Material science 2nd exam

• Carbon is the chemical element with the symbol C and atomic number 6
• Carbon is a member of group 14 on the periodic table, it is non-metallic and tetravalent, making four electrons available to form covalent chemical bonds
• Carbon has several allotropes, including diamond (hardest naturally occurring substance) and graphite (one of the softest known substances)
• Alloy Steel is a type of steel alloyed with elements like molybdenum, manganese, nickel, chromium, vanadium, silicon, and boron to increase strength, hardness, wear resistance, and toughness
• Alloy steels can be classified into low alloy steel and high alloy steel, with the boundary commonly accepted as 5% alloying element
• Charpy V-notch energy absorption test shows the relationship of ductile to brittle transition in absorbed energy at different temperatures
• Cryogenics refers to volatile compounds being retained in the liquid phase at low temperatures above the glass transition temperature
• Notch Ductility is the ability of steel to resist failure, dependent on composition, temperature, and grain structures within the steel
• Rockwell Hardness measures the permanent depth of indentation produced by a force/load on an indenter
• Tool Steels are carbon and alloy steels with characteristics like hardness, wear resistance, toughness, and resistance to softening at elevated temperatures
• Stainless Steels are iron alloys with a minimum of 10.5% Chromium, forming a passive layer on the surface to prevent corrosion
• Wrought Aluminum Alloy Designation System categorizes aluminum alloys based on characteristics and principal alloying elements
• Cast Aluminum Alloy Designation System is based on a 3-digit-plus-decimal designation indicating the principal alloying element added to the aluminum alloy
• 1xxx Series Alloys are non-heat treatable with ultimate tensile strength of 10 to 27 ksi, primarily selected for corrosion resistance and electrical conductivity
• 2xxx Series Alloys are heat treatable with ultimate tensile strength of 27 to 62 ksi, often used in aerospace and aircraft applications
• 3xxx Series Alloys are non-heat treatable with ultimate tensile strength of 16 to 41 ksi, used for heat exchangers and have good corrosion resistance
• 4xxx Series Alloys are heat treatable and non-heat treatable with ultimate tensile strength of 25 to 55 ksi, predominantly found as filler material for welding and brazing
• 5xxx Series Alloys are non-heat treatable with ultimate tensile strength of 18 to 51 ksi, readily weldable and used in shipbuilding, transportation, and pressure vessels
• 6xxx Series Alloys are heat treatable with ultimate tensile strength of 18 to 58 ksi, used in extrusions and structural components, solidification crack sensitive
• Aluminum Alloys
• Aluminum alloys are classified into different series based on their properties and applications
• 2XXX Series Alloys:

  • Unsuitable for arc welding
  • Some alloys in this series can be arc welded successfully
• 4XXX and 5XXX Series Alloys:

  • Used for welding 2XXX series alloys
  • Dependent on the application and service requirements
• 7XXX Series Alloys:

  • Heat treatable with ultimate tensile strength of 32 to 88 ksi
  • Used in high-performance applications like aircraft and aerospace
• Temper Designation (aluminum)
• An extension of the alloy numbering system consisting of letters and numbers connected by a hyphen
• Examples:

  • 6061 - T6
  • 6063 - T4
  • 5052 - H32
  • 5083 - H112
• Carbon Steels
• Classified based on carbon content: mild and low, medium, high, and ultra-high carbon steel
• Mild and Low Carbon Steel (0.16 - 0.29% carbon):

  • Common and cost-effective
  • Not brittle or ductile, malleable
  • Surface hardness can be increased through carburizing
• Medium Carbon Steel (approximately 0.30 - 0.59% carbon):

  • Balance ductility and strength
  • Good wear resistance, used in forging and industrial components
• High Carbon Steel (approximately 0.6 - 0.99% carbon):

  • Very strong, used for springs and high-strength wires
• Alloy Steels
• Ultra-High Carbon Steel (approximately 1 - 2% carbon):

  • Tempered to great hardness, used for specialized products like knives and axles
• Contain varying amounts of different metals and materials to specialize their properties
• Common materials added:

  • Chromium
  • Molybdenum
  • Nickel
  • Silicon
• Selection of Alloy Steels:

  • Analysis of desired dimensions and specifications
  • Properties differ based on forming method and alloy composition
• Grade P20 is a hardened, general purpose mould steel suitable for production of machined or EDM plastic mould and zinc die casting components
• Grade P20 is supplied prehardened to a Rockwell hardness of C32, with a melting point of 2790 OF and a yield strength of 130,000 psi
• Tool Steel Metallurgy / Chemical Composition includes seven main types of tool steels: Water-Hardening Tool Steels (W), Shock-Resisting Tool Steels (S), Mould Steels (P), Cold-Work Tool Steels, Hot Work Tool Steels (H), High-Speed Steels, and Special Purpose Tools Steels