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Terms in this set (38)
2 to 6.67%
Cast iron can have how much carbon content?
2 to 4%
What is the practicale limit of carbon in cast iron?
For excellent casting qualities
Why cast iron is important?
Due to high amount of carbon amount of cementite is also high.
Why cast iron is hard and brittle?
When cast iron is slowly cooled, the cementite decomposes into iron in form of graphite which is called graphitisation.
What is graphitisation?
Cast iron in which large percentage of cementite is decomposed by graphitisation
What is grey cast iron?
Cast iron in which graphitisation has not taken place
What is white cast iron?
White cast iron is comparable in properties to what?
Because it is highly brittle
Why white cast iron is not used in structural parts?
Parts where abrasive wear is present
White cast iron is important for what type of parts?
170 to 345 MPa
What is the range of tensile strength of white cast iron?
What is average value of tensile strength of white cast iron?
350 to 500 BHN
What is the range of hardness of white cast iron?
poor due to high hardness
Machinability is good or poor for white cast iron and why?
How white cast iron parts are finished?
Nickel and Silicon
Name two graphitising elements.
Write the reaction of graphitisation.
By graphitising element and cooling rate
How graphitisation is controlled?
Decreases hardness and increases machinability
What is the effect of presence of graphite in grey cast iron?
The shape of graphite present in cast iron would greatly effect its strength. When it is in a flake-like shape as in grey cast iron, the graphite breaks up the continuity of iron.
Why grey cast iron has good vibration adsorption property?
Flake like shape
How graphite is present in grey cast iron?
Grey cast iron for good vibration absorbing property
What is normally used in machine tools bed and why?
low melting temperature, higher fluidity and negligible shrinkage on cooling.
Three reasons why grey cast iron is used for casting processes?
In which free carbon is present in the form of nodules in the matrix of cementite and ferrite.
What is malleable cast iron?
first chilling so that all white cast iron is formed, followed by a controlled heat-treatment so that the some of the cementite is transformed to ferrite and nodule of free carbon.
How malleable cast iron is produced?
Is malleable cast iron is more ductile than grey cast iron?
Parts with very small section thickness
Malleable cast iron is suitable for what type of parts?
as small, round, and well distributed particle.
How graphite is present in ductile cast iron?
by adding elemental magnesium or calcium or combination of the two element to molten cast iron.
How ductile cast iron can be achieved?
nodular iron, spheroidal graphite or SG iron
What are the other names of ductile cast iron?
0.07 to 0.10% magnesium followed by the addition of ferro-silicon.
What is added in ductile cast iron?
distribution of graphite throughout the metal.
What is the objective of magnesium in ductile cast iron?
better strength to weight ratio, better machinability, higher impact value.
State three good properties of ductile cast iron.
White heart malleable cast iron and black heart malleable cast iron
What are the two types of malleable cast iron?
sand and powdered slag
what is used in heat treating of white heart malleable cast iron?
powdered iron ore
what is used in heat treating of black heart malleable cast iron?
what type of furnace is used for in heat treating of white heart malleable cast iron?
How much time is needed for a complete cycle of white heart malleable cast iron?
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