Iron is a metal which has carbon as it major continent,Steel is the allow of carbon and Iron .
Type of iron
1. Cast iron: is an Iron or a ferrous alloy which has be heated to be liquefied then pour into mold to solidify. A cast iron has different types:
White cast iron
Grey cast iron
Malleable cast iron
White cast iron has carbide impurities
Production of cast iron
Cast iron is made by the melting of pig iron often along with substantial quantities of scrap steel, limestone and carbon and also taking various steps removal impurities that comes with the Production process
Grey cast iron
It is characterizes by graphics micro structures which caused fracture of the material to have a Grey appearance. It has lower shock resistance and tensile strength than steel .it is used for housing where the stiffness or the component is more important than it tensile strength
Example of where it is used
Internal combustion engine cylinder clock
Pump housing
Valve bodies
Electrical boxes
Decorative casting
Merits
1. It has high thermal conductive
2. It has a relatively low cost and good machine ability
3. It has less solidification shirnkage
4. It has good wear resistant
5. The silicon content promote it corrosion in resistance and increase fluidity when casting.
Dis merits
It has low tensile strength and ductility
White cast iron
This displace white fracture surface due to the present of clementine. It has low silicon and a faster cooler rate since cable make a Lary fracture of the material. White cast iron can be reasonable be classified as a cement. White cast iron is too brittle for use in many structural components resistance and it also had a relative low cost
Application of White cast iron includes
1. They wear surface of slurry pumps
2. Shell liners and lifter bars of auto-generated grinding mills.
Malleable cast iron
Start a White iron casting that is the heat-treated as about 900⁰c. Graphite separate out much more lower in this case do that surface tension has time to form it into spherical particle than flakes.they has blunt boundaries which alleviate the strength concentration problem faced by grey cast iron. Malleable cast iron has similar properties to those of mild steel
Three basic types of Malleable cast iron
1. Black heart Malleable cast iron
2. White heart Malleable cast iron
3. Pearlite Malleable cast iron
Malleable iron is a good choice for small casting within thin cross section. It also exhibit better fracture toughness properties in low temperatures of environment due it lower silicon content.
After the casting and heat treating process Malleable iron can be shaped through cold working such as stamping for straightened,bleeding or coining operation. This is possible due to Malleable iron. Desirable properties was being less strain rate sensitivity than other material
Uses of Malleable cast iron
It is often use for small casting requiring good tensile strength and ability for flex without breaking. It uses include electrical fitting, hand tools, pipe fitting, washer (fence fitting), power line hardware,farm equipment and machine parts.
Annealing
Is a heat treating process that changes the physical and some time also the chemical properties of a substance to increase ductility and reduce the hardness making it more workability. Annealing process required the material above its recrystallization temperature for a set amount of time before cooling. The cooling rate depends on the amount of depends of the type of metal be annealed. The heating process cause the atoms to magin star is a lattice and the number of dislocation reduces which leads to change ductility and hardness . The crystal grain size and phrase composition depends on the heating and cooling rate and this tone determines the material properties.
Annealing occurs in three stages
1. Recovery stage: this is the stage where the furriance or heating devices is used to raise the temperature of the material to such a point that the internal stress are relived
2. Recrystallization stage: this is heating the material above it recrystallization temperature bet below it melting point. It causes new grain to form without any residual stress.
3. Grain growth stage: cooling the material at a specific rate causes the new grain to develop after which the material will be more workable.
When is annealing required and why is it important
Annealing is used to reverse the effects of work hardening which can occur during process such as blending, cold forming and drawing. If the material becomes too hard ,it can make working impossible thus leading to cracking.
Annealing also removes stressed that can occur when weld sodifiers ,while steel and alloys steel annealing Is common, other metals can also benefit from this process such as brass,Cooper.
Metal fabricator use annealing to help create complex parts by keeping the material workable by returning them close together per work state.
Type of annealing
1. The full or complete annealing
2. Process annealing
3. Isothermal annealing
4. Incomplete annealing
5. Diffusion annealing
6. Spherification annealing
Merits
1. It improves the workability of the material
2. It increase toughness
3. It reduces hardness
4. It increase ductility and machine ability of metal
Dis Merits
1. It is a time consuming produce depending on the material being annealed
2. Material with high temperatures requirement can take long time to coil .
Aluminum alloy
Are alloy which are Aluminum is the perdiominat metal. The typical alloys elements are tin,zinc, copper ,magnesium, silicon and magnesium.
Aluminum is the world's most abundant and it is the third most common element comprising 8% earth crust. the versatility of aluminum make it the most widely used metal after steel.
Some aluminum alloy include
Dualism
Magnesium
Hiradalium
Properties of aluminum
1. Low density
2. High strength to weight ration
3. Resilient
4. Good corrosion resistance
5. High Malleability and machine ability
6. Good thermal and electrical conductivity
7. Non magnetic
8. Reflectivity
9. Non toxic
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