Unit 2 : Metals Flashcards
very low content of alloying elements and small amounts of manganese.
Plain carbon steel
alloys of iron and carbon (may contain other alloying elements)
Steel
Carbon content in the range of 0.3% to 0.6%
Medium Carbon Steel
carbon content of 0.6% - 1.4%
High Carbon Steel
a group of steels that contain at least 11% Cr, exhibits extraordinary corrosion resistance due to formation of a very thin layer of Cr2O3
on the surface.
Stainless steel
composed of alpha ferrite (BCC)
Ferritic Stainless Steels
can be heat treated
Martensitic Stainless Steels
austenite (gamma) phase field is extended to
room temperature; most corrosion resistant
Austenitic Stainless Steels
ultra high-strength due to precipitation hardening
Precipitation-Hardening (PH) Stainless Steels
ferrite + austenite
Duplex Stainless Steels
increases strength and hardness and decreases ductility and notch
impact toughness of steel
Phosphorous
strength and hardness; decrease ductility and weldability; affects
hardenability of steel
Manganese
decreases ductility and notch impact toughness, weldability decreases; found in the form of sulfide inclusions
Sulfur
one of the principal deoxidizers used in steel making; in low-carbon steels, is generally detrimental to surface quality
Silicon
detrimental to hot-working steels; beneficial to corrosion resistance (Cu >0.20%)
Copper
ferrite strengthener; increases the hardenability and impact strength of steels
Nickel
increases the hardenability; enhances the creep resistance of low-alloy
steels
Molybdenum
contains graphite in the form of flakes; named after its grey
fractured surface; C: 3.0 - 4.0 wt%, Si: 1.0 - 3.0 wt%
Weak and brittle in tension (the graphite
flake tips act as stress concentration
sites); stronger in compression
Excellent damping capacity, wear
resistance
Grey cast iron
Castings are stronger and much more ductile than grey iron as the stress concentration points existing at the flake tips are eliminated
Castings are stronger and much more ductile than grey iron as the stress concentration points existing at the flake tips are eliminated
Nodular or ductile iron
C: 2.5 - 3 wt%, Si: 0.5 - 1.5 wt%; most of the carbon is in the form of cementite; names after its white fracture surface
Results from faster cooling; contains pearlite + cementite, not graphite; thickness variation may result in nonuniform microstructure from variable cooling
Very hard and brittle
Used as intermediate to produce
malleable cast iron
White Cast Iron
C: 2.3 - 2.7 wt%, Si: 1.0 - 1.75 wt%
Obtained by heat treating white iron fora prolonged period that causes
decomposition of cementite into graphite
Malleable Cast Iron
occurs as blunt flakes or with a worm-like shape (vermicular); C: 3.1 - 4.1 wt%, Si: 1.7 - 3.0 wt%
As castable as grey iron, has a higher
tensile strength and some ductility
Relatively high thermal conductivity,
good resistance to thermal shock, lower
oxidation at elevated temperatures
Compact Graphite Iron
the most common alloy of Cu - it’s an alloy with Zn
Brass
Copper alloys containing tin, lead, aluminum, silicon and nickel
Bronze
a light metal (ρ = 2.7 g/cc); is easily machinable; has wide variety of
surface finishes; good electrical and thermal conductivities; highly reflective to heat and light
Aluminum
melts at 1670 oC and has low density of 4.51 g/cc (40% lighter
than steel and 60% heavier than aluminum)
Titanium
a high-density, high-strength metal with goof ductility and excellent
corrosion resistance and high temperature properties
Nickel
lightest among commonly used metals (1.7 g/cc); melting point is 650 oC and it has HCP structure. it is very reactive and readily combustible in air; can be used as igniter or firestarter
Magnesium
shiny, soft, heavy, rare, resistant to corrosion, very valuable metal
Gold
A soft, white, lustrous metal; it exhibits the highest electrical conductivity, thermal conductivity, and reflectivity of any metal
Silver
