Metals
  • Properties of Metal
    • Strength
      • Tensile Strength -Tension- ability to withstand tension
      • Yield Strength - Ability to resist deformation
      • Bearing Strength - Ability of a joint to withstand any form crushing or excessive compressive distortion
    • Hardness - Ability to resist cutting, penetration, or abrasion
    • Malleability - Ability to be bent, formed, or shaped without cracking or breaking
    • Ductility - Ability of metal to be drawn into wire stock, extrusion, or rods
    • Brittleness - A material's tendency to break or shatter when exposed to stress.
      • opposite of ductility and Malleability
    • Conductivity - Property which enables a metal to carry heat or electricity
      • Thermally Conductive - Ability to of a metal to transmit heat
      • Heat Exchange - Ability to conduct heat away
      • Electrical Conductivity - The measure of a material's ability to allow electron flow.
    • Thermal Expansion - Property of metal to expand when heated and shrink when cooled
      • Coefficient of Expansion - Amount of expansion and contraction which is predictable at specific temperatures
    • Elasticity - A metals tendency to return to its original shape after normal stretching and bending
      • Elastic Limit - The point beyond which the metal does not return to its original shape after a deforming force is removed.
    • Toughness - A materials ability to resist tearing or breaking when it is bent or stretched.
    • Fusibility - The ability of a metal to be joined by heating and melting
    • Density - Is the mass per unit volume
      • Aluminum has a density of 27g/cm cubed.
  • Metal Working Processes
    • Wrought - When metal is formed by physically working it into shape
    • Cast - Metal is formed by pouring molten metals into molds
    • Hot-Working - Process of forming metal at an elevated temperature when it is annealed, or in the soft condition
    • Rolling - Used to form large and heavy parts
    • Drop Forging - A hammering process where by a hot ingot is placed between a pair of formed dies in a machine called a drop hammer and a weight of several tons is dropped on the upper dies.
    • Hammering - A type of forging that is usually used on small parts because it requires a metal worker to physically hammer a piece of metal into its finished shape.
    • Cold-Working - Preformed well below a metal's critical temperature and ranges from the manual bending of sheet metal for skin repairs to drawing seamless tubing and wire.
    • Cold Rolling - Usually refers to the the rolling of metal at room temperature to its approximate size
    • Extrusion - Process of forming metal through a die which imparts a required cross-section to the metal.
  • Nonferrous Metals - Describes metals which have elements other than iron as their base.
    • Aluminum
    • Copper
    • Titanium
    • Magnesium
  • Aluminum Alloys
    • Alloyed - When one metal is mixed w/ other compatible metals
    • Alloying agents: (1)[0]{xx} (Alloying agent) [Alloy Modification, 1-9 indicates no. of controls over impurities] {in 1x its .00% above original 99% in 2x-8x identifies different alloys in the group}
      • Aluminum 1xxx
        • 99% pure aluminum and offers high corrosion resistance
      • Copper 2xxx
        • Provides great strength but susceptibility to intergranular corrosion when improperly heat treated.
      • Maganese 3xxx
        • Moderate strength and has good working conditions
      • Silicon 4xxx
        • Works well for working and brazing
      • Magnesium 5xxx
        • Good for welding and corrosion resistance but if heated or chilled it corrodes more readily
      • Magnesium and Silicon 6xxx
        • Is heat-treatable, has medium strength w/ good forming and corrosion resistance
      • Zinc 7xxx
        • very hard and difficult to bend
      • Others 8xxx
    • Clad Aluminum Alloy
      • Alclad - is a pure aluminum coating that is rolled on to the surface of heat-treated aluminum alloy which is 5% of the alloys thickness on each side.
  • Magnesium and Its Alloys - Used in castings and in its wrought form is available in sheets, bars, tubing, and extrusions
    • Obtained primarily obtained from electrolysis of sea water or brine from deep wells, and is highly susceptible to corrosion, and tends to crack.
      • To prevent corrosion the surface of the metal is treated with chemicals that form an oxide film to prevent oxygen from reaching the metal
      • It also burns readily in a dust or small particle form
        • If a fire occurs, extinguish it by smothering it with dry sand or some other dry material that excludes air from the metal and cools it surface.
    • Alloyed with :
      • Zinc - Z
      • Aluminum - A
      • Thorium - H
      • Zirconium - K
      • Manganese - M
    • Solution Heat treatment - Increases tensile strength, ductility, and resistance to shock.
      • Once its been Solution Heat Treated it can be Precipitation Heat Treatment
    • Precipitation Heat Treatment - Increases the metal's hardness and yield strength.
  • Titanium and Its Alloys - Light weight metals with very high strength.
    • Its 50% lighter than Stainless Steel and is approximately equal in strength to Iron, with a density between that of aluminum and iron.
    • Has excellent corrosion resistant characteristics
      • However it's sensitive to the effects of nitrogen and oxygen so it must be converted into titanium dioxide using chlorine gas and a reducing agent.
    • Classified as
      • Alpha Alloys - Have medium strength and good elevated-temperature strength.
        • Can be welded and used in forgings
        • is 8A1-1Mo-1V-Ti
      • Alpha-Beta - Most versatile, have medium strength in the annealed condition and much higher strength when heat treated.
        • Not weldable, it has good forming characteristics
      • Beta - Have medium strength, excellent forming characteristics
        • Large quantities of high-density alloying elements.
        • Can be heat treated to a very high strength.
    • The grain structure of Titanium is refined when aluminum is added.
    • Copper is added to produce a precipitation- hardening alloy.
Alloy Composition Tensile Strength Elongation
Alpha 5% AL - 2.5% SN 130 KSI 15%
Alpha-Beta 6% AL - 4% V 140 KSI 15%
Alpha-Beta Heat-Treated 6% AL - 4% V 180 KSI 7%
Beta 13% V - 11% CR - 3% AL 150 KSI 15%
Beta Heat-Treated 13% V - 11% CR - 3% AL 200 KSI 6%
  • Nickle and Its Alloys
    • Monel - Contains about 68% nickle and 29% copper along with small amounts of iron and manganese.
      • Can be welded and has very good machining characteristics.
    • Inconel - 80% nickle, 14% chromium, and small amounts of iron and other elements
      • Used in turbine engines because of their ability to maintain their strength and corrosion resistance under extremely high temperature conditions.
      • Is similar in appearance and are frequently used in the same areas so a test is needed to differentiate between unknown metal samples.
  • Copper and Its Alloys
    • Primary metal used for electrical wiring, due to its excellent electrical and thermal conductivity.
    • ** Alloys** :
      • Brass - contains zinc and small amounts of aluminum, iron, lead, manganese, magnesium, nickel, phosphorous, and tin.
        • Brass with zinc content of 30 to 35% is very ductile
        • Brass with zinc content of 45% has relatively high strength.
      • Bronze - is a copper alloy that contains tin
        • With 25% tin is used in bushings, bearings, fuel metering valves, and valve seats.
        • With 11% tin is used in tube fittings.
      • Beryllium - Most common. Consists of 97% copper, 2% beryllium and sufficient nickel to increase its strength.
        • Tensile strength of 200ksi and 70KSI in its annealed state
        • Used in diaphragms, precision bearings and bushings, ball cages and spring washers.
  • Heat Treatment of Aluminum Alloys - is a series of operations involving the heating and cooling of metals in their solid state.
    • Solution Heat Treating - Process of heating certain aluminum alloys to allow the alloying element to mix w/ the base metal.
      • In this process, metal is heated in either a molten sodium or potassium nitrate bath or in a hot air furnace.
      • Soaked - Metal is heated to just below its melting point and is held within +/- 10 degrees F until the alloy element is uniform throughout
      • Quenched - Once the metal is soaked, it is removed and cooled within 10s of leaving the furnace.
    • Precipitation Heat-Treatment - Reheating a metal once its been quenched and is allowed to soak for a specific period of time.
      • Artificial Age hardening * Precipitation hardening - Develops hardness, Strength, Corrosion resistance by locking a metals grain structure
      • Precipitation Heat Treatment /
    • Annealing - Is a process that softens a metal and decreases internal stress and is the opposite of hardening
    • Non-Heat treatable alloys - 1x commercially pure aluminum does not benefit from heat treatment since there are no alloying elements.
    • Heat-Treatment Identification
      • -T - Solution Heat Treated
      • -T2 - Annealed (Cast Products Only)
      • -T3 - Solution heat treated followed by natural aging at room temperature to a stable condition.
      • -T5 - Artificially aged after being rapidly cooled during fabrication process such as extrusion or casting.
      • -T6 - Solution heat treated, followed by artificial aging (precipitation heat-treating)
      • -T7 - Solution heat treated and then stabilized to control its growth and distortion
      • -T8 - Solution heat treated, strain hardened and artificially aged
      • -T9 - Solution heat treated, artificially aged then strain hardened
      • -T10 - Artificially aged and then cold worked
    • Reheat Treatment - Material which has been previously heat-treated can generally be reheat treated any number of times
      • The number of solution heat treatments allowed for clad materials is limited due to increased diffusion of the core material.
Non-Heat Treatable Alloys Copper Silicon Maganese Magnesium Zinc Chromium
1100
3003 1.2
5052 2.5 0.25
Heat Treatable Alloys
2017 4.0 0.5 0.5
2117 2.5 0.3
2024 4.5 0.6 1.5
6061 0.25 0.6 1.0 0.25
7075 1.6 2.5 5.6 0.3
  • Strain Hardening
    • Cold-working / Work hardening - process requiring mechanically working a metal at a temp below its critical range.
      • It alters the grain structure and hardens the metal.
    • Hardness Designators (Temper)
      • -F** - As Fabricated
      • -O - Annealed, Recrystalized (Wrought Materials Only)
      • -H - Strain Hardened
      • -H1 - Strain Hardened only
      • -H2 - Strain Hardened and Partially Annealed
      • -H3 - Strain Hardened and Stabilized
      • -Hx2 - Quarter Hard
      • -Hx4 - Half Hard
      • -Hx6 - Three Quarters Hard
      • -Hx8 - Full - Hard
      • -Hx9 - Extra - Hard
  • Ferrous Metals
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