6.1 Ferrous Materials Flashcards by Reinhard Hein

Properties of pure iron

Ductile, soft and easily formed
Silvery white in colour

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How is iron produced?

Iron ore mixed with coke and limestone , and submitted to hot air

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how does the corrosion resistance of 2024 aluminium alloy rate

relatively low

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What is pig iron (cast iron)

Iron with high carbon content
Slag is removed

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Where is iron used in the engine

Valve guides
Piston rings

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What is the base of steel?

Iron

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How to make steel?

Pig iron is re-melted and pure oxygen is forced through the metal, combining with carbon

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What is hardness

Ability to resist cutting, penetration, or abrasion

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What is malleability

A material ability to be bent formed or shaped without cracking

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What is brittleness

Materials tendency to break or shatter when exposed to stress

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What is toughness

Materials ability to resist tearing or breaking when bent or stretched

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What is density

Mass per unit volume

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Does higher carbon content increase the malleability and weld ability of steel?

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What is high carbon steel used for?

Springs, files, cutting tools

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What is medium carbon steel used for

Machining processes or surface hardness required

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What is low carbon steel used for

Safety wire and secondary structure

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What is carbon content of low carbon steel?

0.1-0.3

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What is carbon content of medium carbon steel

0.3-0.5

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What is the carbon content of high carbon steel?

0.5-1.05

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What does sulphur cause in steel

Causes steel to be brittle when rolled and forged
Must be removed in refining process

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What does silicon cause in steel

Acts as a hardener
In low carbon steel it can be detrimental to surface finish
Also improved ductility

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What does phosphorus do in steel

Improves low carbon steel resistance to atmosphere corrosion
raises
Yield strength

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What does the first 2 digits identify in the classification of steels

Principal alloying element

What does the last two digits indicate in the classification of steels

Average carbon content

What is heat treatment of steel

Heating and cooling carbon steel to change its physical and mechanical properties without changing its original shape and size

what is ferrite

pure iron, body centred cubic lattice

what is austenite

face centred cubic form of iron, which can absorb a lot more carbon into a solid solution

what is cementite

chemical compound made up of iron and carbon, very hard, known as carbide

what is pearlite

2 phased, lamellar structure

how is steel hardened

by raising its temp to above the critical temp

what are the most important factors in the heat treatment of carbon steel (3)

carbon content, temp, time taken to cool

which has got a face centred cubic crystal

austenite

what has got a body centred cubic

ferrite

what has got a body centred tetragonal crystal

martensite

what is the critical temperature

temp at which a phase change occurs in a metal, during heating or cooling

what happens to the crystal structure above the critical temperature

the steel crystal structure changes from a body centred cubic to a face centred cubic

what is quenching

rapidly cool material

what is annealing

softens steel, relieves internal stresses.

what is the process behind annealing

heating a steel to 10c above its upper critical limit and heat soaking it at this temperature

can annealed parts be used on aircraft

what is normalising

heating steel to 38c above the upper critical limit and soaking for a prescribed amount of time

at what temp is metal cooled after normalising

room temp

what is tempering

a method to decrease the hardness, increasing the ductility and toughness of the metal

what is the most common way to measure the temperature of the tempering process

pyrometers or thermocouple controlled ovens, YOU CAN OBSERVE THE COLOUR OF THE METAL(LESS ACCURATE)

which components use case hardened steel

engines and landing gear

what steels are best suited for case hardening

low carbon and low alloy steels

what are the 2 methods to case harden steel

carburising and nitriding

what is direct hardening

flame or induction hardening process surface is heated rapidly

what is flame hardening

surface layers recieve extra heat treatment and immediately queniching with jet of water

what is induction hardening

steel heated with induction coil (whole circumference)

what is polyaddition

a reaction of 2 different types of molecules when reactive groups are brought together

what are the 2 main epoxy resin systems used in composite structures

epoxy is used for external and structural phenolic is used for internal and fittings

what is polymerisation

a chemical reaction generally carried out in the presence of a catalyst which combines small molecules (monomers) containing a double bond, into long chain molecules

what is the most practical way of controlling corroding steel

complete removal of corrosion by mechanical means and maintaining a protective coating