Intro Flashcards
Define Toughness
Measure of the amount of energy a material can absorb before fracturing
Toughness Equation
Energy Stored / Unit Volume
Units: Jm^-3
3 Main Types of welding
Arc Welding, Torch Welding, Resistance Welding
Arc Welding
Uses electricity to melt base metal (3000-20000 degress C)
Torch Welding
Uses welding rod and open flame to melt metal
Resistance Welding
Uses heat generated by resistance to an electrical current
What is Poisson’s ratio?
The ratio of the lateral strain to the tensile strain:
v= -(lateral strain)/(tensile strain)
Define Concrete
Ceramic composite material, composed of a a coarse granular material embedded on a hard matrix of a cement paste.
Uses for Concrete
Structural Building such as bridges, buildings, dams and road pavement
What are Corrosion and Heat Resistant steels?
Otherwise known as stainless steels, they are Iron alloys with at least 11.5wt%Cr
Why are corrosion resistant steels corrosion resistant?
Because the Chromium in it oxidises more preferentially to Iron oxides (rust)
What is Hardness?
Hardness is a measure of the resistance of a material to permanent deformation
Give the Vickers hardness equation
HV= 1.854P/d^2
Where P is the applied force and d is the mean of the diagonals of the indentation
Info on Concrete reinforcement
Concrete’s tensile strength is 10 to 15 times lower than its compressive strength.
Meaning it’s usually cast containing steel bars if the application means it will be subject to tensile forces
How is Cement made?
The raw materials are ground, blended and fed into rotary kilns fired by gas, oil or usually coal.
Formula to remember
C3S2.3H20
Define Glass
Inorganic product of fusion which has been cooled to a rigid condition without crystallisation.
What is the lever rule?
Weight fraction of solid and liquid in equilibrium at a set temperature equal one.
Weight fraction of solid equation
Fs=(Co-Cl)/(Cs-Cl)
Weight fraction of Liquid equation
Fl=(Cs-Co)/(Cs-Cl)
What are Steels?
Iron-Carbon alloys containing less than 2wt%C but usually containing around 0.8%
What phase transformations are associated with Steel?
austenite, cementite, ferrite
Associated with the iron rich corner of the Fe-Fe3C phase diagram
Low carbon Steel
up to 0.25wt%C, used for cans, pressings, wires, nails
Medium Carbon Steel
between 0.25 and 0.6wt%C, used for Wire rope, Gears, axles, forging, castings, springs
High Carbon Steel
Up to 0.6wt%C, Used for tools, ball bearings, dies and piano wire
Hume Rothery Rules
Conditions required for complete solid solubility:
Same crystal structure,
Atomic dimensions differ by no more than 15%
Same valency
What does the second hume rothery rule mean?
Only substitutional solutes can be found in complete solid solubility
Youngs Modulus
Stress/Strain,
Gradient of stress strain curve in the elastic reigon
Stress
Force/Area
Strain
Extension/Original length
Polycrystalline
More than one crystal, meaning grain boundaries are present
Single Crystal
No grain boundaries, one crystal
Raw materials in cement
Lime, Silica, Alumina, Iron Oxide
