Topic: Ferrous & non Ferrous Metals;

 

Ferrous Metals:

 

Ferrous metals are iron base metals which include all variety of pig iron, cast iron wrought iron and steels. The ferrous metals are those which have iron as their main constituents. The ferrous metals commonly used in engineering practice are cast iron, wrought iron, steel and alloy steels. The basic principal raw material for all ferrous metals is pig iron which is obtained by smelting iron ore, coke and limestone, in the blast furnace. The principal iron ores with their metallic contents

Main Types of Iron

1. Pig iron

2. Cast iron

  • White cast iron
  • Gray cast iron
  • Malleable cast iron
  • Ductile cast iron
  • Meehanite cast iron
  • Alloy cast iron

3. Wrought iron
4. Steel

  • Plain carbon steels

                    a. Dead Carbon steels
                    b. Low Carbon steels
                    c. Medium Carbon steels
                    d. High Carbon steels

  • Alloy steels

                       a. High speed steel
                        b.Stainless steel
Some important ferrous metals, their extraction, composition, properties and their common applications are discussed in detail as under.

 

Non-Ferrous metals:  Manufacture The bauxite is purified and then dissolved in fused cryolite (double fluoride of aluminium and sodium). The aluminium is then separated from this solution by electrolysis at about 910°C.


Properties: Pure aluminium has silvery color and luster. It is ductile, malleable and very good conductor of heat and electricity. It has a very high resistance to corrosion than the ordinary steel. Its specific gravity is 2.7 and melting point is 658°C. Its tensile strength varies from 95 to 157 MN/m2. In proportion to its weight it is quite strong. In its pure state the metal would be weak and soft for most purposes, but when mixed with small amounts of other alloys, it becomes hard and rigid. It may be blanked, formed, drawn, turned, cast, forged and die cast. Its good electrical conductivity is an important property and is broadly used for overhead cables. It forms useful alloys with iron, copper, zinc and other metals.

 


Applications: It is mainly used in aircraft and automobile parts where saving of weight is an advantage. The high resistance to corrosion and its non-toxicity make it a useful metal for cooking utensils under ordinary conditions. Aluminium metal of high purity has got high reflecting power in the form of sheets and is, therefore, widely used for reflectors, mirrors and telescopes. It is used in making furniture, doors and window components, rail road, trolley cars, automobile bodies and pistons, electrical cables, rivets, kitchen utensils and collapsible tubes for pastes. Aluminium foil is used as silver paper for food packing etc. In a finely divided flake form, aluminium is employed as a pigment in paint. It is a cheap and very important non ferrous metal used for making cooking utensils.

 

 


Aluminium alloys: The aluminium may be easily alloyed with other elements like copper, magnesium, zinc, manganese, silicon and nickel to improve various properties. The addition of small quantities of alloying elements into other metals helps to converts the soft and weak metal into hard and strong metal, while still retaining its light weight. Various aluminium alloys are

 

  • Duralumin,
  • Y-alloy,
  • Magnalium and
  • Hindalium ,   These alloys are discussed as below:

 

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