6.1 ferrous materials Flashcards
what is a ferrous metal?
an alloy that has iron as its main ingredient
what are the properties of iron in the pure state?
It is ductile, soft and can be easily formed.
What is a disadvantage of iron?
It is heavy
When iron reacts with oxygen, what is it more commonly known as?
Iron oxide (rust)
How is pig/cast iron made?
the iron ingot is mixed with limewater and coke and passed through hot air to produce carbon monoxide which absorbs oxygen. The limestone forms a slag which floats and is removed.
What properties does pig/cast iron have?
It is brittle.
What is the weight to strength ratio of pig/cast iron?
It has a low strength to rate ratio.
How is steel created?
The pig/cast iron is reheated and pure oxygen is passed through it. Then a controlled amount of carbon is then forced through it.
What are the properties of steel?
High density and susceptible to corrosion.
What are the 7 types of strength?
Fatigue
Torsional
Tensional
Shear
Flexural
Compressive
Impact
What is Fatigue strength?
The ability of a material to withstand repeated loading
What is compressive strength?
A materials ability to withstand squeezing or pressing
What is Torsional strength?
A materials ability to withstand twisting
What is impact strength?
A materials ability to withstand sudden forces and shock.
What is flexural strength?
A materials ability to withstand bending
What is shear strength?
A materials ability to withstand coplanar stress over a cross section
What is tensile strength?
A materials ability to withstand tensional stress.
What is hardness?
To resist tearing, penetration or abrasion
What is malleability?
To be bent without damage (cracking)
What is ductility?
To be drawn into a thin wire
What is brittleness?
To crack when stress is applied
What is toughness?
To resist tearing
what is conductivity?
the property that enables a metal to carry heat or electricity
what is fusibility?
ability of metal to be joined by heating and melting
what is density?
mass per unit volume
What does carbon allow steel to be?
Heat treated
What is the benefit of heat treatment?
To increase hardness and strength
What are the disadvantages of adding carbon?
It makes steel more brittle and also decreases its weldability.
What percentage is low carbon?
0.1%-0.3%
What percentage is medium carbon?
0.3%-0.5%
What percentage is high percentage carbon?
0.5%-1.05%
What does Sulphur cause steel to be?
Brittle
What does silicon cause steel to be?
Hard and ductile
What does phosphorous cause steel to be?
increases yield strength and corrosion resistance in regards to the atmosphere.
What does nickel cause steel to be?
increases yield strength, hardness and overall strength
What does chromium cause steel to be?
Adds strength, hardness and corrosion resistance
What does molybdenum cause steel to be?
Reduces grain size and increases elastic and impact limits. Extremely wear resistant and has great impact strength
What does Vanadium cause steel to be when combined with Chromium?
Ductile, hard, strong, tough
What is another name of stainless steel?
CRES
What are the three groups Stainless steel are divided into?
Ferritic
Austenitic
Martensitic
What series are austenitic?
200 and 300 series
Austenitic stainless steel are non magnetic, but when are they magnetic?
When they are cold worked
What series are ferritic metals part of?
400 series
What properties do ferritic metals have?
Ductile, malleable and can be easily welded. Non magnetic
Are ferritic metals magnetic?
no
What are martensitic stainless steels relative to?
the 400 series
What are martensitic stainless steels properties?
magnetic, corrosion resistant
What is quenching?
Rapidly cool a material after heating it
What is annealing?
Softening the iron to relieve internal stresses
What is normalizing?
Heating a material above its critical limit and then heat soaking it at that temperatures. Then you allow it to cool naturally.
What does normalizing relieve?
Internal stresses. (As the carbon is allowed to precipitate out)
What is tempering used to do?
Soften the steel for use.
What does tempering relieve caused by quenching?
Internal stresses.
What can you use to accurately measure temperature when tempering?
Pyrometer or Thermocouple oven
What is a less accurate way of measuring the temperature when tempering?
Observing the colour
Observing the colour
Cooler
Does blue mean it is hotter or cooler?
hotter
What is case hardening?
When a material is hard on the outside but tough on the inside
What are the two types of direct hardening?
Flame and induction hardening.
In flame hardening, the steel is made of a uniform or different composition throughout?
Uniform
How do you carry out flame hardening?
You heat the steel with an oxy. torch and then quench it with a jet of water.
In induction hardening, the whole circumferance of the steel is heated simultaneously by what?
Induction coil.
As soon as the steel has reached necessary temperature in induction hardening, what happens?
The current is switched off and immedietaly quenched by jets of water.
Whats the last two digits represent?
The carbon content
What is iron alloyed with to create steel?
Carbon
Pure iron is known as what?
Ferrite
What carbon percentage does ferrite absorb?
0.2%
What cubic structure does ferrite have?
Body centred cubic lattice
What cubic structure does austenite have?
Face centred cubic lattice
What percentage does Austenite absorb?
2%
What are the properties of cementine?
Hard
What number is the carbon content of cementite lower than?
2%
What are the properties of pearlite?
Two phased lamella structure
What percentage does pearlite absorb?
0.8%
Steel is hardened by raising or lowering it below its critical temperature?
Raising
Is Austenite heated above or below its critical temperature?
Above
Is ferrite heated above or below its critical temperature?
Below
Is martensite heated above or below its critical temperature? And what action do you take when it’s accomplished
Above and is quenched quickly
What is quenching?
Rapidly cooling a material after heating
What does annealing do?
Relieve internal stresses and softens the steel
Does annealing need to be heated above or below its critical temperature?
Above and heat soaked
Is normalising heated above or below its critical temperature?
Above
