6.2 non ferrous metals Flashcards
What does non ferrous mean?
A metal that does not have iron as it main base material
Are non ferrous metals magnetic or non magnetic?
Non magnetic
What are 4 examples of non ferrous materials?
Aluminium, copper, titanium, manganese
What ore is aluminium extracted from?
Bauxite
What are the properties of pure aluminium?
Lightweight, lustrous, white,
What properties does aluminium obtain when combined with zinc and copper? (Fractions)
Strong with only 1/3 of the weight of steel.
What is the corrosion resistance like in this alloy?
Good
In Wrought Aluminium, what are the different series?
1-Pure aluminium
2-Copper
3-Manganese
4-Silicon
5-Magnesium
6-Magnesium and Silicon
7-Zinc
8-Other elements
9-Unused elements
What are the properties of Series 1? (When are they used? What can they be? Corrosion resistance and Conductivity?)
They are used when strength is needed. Can be strain hardened, they have good corrosion resistance and good electric conductivity.
What are Series 2 susceptible to?
Corrosion
What can Series 3 not be?
Heat Treated
Why does Series 4 have good weldability and brazing?
It has a lower melting temperature
What are the properties of Series 5? (C,W)
Good weldability and corrosion resistance.
What can Series 6 be that 3 cannot be?
Heat treated
Because Series 7 has high tensile strength, What does that mean in terms of its properties?
It is harder and stronger.
How can you increase an aluminium alloys materials corrosion resistance?
A thin layer of pure aluminium is cladded on it
What percentage does the Al-clad have to be of the material?
3%-5%
What can abrasions to the Al-clad cause?
Corrosion or stress points.
How do you recognize Aluminium cladded material?
It says Al-Clad, ALC, ClaD, A
What is the most popular magnesium alloy?
AZ31
What is Magnesium density compared to Aluminium?
Lower and 2/3 of the weight
Magnesium is highly susceptible to what?
Corrosion
How can this be overcome?
By treating the surface with chemicals that form an oxide film and exclude oxygen.
How do you stop Magnesium cracking when formed?
By heating the parts before forming (hot dimpling)
What is dangerous about magnesium?
It burns rapidly in any form.
What does solution heat treatment of Magnesium increase?
Tensile strength, resistance to shock and ductility.
What does precipitation heat treatment do increase?
It increases the yield strength and hardness
What is precipitation heat treatment?
Heating it below its temperature for solution heat treatment and holding it there.
How can the ageing process be slowed down?
By storing the material at a sub-zero temperature (-20 degrees) straight after being quenched.
How can the ageing process be increased?
By heating the material 160-260 degrees and allowing it to soak.
What are the properties of Aluminium in terms of weight and strength
Lightweight and very high strength
Alloy with high zinc content require what in order to achieve full strength?
Thermal treatment
What does temper designation T stand for?
Solution heat treatment
What is the name for this?
Artificial age hardening.
What does T3 stand for?
Solution heat treated followed by strain hardening
What does T4 stand for?
Solution heat treatment followed by natural age hardening
What T6 stand for?
Solution heat treatment followed by artificial age hardening
What does T36 mean?
Solution heat treated but thickness reduced by 5% (by cold rolling)
Rivets made of alloys 2017 and 2024 are hard so have to receive what?
Several heat treatment so it’s suitable to be used as rivets.
Why are the number of solution heat treatments allowed for clad materials limited?
Because of the diffusion of core material into the cladding
What does the diffusion decrease?
Corrosion resistance
How many heat treatments is Al clad limited to?
3
Non heat treatable aluminium are designated in what?
1xxx 3xxx 5xxx
Non heat treatable alloys can be adjusted by cold what?
Rolling and working
Alloy 5052 contains 2.5% of what? (5xxx)
magnesium
It also contains a small amount of what?
Chromium
What is it called when strength is increased by cold working?
Mechanical hardness
Strain hardening is also known as what?
Cold working or work hardening
Strain hardening works a material above or below it’s critical range?
Below
Strain hardening alters the grain structure and makes the alloy what?
Harder
What does strain hardening consist of?
Pressing, rolling and drawing
Hardened designation F means?
Fabricated
Hardened designation O means?
Annealed
Hardened designation H means?
Strain hardened
H1?
Strain hardened only
H2?
Strain hardened and partially annealed
H3?
Strain hardened and stabilised
Hx2?
Quarter hard
Hx4?
Half hard
Hx6?
Three quarter hard
Hx8?
Fully hard
Fully hard
Fully hard
What must you ensure when annealing clad aluminium alloys?
They must be heated as quickly and as carefully as possible
Why must you ensure quickness when annealing clad aluminium alloys?
Because the core material can diffuse and mix into the cladding increasing corrosion
How is mechanical hardness started?
By prolonged operations. It restricts further work
A material that has been previously heat treated can be reheated several times for what reason?
To relieve interns, stresses
What does strain hardening do to the grain structure?
It alters it to make the material harder
What is solution heat treatment?
When an alumiunium alloy is heated so the base material mixes with the alloying element
How is solution heat treatment carried out?
The material is heated in a salt bath or hot furnace just below its melting point. The temperature is maintained +-5. It is then quenched
For large forging, what is essential?
Hot water
What is the amount of time an alloy can take inbetween
removing the alloy from the furnace and quenching?
10 seconds
What is spray quenching?
Using high velocity water sprays
What are the benefits of spray quenching?
Alleviates cracking and minimizes distortion
Thin metal warps and distorts when quenched so what must you do?
Straighten it immediately
If a salt bath was used, what must you ensure and why?
The salt is washed off because it can corrode
