IT 111 MANUFACTURING MATERIALS

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IT 111 MANUFACTURING MATERIALS

• Lecture 3
• Thomas E. Scott

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Standards Organizations

• American Society for Testing and Materials (ASTM)
• American Iron and Steel Institute (AISI)
• Society of Automotive Engineers (SAE)
• American Institute of Astronautics and
  Aeronautics (AIAA)
• NASA
• Department of Defense (DOD)

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ASTM Standards provide Letter designation for
standards that include specifications, test
methods, definitions, classification, suggested
practices

• F. Specific applications of materials
• G. Corrosion, deterioration
• H. Emergency Standards

• A. Ferrous Metals
• B. Nonferrous Metals
• C. Cement, ceramics
• D. Miscellaneous materials
• E. Miscellaneous Subjects

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Ferrous Metals (Iron)

• In industry, iron is mainly used in the form of
  steel
• Steel an iron carbon alloy with less than 2
  carbon
• Cast Iron more that 2 but less than 4 carbon

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Production of Iron

• Very little pure iron produced
• Usually ingot or iron powders
• Mostly steels with alloys carbon, silicon,
  nickel, chromium, manganese
• Plain carbon steel less that 1 alloying
  element of carbon, silicon, and/or manganese
• Low-alloy steel have small quantities of the
  above plus nickel, chromium, molydenum or others
  that alter the properties of steel
• High-alloy steel have more than 5 of alloying
  elements

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Source of Iron (Fe)

• Ores of iron
• Magnetite contains 65 iron
• Ferric oxide (Fe2O3) and Ferrous oxide (FeO)
• Highly magnetic (Lodestone)
• Hermatite contains 50 iron
• Ferric oxide (Fe2O3)
• Commonly know as rust
• Blood red
• Taconite contains 30 iron
• Green colored
• Contains a lot of silica

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Refining Iron Ore

• Heat ore in a furnace where air (oxygen) has been
  removed
• Produces coke
• Blast furnace force air at 1100 F to permit
  carbon oxygen combustion
• Iron melts
• Slag provides a protective barrier for purified
  iron
• Pure iron captured as ingots (Pigs)
• Contains roughly 4 carbon (cast iron)
• Yield is about 50 - 6000 tons of ore to produce
  3000 tons of pig iron

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Production of Steel (Conversion)

• Burn off carbon
• Blow hot air across the pigs and scrap iron
• Let the carbon burn
• Add exact amounts of carbon and alloys
• Draw off liquid into ingots
• Open Hearth 200 tons in 12 hours
• Bessemer 25 tons in 15 minutes
• Electric arc Expensive because of energy used
  (for finishing)

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Commercial Shapes of Steel Ingots

• Blooms
• Beams
• Channels
• Tubes

• Billets
• Bars
• Rods
• Wire

• Slabs
• Plates
• Pipe
• Sheets
• Coils

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Commercial Shapes of Steel
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Carbon in Steel
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Effect of carbon addition(Small increase
approx 0.1)

• More expensive
• Less ductile more brittle
• Harder
• Loses machinability
• Higher tensile strength
• Lower melting point
• Easier to harden
• Harder to weld

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Characteristics of Carbon Steels

• Cold working
• Plastic deformation at room temp
• Decrease thickness 4
• Increase tensile strength 50
• Work hardening results
• May require heat treating
• Examples
• Cold rolled steel
• Cold drawn tubing

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Other elements in steel

• Aluminum
• Oxygen remains in steel undesirable
• Adding aluminum (killed steel) causes oxygen to
  react with aluminum and negates rust formation
  (good for forging and piercing)
• Aluminum also promotes small grain size and
  therefore, toughness

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Other elements in steel

• Manganese
• Sulfur accumulates at grain boundaries
  undesirable
• Causes the steel to lose strength at high temp
• Manganese ties up the sulfur
• Increases strength, hardenability, and hardness

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Other elements in steel

• Boron increases hardenability
• Copper increases corrosion resistance
• Chromium corrosion resistance and hardenability
• Niobium increases strength
• Titanium high strength at high temp
• Tungsten carbide high hardness
• Vanadium toughness and impact resistance

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Steel

• Free Cutting (High sulfur)
• e.g., AISI 1111 up to 1151
• Easy machining
• Higher carbon XX44 for example, greater hardness
  and flame case hardening

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Nomenclature for steels Steel AISI and
SAEFour digit designator describes alloy content
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Nomenclature for steels

• Examples
• 1010 Plain carbon (C 0.1)
• 4030 Steel with 0.30 Molybdenum
• Standards table required to determine actual
  content, suggested use and properties
• Web access to clarify material properties
• - Often have to pay for it

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Nomenclature for steels

• Table 3-B of Kazanas
• Table 3-C of Kazanas
• Table 3-D of Kazanas
• Table 3-E of Kazanas
• Table 3-F of Kazanas
• Table 3-G of Kazanas
• Table 3-H of Kazanas

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Tool Steels

• High carbon high alloy
• High wear and heat resistance

• High strength hard
• Letter classification

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Tool Steels

• Examples
• W-1 Water hardening 1 carbon used for cold
  working of metals
• D3 High chromium with 2.25 carbon for cold
  working applications
• S2 Shock resistant hammer or chisel steel

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Tool Steels

• Table 3-I of Kazanas
• Table 3-J of Kazanas
• Table 3-K of Kazanas

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Tool Steels

• Must sustain high loads
• Often loads concentrated on surface
• May have elevated temperatures
• Often substantial shock loading
• Must be immune to cracking
• Often particular steel alloy types
• Seven basic types of tool steel

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Tool Steels

• Properties for tool steels
• Wear resistance
• Impact resistance
• High temperature capability
• Toughness

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Alloys in tool steels

• Carbon hardenability (gt0.6)
• Manganese reduce brittleness (lt0.6)
• Silicon for hot forming, strength and toughness
  (lt2)
• Tungsten hot hardness
• Vanadium hardness and wear resistance
• Molybdenum deep hardening, toughness
• Cobalt hot hardness
• Chromium hardenability (up to 12)
• Nickel toughness and wear resistance

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Cast Iron

• More than 2 carbon
• Lower strength since carbon flakes produce minute
  cracks
• Very susceptible to breaking (brittle)
• Grey cast iron almost no ductility
• White cast iron 1 silicon making it hard

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Nodular Cast Iron

• Nodular cast iron small amounts of calcium,
  cerium, lithium, magnesium, sodium
• Slow cooling produces spheres instead of plates
• Improves ductility 604020
• Tensile 60K, Yield 40K, 20 elongation
• Engine blocks, pistons, crankshafts

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Stainless Steel

• Normal Steels corrode rapidly if left uncoated
• Higher temperature, more rapid corrosion
• Chromium and nickel slow corrosion
• Stainless steels have Cr gt 12

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Stainless Steel

• Ferritic can be strengthened by work hardening
• Jewelry, utensils, automotive trim
• Austenitic non-magnetic
• 18/8 18 Cr, 8 Ni
• Low carbon low strength
• Food utensils
• Martensitic High strength
• Knives,
• Maraging superalloys, contain Moly and Titan

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Stainless Steel

• Numbering system
• 200s and 300s Austenitic
• 400s Ferritic and Martensitic

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Corrosion (Rust)

• Galvanic corrosion (electrolytic process)
• Corrosion sped up by
• Temperature
• Metal fatigue
• Cold working
• Retarded by
• Alloys
• Coatings