Lattice
• The fundamental geometric structure of the
  crystals. The three types of lattices found in
  iron are body-centered-cubic, face-centered-cubic
  and hexagonal. The body-centered-cubic is
  composed of 9 atoms. The face-centered-cubic is
  composed of 14 atoms. The hexagonal lattice is
  composed of 17 atoms.

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  TERMINOLOGY OF METALS

• 15.  Melting point
• The point at which a metal starts to change from
  solid to liquid.
• 16.  Tempering
• Obtaining the desired hardness and toughness in
  metal. The degree of hardness, brittleness or
  toughness is determine by the job expected of the
  steel.
•  17. Toughness
• The resistance to fracture after permanent
  deformation.

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CLASSIFICATION OF METALS

• Ferrous MetalMetals whose chief ingredient is
  iron.
• Non-Ferrous MetalMetals which have no iron and
  made up of single elements
• Ferrous Alloys-Metal made up largely of ferrous
  materials but have other elements in sufficient
  quantities to change the ferrous characteristics.
• Non-Ferrous AlloysMetals that are made up of two
  or more non-ferrous elements.

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Ferrous Metal

• Pig iron (Mine from soil)
• Cast iron
• Wrought Iron
• Steel
• low carbon steel
• medium carbon steel
• high carbon steel (Drill bits)

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Non-ferrous Metals

• Aluminum
• Copper
• Lead
• Magnesium
• Nickel
• Tin
• Tungsten
• Zinc
• Silver
• Gold

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Ferrous Alloy Metal

• Manganese steel
• Chrome steel
• Nickel steel
• Stainless steel
• Tungsten steel
• Molybdenum steel
• Vanadium steel
• Silicon steel
• Aluminum steel
• Phosphorus steel

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Non-Ferrous Alloy Metals

• Brass
• Bronze
• Solder
• Mixing of tin lead
• Melting point is lower.
• Pewter

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