Crystal Structure and Plain Carbon Steel Flashcards
Equiaxed grains metal properties
Ductile, Softer
After cold working, describe what are the grains like and list properties of the metals.
Distorted Grains,
Properties: Stronger, Harder,
more brittle and less ductile,
higher internal stress
BCC metals
alpha-iron, tungsten
FCC metals
Aluiminium, copper, gamma-iron
HCP/CPH metals
Magnesium, Zinc, Titanium at low temp.
What are the 2 elements harmful to plain carbon steels?
Sulphur and phosphorus
Allotropic element
Iron, can exist in more than one physical form (BCC, FCC)
2 structure name when carbon dissolves in FCC and BCC iron
FCC iron: Austenite
BCC iron: Ferrite
What are the properties of austenite and its crystal structure?
Properties: soft, non-magnetic and very ductile
Crystal structure: FCC
What are the properties of ferrite and its crystal structure?
properties: soft, ductile and magnetic
BCC structure
Properties of cementite
very hard and brittle
properties of pearlite
stronger and harder than ferrite but tougher than cementite
Maximum carbon austenite can dissolve is
0.8%
An increase in carbon content in plain carbon steel will result in an increase in
tensile strength (up to 0.8%C)
hardness
wear resistance
An increase in carbon content in plain carbon steel will have a decrease in
ductility (evidence from % elongation) toughness machinability weldability corrosion resistance
% carbon of dead mild steel, mild steel, medium carbon steel, high carbon steel, carbon tool steel
Dead mild: 0.05 - 0.15% Mild steel: 0.15 - 0.3% Medium carbon: 0.3 - 0.6% High carbon: 0.6 - 0.8% Carbon tool: 0.8 - 1.4%
Application of dead mild steel and mild steel
dead mild: car body, tubes, chains
mild steel: ship plate, steel sections for constructions
application of medium carbon steel, high carbon steel and carbon tool steel
medium carbon: gears, crankshafts, axle
high carbon: screw drivers, hammers, wrenches
carbon tool steel: chisels, files, axes, drills
