What are the types of cast iron?
- Gray
- Ductile
- White
- Malleable
- Compacted graphite
What are the characteristics of gray iron?
- Graphite flakes
- Weak & brittle in tension
- Stronger in compression
- Excellent vibrational dampening
- Wear resistant
What are the characteristics of ductile iron?
- Mg and/or Ce is added
- Graphite nodules
- Matrix is often pearlite which is stronger but less ductile
What are the characteristics of white iron?
- Less than 1 weight % Si
- Pearlite + cementite
- Very hard
- Very brittle
What are the characteristics of malleable iron?
- Heat-treated white iron at 800 - 900 deg C
- Graphite in rosettes
- Reasonably strong and ductile
What are the limitations of ferrous alloys?
- Relatively high densities
- Relatively low electrical conductivity
- Generally poor corrosion resistance
What are the characteristics of compacted graphite iron?
- Relatively high thermal conductivity
- Good resistance to thermal shock
- Lower oxidation at elevated temperatures
What is a ferrous alloy?
A metal alloy where iron is the primary component (steels 0 - 1.4 wt% C and cast irons 3 - 4.5 wt% C)
What is a nonferrous alloy?
A metal alloy where iron is not the primary component
What are the types of nonferrous alloys?
- Cu
- Al
- Ti
- Mg
- Noble
- Refractory
Copper alloys
- Brass (corrosion resistant)
- Bronze
- Cu-Be (hardened)
Aluminum alloys
- Low density
- Solid solution or precipitant
- Strengthened
Magnesium alloys
- Very low densities
- Ignites easily/highly flammable
Titanium alloys
- Relatively low densities
- Reactive at high temperatures
Noble metals
- Ag, Au, Pt
- Oxidization/corrosion resistant
Refractory metals
- Nb, Mo, W, Ta
- High melting temperatures
What are the types of metal fabrication methods?
- Forming (rough stock shaped)
- Casting (molten metal molded)
- Miscellaneous (powder metallurgy and welding)
What are the types of metal forming?
- Forging (hammering or stamping)
- Rolling (hot or cold)
- Drawing (pulling)
- Extrusion (pushing)
What is the difference between hot and cold working?
Hot working
- Deformation temperature high enough for recrystallization
- Large deformations
Cold working
- Deformation below recrystallization temperature
- Strain hardening occurs
- Small deformations
What are the characteristics of metal casting?
- Metal is melted in a furnace where alloying elements may be added, then cast in a mold
- Common and inexpensive
- Good production of shapes
- Weaker products, often have internal defects
- Good option for brittle materials
What are the types of metal casting?
- Sand casting (large parts)
- Investment casting (low-volume, complex shapes)
- Die casting (high volume, low melting temps)
- Continuous casting (simple shapes)
What is investment casting?
1) Plaster of paris poured and hardened around wax pattern
2) Wax melts, leaving hollow plaster mold
3) Molten metal poured in and solidified
What is powder metallurgy?
- Good for intricate/precise shapes
1) Compaction of metal powders
2) Densification heat treatment
What is welding?
A technique for joining metals in which the actual melting of the pieces to be joined occurs in the vicinity of the bond. A filler metal may be used to facilitate the process.
