1 Flashcards
How is pig iron produced?
By smelting iron ore in a blast furnace
Steel is made from? And how is steel made?
Steel is made from PIG IRON / and can be made using the BASIC OXYGEN PROCESS OR THE ELECTRIC FURNACE PROCESS
The charge in a basic oxygen furnace consists off?
40% scrap steel, lime and molten PIG IRON . OXYGEN IS THEN BLOWN AT THE SURFACE OF THE MOLTEN CHARGE FROM A WATER COOLED LANCE
How does electric ark steel making work? And what’s its advantage?
The heat required to melt the charge is
Produced by electric arcs struck between carbon electrodes and the steel.
The advantage of the electric furnace is the imperial is in the air are excluded.
Low carbon or mild steel contains?
Medium carbon steel contains?
High carbon steel contains
0.25% carbon
0.25% to 0.7%
0.7% to 1.5%
Ferrite is?
Cementite is?
Ferrite is Soft ductile and not very strong
(Iron carbide)Cementite Is very hard and brittle
What’s so important about the carbon content 0.83%
Purely pearlite and only one arrest point.
What happens when you go above or below 0.83% carbon
Above = Cementite
Below = ferrite
TO ARREST POINTS
What happens when arrest points are hit?
Temp stops going up, heat’s absorbed which brings structural change
4 types of heat treatment
Tempering
Annealing
Normalising
Hardening
What type of treatment is normalising?
Restores the crytalline structure
What does tempering do?
Takes away hardness to increase toughness and decrease brittleness
What does annealing do?
Annealing is a softening heat treatment. It’s heated to its upper critical limit, then allowed to cool slowly in a furnace
Normalising?
Heated up to the critical point then allowed to cool in still air
Hardening
Heated to upper critical point then immediately quenched in water or oil
