Materials - Metals 1

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What are the top steel producing countries?
Steels - 1630 mil metric tonnes produced p a. Top 10 steel countries: China, Japan, India, USA, Russia, South Korea, Germany, Turkey, Brazil, Ukraine
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What are steels that have been used in Civ Eng from history to now?
Coal Brookdale, 1779, cast iron bridge, Eiffel tower - wrought iron, 1st wrought iron bridge: Firth of Forth rail, galvanised steel used in modern bridges like Millau Viaduct
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What are non ferrous materials used in Civil Engineering?
Aluminium cladding, copper radwaste container, lead roof
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What is bronze made from?
Bronze in an alloy of copper from malachite (copper carbonate hydroxide) and tin, used in history. Pure metals aren't commercially used
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What is bonding in metals?
Electrons from outer shells escape. Metallic bonds exist between electrons and metal ions, which are very strong. Regular structure means high mp and bp. Alloys are added to metal
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What are FCC, HCP and BCC structures? (Iron BCC, Al FCC)
FCC - Face centred cubic with points on lattice ends, HCP - hexagonal close packed with hexagonal shaped atom layers, body centred cubic, BCC, atoms at eight corners of cubes and centre (Cr, alpha Fe etc_P
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What are some crystal imperfections?
Vacancy solutes are lack of atoms, grain boundaries, substitutional solutes (different element replaces one in lattice), interstitial solutes (small element added to full structure),dislocations
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What are grain boundaries?
Grain boundaries are interface between adjacent crystalline regions with different orientations. Fracture can occur between boundaries
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How do dislocations affect strength of metals?
Dislocations are extra plane of atoms in crystal structure, stress required to plastically deform crystal less if they can move. Edge dislocations movement reduces yield stress as it's easier to move one row of bonds than entire plane
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What are alloys? How do they affect metals?
Alloys are pure metals with other elements, alloy properties affected by composition and microstructure. Different grain size and orientation affect microstructure
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What is bronze?
Bronze consists of copper and 15% tin. Can be cast or cast and annealed, same composition but completely different properties
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What are steel alloys?
Steel alloys are alloy of iron and steel, <2% carbon, 1% manganese, small amounts silicon, phosphorus, sulfur, and oxygen. More than 3500 grades of steel alloy with most modern steels made in last 20 years and better properties by microstructure cont
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How does reducing grain size affect strength?
Reducing grain size increases number of grain boundaries, prevents dislocations slipping and increases yield stress
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What is the Hall-Petch equation?
Yield stress = stress0 (constant) + k (constant)*d^-1/2 (d=diameter of grain)
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What does work hardening achieve?
Dislocations have strain field with compressive above line and tensile below. Barrier to dislocation motion. More stress increases dislocation density leading to dislocations moving on intersecting slip planes piling up, increasing yield stress
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What are solid hardening and precipitation strengthening/hardening?
Solid hardening: solute atoms have strain field which interacts with dislocation strain field reducing motion. Precipitation hardening/strengthening: fine distribution of second phase particles with field which locks dislocations increasing yield str
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Where does yield stress act?
Lower yield point is the yield stress.
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What do phase diagrams show?
Phase diagrams show the different phases which exist for Fe-C at different temperatures and compositions
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What's the formula for liquid fraction in phase diagrams?
Liquid fraction= difference between middle of tie point and solid boundary/difference between solid and liquid boundary
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What is the formula for solid fraction?
Solid fraction = difference between middle of tie point and liquid/solid and liquid distance
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What do phase diagrams assume?
Phase diagrams assume slow cooling rate and equilibrium conditions as solid forms
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What are tie lines?
Tie lines act along boundaries (ie - C5 at alpha-solid line, C in middle, C6 at solid-beta line for solid tie line)
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How do eutectic alloys solidify in phase diagrams?
At eutectic alloy, solidification acts at centre where Alpha liquid, beta liquid, and alpha and beta boundary are and nucleation sites grow as temperature falls down middle, leading to solid
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How do hypoeutectic alloys form?
For hypoeutectic alloys, solidification begins at alpha liquid, a+B boundary leading to formation of solid alpha and eutectic
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Other cards in this set

Card 2

Front

What are steels that have been used in Civ Eng from history to now?

Back

Coal Brookdale, 1779, cast iron bridge, Eiffel tower - wrought iron, 1st wrought iron bridge: Firth of Forth rail, galvanised steel used in modern bridges like Millau Viaduct

Card 3

Front

What are non ferrous materials used in Civil Engineering?

Back

Preview of the front of card 3

Card 4

Front

What is bronze made from?

Back

Preview of the front of card 4

Card 5

Front

What is bonding in metals?

Back

Preview of the front of card 5
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