THE IRON STEEL

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Iron ore from the mine usually is mixed with sand, clay, and other rocks. For the smooth processing of lump ore was broken with the breaking machine, and then sorted the ores and rocks follow the magnetic drum. The next job is to wash and iron ore are classified according to size, fine ores and small items in the kitchen diaglomir sinter or roll up in balls that can be reused as the contents of the kitchen. After iron ore roasting in the kitchen to dry and roasted
elements prone to gas out of iron ore, and was taken to the kitchen high to be processed into pig iron.

In the bowels of the earth where we live it contains many substances that are useful for our daily lives, such as kerosene, gasoline, diesel and other petroleum called. In addition there are also chemical elements that are useful to humans such as iron ore, nickel, copper, uranium, titanium, tin and
many more, along with minerals and rocks. One of the substances contained in the earth that are useful to man is water with the chemical formula H2O, because without water is very difficult to sustain human life. 
Minerals is a material that is widely available in the earth, which has the shape and specific characteristics as well as having a fixed chemical composition. While the stones are a combination of two or more kinds of minerals and do not have a fixed chemical composition. Ore is a mineral or rock containing one kind or several kinds of metal in a considerable percentage to be used as mine. The amount of metal contained in the ore is different.

Metals in a pure state is rarely found in the earth, most of the compounds of oxides, sulfides, carbonates, and sulfates which is a metal ore that needs to be processed into metal materials that are beneficial to humans.

History of the discovery of steel
smelting technique has been around since the days of ancient Egypt in 3000 BC. Even the manufacture of metal jewelry have been around in the days before. The process of hardening the metal by heat treatment was introduced for the manufacture of weapons in the Greco 1000 BC.
made ​​the integration process started there since the 14th century is classified as wrought iron. This process dilakkan by heating a large amount of iron ore in a furnace or furnaces charchoal. With this process the iron ore is reduced to metallic iron sponge is filled with slag which is a mixture of metallic impurities and charcoal ash. Spone iron is removed from the furnace at the time was still shining and covered by a thick slag and iron to strengthen slagnya removed. Receipts of this method of making iron slag produced kandingan sekiar 3 percent and 0.1 percent other impurities. Sometimes produced by this method of producing steel instead of wrought iron. Parapembuat studying iron to make steel by heating wrought iron and charcoal in dar boxes made ​​of clay for a few days. With this process the iron absorbed enough carbon to be a real steel.

After the 14th century furnace or furnaces that use began to increase the size and draft are used for the combustion gases pass through "charge," the mixing of raw material. In the larger furnaces, the iron ore at the top of the furnace will be reduced first reduced to metallic iron and produce lots of carbon as a result of a gas attack in its path. The results of this furnace is pig iron, which is an alloy that melts at low temperatures. Pig iron will dproses further to make steel.

Using modern steelmaking blast furnaces are also used to memurniakan iron by iron maker lamapu. The process of refining molten iron with a blast of air is recognized by the British inventor Sir Henry Bessemer who developed the Bessemer furnace, or converter, in 1855. Since 1960 has produced steel from scrap metal on a small scale in the electric furnace, so-called mini-mills. Mini-mills is the component that is very important for the American steel production. Larger mills are used in steel production from iron ore.

Preparation of Crude Iron
main ingredient for making pig iron are iron ore. Various kinds of iron ore contained in the earth's crust in the form of iron oxide and iron carbonate, the most important of which are as follows.

1. Brown iron stone (2Fe2O3 + 3H2O) with an iron content ranging from 40%.
2. Red granite which is also called hematite (Fe2O3) with k ranging from 50% iron andungan.
3. Stone magnetic iron (Fe2O4) dark green-black, with magnetic iron-containing over 60%.
4. Calcite or iron stone Spat (FeCO3) which is also called sferosiderit with around 40% iron.

Iron ore from the mine usually is mixed with sand, clay, and rocks in the chunk-chunk is not as great. For the smooth processing of iron ore, bricks are solved with a solver engine, then sorted the ores and rocks besih follow the magnetic drum. The next job is to wash and iron ore are classified according to size, fine iron ores and small items in the kitchen diaglomir sinter or roll to form balls that can be reused as the contents of
the kitchen.

After iron ore was roasted in the kitchen to dry and roasted elements prone to gas out of the ore was then taken to a high kitchen is processed into pig iron. High kitchen has two cone-shape standing one above the other on its base. At the top of the stove which extends to the bottom, so that the charge be easily slid down and there is no congestion. Widened the bottom upwards with the intention to remain in charge of this section. The kitchen is made ​​of high fire-resistant composition stone that was given to strengthening the sheath of steel plate construction. From the kitchen filled with filler.Coke in a row is inserted, additional material (limestone) and iron ore. Coking coal is coal that coal is
dry and contains didestilasikan in a very low sulfur. Coke serves as fuel and requires a lot of acidic substances as pengembus. So that the process can go quickly
pengembus air it needs to be heated first air heater in the kitchen

Liquid iron in the kitchen is high, then dicerat and poured into pig iron, in the form of pig iron beams are used as a compound for the manufacture of cast iron (in the kitchen dome), or in a liquid state is moved in the manufacture of steel in the converter or other steel kitchen, such as kitchen Siemen Martin

Limestone as an additive to bind point in coke ash and boulders follow-up to be a slag which can easily be separated from pig iron. Slag itself in the process serves as a protective liquid pig iron from the oxide which may reduce the results obtained for the burning of liquid pig iron. Limestone (CaCO3) decompose followup bind stones and other elements.

Process in Higher kitchen
from the kitchen of high principle is the principle of reduction. In this process of carbon monoxide can absorb oxygen from the iron bonds of oxygen at high temperatures. At high temperature combustion + 18 000 C with hot air, then the resulting temperature reduction that can hold it.
To avoid pembuntuan because the process is given limestone as an additive. Additional material in an acidic iron ore and base properties have otherwise given the additional material is alkaline when iron ore is acidic. Gas formed in the kitchen the next high flow out through
the top of the d 's into the air heater. Slag is trickling down to protect the pig iron from the oxide by the hot air is entered, the slag is then separated.

Reduction process in the high kitchen took place as follows:
Substance of coking coal burned by the reaction: C + O2 -------> CO2 portion of CO2 along with carbon to form a substance that was at the top of the more CO gas. CO2 + C --------> 2CO

At the height of the kitchen at 3000 to 8000 C temperature of the iron oxide is converted into higher oxides are lower by indirect reduction with CO according to the principle:
Fe2O3 + CO ---------> CO2 + 2FeO

At the time of the last cargo down to the bottom and there was no immediate reduction according to the principle:
FeO + CO -----------> CO2 + FeO

This reduction is called indirect because it is not pure carbon but rather a reduction of carbon compounds with oxygen.whereas direct reduction occurs in the hottest part of the kitchen, which is directly above the pipe pengembus. This reduction takes place as follows.
FeO + C -------> Fe + CO

CO is formed that is up to the top to hold the reduction was not immediate. Every 4 to 6 hours of high dicerat kitchen, first issued teraknya and then iron. Iron out of the kitchen is called the iron
rough or crude iron used to make steel on steel processing kitchen or poured into cast blocks sent to factories as raw material for steel making. Iron dicerat liquid pig iron and cast into the form pig iron beams are used as materials for the manufacture of cast iron ancuran (in the kitchen dome) or still in the liquid state is moved in the manufacture of steel (kitchen Siemen Martin). Slag is high out of the kitchen can also be utilized as a material of sand-making slag or slag wool as insulating material or as a mixture of cement.

Molten iron produced from the kitchen before it is poured into the high beams as a rough besin ancuran material in the foundry plant, should be mixed in advance in the tub mixer for uniform quality and composition. A bath of molten pig iron mixer collected from a variety of high existing kitchen to get the same molten pig iron and evenly. To produce pig iron which contains a little sulfur in the mixing tub is heated again by using high gas kitchen.

Preparation of Crude Steel from Iron
Pig Iron as a result of the high kitchen still contains many elements that are not suitable for construction materials, substances such as charcoal (carbon) that is too high, phosphorus, sulfur, silisium and so on. These elements
should be as low as possible in various ways.

To reduce levels of carbon and other additional elements of pig iron used in the following way. Converter process:
a. Bessemer process for pig iron with low phosphorus levels. 
b. Thomas process for pig iron with a high phosphorus levels.
c. Oxide process, the LD, and Oberhauser Kaldo. Process Martin (Martin Siemen kitchen) a. Martin acid process for pig iron with low phosphorus levels. b. Martin process for pig iron base with high phosphorus levels. Kitchen Electrical steel mixture to a. Kitchen electric arc flame. b. Induction electric kitchen.

In general, the converter is working:
a. Coke heated to a temperature of 15000C.
b. Tilted to include raw material of steel (1/8 of the volume of the converter). 
c. Converter is re-established.
d. Exhaled air with a pressure of 1.5 to 2 atm with a compressor.
e. After 20-25 minutes the converter turned upside down to release the results.

General overview of steelmaking summarized in the figure above. At first, the raw material is obtained from iron ore mined. These typically have iron ore Fe content (low iron). With the beneficiation process to have a higher Fe content, it can be in the form of pellets or sinter. High Fe content could be above 90%. After iron ore reached a high Fe content, the next process is to make the smelting of iron into steel.

In general, there are two methods of fusion when viewed from the process. First, using a blast furnace that uses coal as its fuel. The second is the direct reduction process that uses natural gas as reduktornya to then proceed to the furnace (usually electric arc furnace). During this melting process, the carbon content is reduced to below 2% and alloying elements are added to give the steel the desired properties. The resulting product is a liquid steel. The next process is the function to change the casting of molten steel into a solid form of thick steel sheets which are usually called a slab.

The next process is the physical change is a thick steel sheet becomes thinner and then turn it again into a more specific according to their usefulness.

Well, that's an overview of steelmaking. Simple as that which I write here. But in fact, quite complicated because it involves the parameters of the specific processes and controls should be tight against the steel making process.

(A). Bessemer process
Bessemer Converter is a steel vessel with fire-resistant layer of rock that are acidic. On top of it open while at the bottom there is a number of holes for air ducts. This vessel can diguling-roll. Korvertor Bessemer filled with a lot of gray pig iron containing silisium. Silisium and manganese on fire the first time, after which a new substance that burned charcoal. At the time of the air flowing through the air pig iron burned carbon and additional mixed so that the kitchen was still in a state diluted.

After approximately 20 minutes, all substances have been burning charcoal and slag are going out. Given the need carbo steel of 0.0 to 1.7%, then the processing time is too much missing on fire, it must ditambahy deficiency in the form of iron that contains carbon. In this way the carbon content increased. formed from the oxidation of iron and acid-containing substances can be reduced by iron-containing manganese.

The air was blown into the vessel earlier in order to get a good mix. Then the slag discharged again and then the charge is poured into a pouring pot. In the Bessemer process using pig iron containing phosphorus and low sulfur content of phosphorus and sulfur, but still remains rather high because the two elements in the process does not burn at all. The results of the so-called Bessemer converter Bessemer steel is widely used for construction materials. Bessemer process is also called acid process because it is acidic and its cargo hold fire stones are also acidic. When used charge an alkaline rock layer will be damaged due to salting reaction.

(B). Thomas process
is also called the converter Converter Thomas basa basa and the process is a process, because the fire-resistant stone is alkaline and is used to process pig iron which is alkaline. Thomas is a charge converter pig iron
that contains a lot of white phosphorus. Combustion process similar to the process at Bessemer converter, is only
just at the Thomas phosphor burn after burning charcoal substance. Air drainage is constantly being made ​​because the iron itself will burn. Prevention of burning was done by assuming the process is complete, although still high phosphorus content.

To bind phosphorus formed in this process is given additional material to be limestone slag. An alkaline slag can be utilized as a fertilizer known as artificial phosphate fertilizers. The results that came out of the converter process called Thomas Thomas steel used as construction materials and boiler plate.

(C). Martin process
another process for making steel from pig iron materials is used kitchen Siemens Martin is often called the Martin. It consists of a kitchen stove to the melted material and typically use four rooms as gas heaters and air. In this process the charge used scrap metal that is mixed with pig iron so as to produce steel with better quality when compared with Bessemer steel and Thomas.

Gas will be burned with air to flow into the combustion chambers through the fire-resistant stone that is heated to a temperature of 600 to 9000 C. thus the flame has a high temperature, approximately 18 000 C. combustion gases are moving outward into space gives the second heat, using hot tap regulator of the gas and combustion air into the room is alternately heated and cooled. The fuel used was a high kitchen gas, oil digaskan (stookolie) and also gas generator. On the carbon combustion CO and CO2 gas occurs that rises to the top and the resulting liquid is turbulent, thus will occur hubungann a close connection between the fire with the charge material is inserted high into the kitchen. Additional material will be immiscible with oxygen to form liquid slag cover that protects the liquid from further oxide. After the process runs for 6 hours, slag is removed by tilting the kitchen and then the molten steel can be dicerat. The end result of a process called Martin Martin steel. Steel is good quality because of its composition can be determined by carefully regulated and the process lasted rather longer.

Layer at the Martin kitchen can be acid or alkaline depending on the rough iron containing phosphorus or less. Teradi acid Martin process pig iron when treating an acidic or low phosphorus and vice versa Martin said the base when the charge is alkaline and contains high phosphorus. Advantages of the process of disbanding Martin and Thomas Bessemer process
is as follows:

1. A longer process that can produce a better arrangement with the way the experiments.
2. Elements and unwanted impurities can be avoided or cleaned.
3. The addition of scrap iron and other additives at the end of the process led to its composition can be carefully managed.

In addition to the above advantages and because of the combustion air flow over the liquid containing the final result will be a little weak acids and substances. Martin alkaline process usually still contain some impurities such as oxygen, sulfur, phosphorus and so on. While the levels of acid Martin process impurities is smaller

(D). The process of oxygen
converter process is a more modern is the process of oxygen, the process is using the material composition of pig iron that has done less well when converters Bessemer and Thomas. Here pure oxygen is blown over the liquid and sometimes also into the liquid iron, so that carbon, silisium, manganese and so on fire.

The burning of these elements are accommodated by additional material limestone and slag are bound to be floating on the liquid iron. Combustion process with carbon acids occurs at very high heat, it is necessary to provide additional cooling by way of scrap steel. The end result of this process is oxy-quality steel is very good because the bad influence of the air element does not exist. Therefore, the steel used oxy well as materials for construction and machinery components, such as shafts, bolts, pegs, shaft drive and others.

The advantage of the oxygen is as follows:

1. Relatively short processing time.
2. The result of phosphorus (P) and sulfur (S) is low.
3. The results produced relatively more in the same tempo than other processes.
4. Production costs per ton of steel is more expensive.

(E). Hoecsch process
Hoecsch process is a refinement of the Martin. The trick is after a charge in the kitchen Siemens Martin melt and then immediately removed and placed in an open cauldron for burning phosphorus and sulfur. While burning conducted Siemens Martin cleaned the kitchen floor kitchen and then sprinkled with powdered iron ore (Fe2O3 or Fe3O4). When finished hold the burning phosphorus, sulfur and iron in the liquid in the pot was put back into the kitchen Siemens Martin to complete the combustion
of other elements that have not been lost, especially carbon. Once the process is considered complete carbon combustion, slag happens next issued accommodated in a pot of molten steel foundry to cast or molded into a block castings.

(F). Bertrand process Thield
process uses two pieces of Martin Siemens kitchen. In the kitchen the first conducted pemijaran to separate and burning phosphorus in the kitchen while the second is filled with molten iron from the kitchen of the first results after teraknya issued. Process in which the second kitchen was also given a new addition to iron ore.

(G). Duplex Process
This process is done by first decarbonize converter-converter which is purified in the kitchen and Siemens Martin. Duplex process is mainly carried by the steel mills near the company's high kitchen. Once the process is high in the kitchen (after teraknya omitted) liquid pig iron was introduced into the converter (Bessemer or Thomas) and mixed with limestone and steel used in the desired amount. Pengembusan air in the converter made ​​up into a low phosphorus content of about 1 to 1.5%, coupled with the coke that has been milled then move it into the kitchen Siemens Martin.

(H). Thalbot process
Thalbot process is done using Siemens Martin kitchen that can be twisted around and dijungkitkan. After pemijaran Martin in the kitchen, most of the liquid is poured into a panic and pour into the kitchen as he added pig iron, iron ore and limestone.

The next process is to keep the liquid cast iron in the panic was not the case of oxidation, meaning that seek rapid cooling. As a result of this is the way the results obtained in each process of a kitchen is not the same quality. Steel produced from the Thalbot is ordinary steel as the result of the Bessemer and Thomas converters.

(I). Process Electric Kitchen
Kitchen electricity used to manufacture steel that is resistant to high temperatures. This kitchen has the following advantages,

1. The amount of heat required can be arranged as well as possible.
2. Effect of oxygen practically does not exist.
3. The composition of the iron is not affected by power surges.

While the downside is the price of electricity is expensive. Electric kitchen is divided into two groups: the kitchen and kitchen electric arc electric light induction.

(J). Stir in the process of Kitchen
Kitchen stirring is the conventional way of making steel by melting pig iron in the kitchen flames together with the slag (FeO) to obtain acid. By way of poking around with an iron rod and inserted into the bottom surface of the air then there is a time software that contains a lot of steel slag.

If the clumps are made ​​in the kitchen has reached approximately 60 kg removed, then the step is removing slag hereinafter by way of forge or pressed. In this stirring process more
handwork involved and the small production capacity is viewed in this way is inefficient and rarely used in steel mills.

Carbon steel 
Carbon steel is carbon steel containing up to 1.7%. Carbon steels are classified into three groups based on the amount of carbon contained in steel, namely:

a. Low carbon steel.
steel containing carbon of 0.10 s / d 0.30%. Low carbon steel in the trade is made ​​in the form of plates, bars for forging, machining, and others.

b. Carbon steel is.
carbon steel contains between 0.30 s / d 0.60%. Carbon steel is normally used in the trade as a means of tools, bolts, crankshaft, gears, vise, springs, and others.

c. High carbon steel.
carbon steel containing between 0.70 s / d 1.5%. Carbon steel is widely used for the manufacture of construction equipment associated with high heat or in use will receive and experience the heat, such as foundation, hammers, saws, chisels, files, drill bits, ball bearings, and so forth.

Based on the use of steel can be classified into two groups, namely steel and tool steel construction. Steel construction including the construction of buildings and construction machinery. Steel building construction generally contains carbon up to 0.3% in tensile strength and low stretch limits and can not be hardened. While the steel machines generally have a carbon content ranging from 0.3 s / d 0.6%, has a hardness
greater tensile strength and tensile limit is rather high and can be hardened.

The second group is classified as steel on steel is no longer a combined, low alloy steel and high alloy steels, namely:
a. Steel which is combined contain 0.06 s / d 1.5% carbon, with a little manganese (Mn), silisium (Si), phosphorus (P) and sulfur (S).
b. Low alloy steel containing 0.06 s / d 1.5% with an additional 5% carbon alloy material.
c. High alloy steel containing 0.03 s / d 2.2% carbon by more than one alloy materials as much as 5% or more.

Steel Construction
Steel construction used for building construction and manufacturing of engine parts. Based on the mixture and the manufacturing process, the steel construction can be divided into:
a. plain carbon steel.
b. Construction of high quality steel.
c. Special steel

The steel construction dikelompokakan in three types consist of: 
a. General construction steel.
steel construction consisting of common types of carbon steel and high quality steel combined. The use of steel is based on the consideration of the minimum tensile stress is high enough. This steel is widely used in building construction, bridge, engine shaft and gears.

Publicly traded steel construction in the two types are usually distinguished by the quality of the provision of the code numbers 2 and 3.
Example: St. 44-2 for the high quality.
St. 44-3 for a special quality (specifically).

b. Automatic steel. 
Steel automaton consists of high quality steel that is not combined and low-alloy steel tinggin quality with high levels of sulfur (S) and phosphorus (P) is high. This steel contains 0.07 s / d 0.065% carbon, 0.18 s / d 0.4% sulfur, 0.6 s / d 1.5% manganese, and 0.05 s / d 0.4% silisium. For the purposes of smoothing the surfaces were added to the
lead (Pb) 0.15 s / d 0.3%. Because they contain sulfur (S) and phosphorus (P) is high enough, then the automaton is not very good steel for welding jobs.

c. Case hardening steel.
steel case hardening is obtained by placing a soft steel between the carbon-rich material and heating it up above the upper critical temperature (900 - 9500 C) in a long time to get
a lot of the surface layer containing carbon.

Case hardening steels are composed of high quality steel that is not combined and special steel that is not combined or combined. So that the workpiece remains tough, grown on the surface of the carbon content of Genesis which has carbonised bodies had ranged between 0.6 to 0.9%.

Tool steel 
tool steel is widely used for materials to make tools, such as seals, caliber, as well as cutting tools. Tool steels are classified based on:
1. Alloy state: not coupled, low alloy and high alloy.
2. Cooling agents: water, oil, and air.
3. The hardening process: hot and cold work processing.

The properties of alloy tool steel without the most important are as
follows:
a. Carbon content between 0.35 to 1.6%.
b. Hardening temperature of 750 - 8500 C.
c. Tempering temperature of 100 - 3000 C.
d. Working temperatures up to 2000 C.

Pour steel
Steel castings are poured steel in some form, once the process is complete penungan, castings heated up to temperatures between 800 - 9000 C and then rapidly cooled at a temperature of 7000 C and finally cooled slowly to obtain a fine grain structure. Cast steel is widely used for the manufacture of large machines, such as a home turbine, turbine blades, and as part of the motor fuel.

Carbon content of steel castings are usually lower than the carbon content of cast iron and are usually less than 1.0% C.as additional elements other than carbon, cast steel containing 0.20 to 0.70% Si, 0.5 - 1.0% Mn, phosphorus
below 0.06% and 0.06% sulfur below. The microstructure of cast steel having carbon content of less than 0.8% consists of ferrite and pearlite, the higher carbon content will increase the amount of pearlite. If the carbon content greater than 0.8%, this would cast steel consists of pearlite and cementite is a separate, higher carbon content will increase the amount of cementite.

Typical properties of cast steel is the carbon content increases kalu strength increases, while its extension increases and decreases the value of impact resistant, and difficult in the weld. The addition of manganese would give a higher tensile strength. Normalizing will provide fine grain and increases strength and the tensile limit its appeal. Repair properties of cast steel will be very pronounced when the carbon content is higher. If the cast steel at a temperature of 6500 C ditemper after softened, then the elastic limit and strength of its appeal will decrease while the elongation and reduction area better