Iron Occurrence Use and alloys – Metalurgy

Occurrence

Iron ore are hematite (ferric oxide, Fe₂O₃), magnetite (triiron tetroxide, Fe₃O₄), limonite (hydrated ferric oxide hydroxide, FeO(OH)∙nH₂O), and siderite (ferrous carbonate, FeCO₃).

Different types of iron and its material properties

Pig Iron and its properties:

• Pig Iron is a basic raw material for all irons and produced from a blast furnace.
• It contains Carbon percentage equal to 3-4%(Si 0.5 to 1.2%)
• not suitable for any commercial application. Further sent for steel making or foundries.
• Pig Iron from ore contains three basic forms of Iron:

1. Cast iron (Made from Cupola furnace)
2. Wrought Iron (Made from Pudding furnace)
3. Steel (Made from Bessemer converter)

Wrought Iron and its properties:

• Wrought Iron is a mechanical mixture of pure iron and silicate slag
• Its Carbon percentage is 0.1% to 0.15%
• Wrought Iron is never cast or difficult to cast
• It is having Tensile strength: 3380-3500 kg per square centimetre and 2530-2670 kg per square centimetre in a transverse direction
• Wrought Iron’s melting point: 1510 degree C, Weight – 7680 kg per meter cube.

Cast Iron and its properties:

• Cast Iron is having Carbon percentage: 2 % to 4 %
• Cast Iron having material properties like High yield strength, ease of machinability, corrosion resistance and high young modulus
• It is having low coefficient of thermal expansion and high wear resistance & damping vibration.
• Cast Iron is used to make Crank-shaft, railroad, universal joint etc.

Steel and its properties

Steel is an alloy of iron with typically a few tenths of a percent of carbon to improve its strength and fracture resistance compared to iron. Many other elements may be present or added. Stainless steels that are corrosion- and oxidation-resistant need typically an additional 11% chromium. Because of its high tensile strength and low cost, steel is used in buildings, infrastructure, tools, ships, trains, cars, machines, electrical appliances, and weapons. Iron is the base metal of steel.

Use

• The average quantity of iron in the human body is about 4.5 grams (about 0.004 percent), of which approximately 65 percent is in the form of hemoglobin, which transports molecular oxygen from the lungs throughout the body; 1 percent in the various enzymes that control intracellular oxidation; and most of the rest stored in the body (liver, spleen, bone marrow) for future conversion to hemoglobin.
• Special Steels

Alloys of iron

Nickel Steel (Ni 3.25%)

Stainless Steel (Cr 11 to 15%)