Materials Grain structure

Question 1

What is grain structure?

Answer 1

Grain structure is the arrangement of differently orientated grains that builds up metals.

Question 2

What does cold rolling do to the grain structure and how does this effect the properties of the material?

Answer 2

Once the material is cold rolled, the grain structure is elongated and distorted. As the grain structure stretches the material’s hardness and tensile strength increases, whilst the ductility decreases.

This diagram explains how the grain structure is stretched during cold rolling.

Question 3

What are the two main grains that build up the grain structure?

Answer 3

pearlite & ferrite

Question 4

What’s the difference between ferrite and pearlite?

Answer 4

ferrite is made entirely from iron and is give properties of ductility, where pearlite is made up from iron and iron carbide and gives the properties made for strength.

Question 5

When the percentage of carbon is steel increases, does the number of ferrite or pearlite increase?

Answer 5

pearlite

Question 6

what happen to the grain structure when you heat a high pearlite (high carbon) content piece of steel to 720 degrees?

Answer 6

a new grain structure appears, growing out of the grain boundaries.

Question 7

if there is not enough carbon in the steel, what happens if you try to quench steel heated to 720?

Answer 7

the needle-like structure does not receive enough carbon, and when cooled the steel reverts back to its original form.

Question 8

What are the two types of cast iron and what is the difference?

Answer 8

White and Grey cast iron

White cast iron has a carbon percentage of at least 2% and comes in the form of cement. White cast iron has improved strength, retains good hardness and higher temps. White cast iron is used in machine parts like gears, rolling mils and crushers and any thing when wear is important.

Grey Cast Iron

Grey cast iron also has carbon percentage of at least 2% but it comes in the form of grahpite. This means it is more ductile, and malleable. Grey cast iron is used in cookware, valves, brake rotors and engine blocks.

Question 9

White cast iron grain structure

Answer 9

(not in orange)

Question 10

Grey cast iron

Answer 10

Question 11

What actually kills you from the asbestos

Answer 11

little fibers stay in your lungs and then your lungs build around the fibers and your tissue scars.