Aluminium and its Alloys

The non-ferrous metals are those which contain a metal other than iron as their chief constituent. The non-ferrous metals are usually employed in industry due to the following characteristics: Easy to fabricate i.e., casting, rolling, forging, welding and machining, High resistance to corrosion, Very good electrical and thermal conductivity, Low weight and attractive appearance. The various non-ferrous metals used in engineering practice are aluminium, copper, lead, tin. Zinc, nickel etc, and their alloys. Aluminium The chief source of Aluminium is a clayey mineral called ‘Bauxite’, which is a hydrated aluminium…

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Copper and Its Alloys

Copper is one of the most widely used non-ferrous metals in industry. It is not found in pure state from under the earth. It occurs in some minerals such as copper glance (Cu2S), copper pyrites (CuFeS2)’ malachite (CuCO3.CuO2H2) and azurite (3CuCO3.CuO2). Properties and Uses It is a soft, malleable and ductile metal with a reddish-brown appearance. Its specific gravity is 8.9 and melting point is 1083°C. It is a good conductor of electricity. It is largely used in making electric cables and wires, for electric machinery and appliances. It is…

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Zinc Metal and its Alloys

The chief ores of Zinc are zinc blende (zinc sulphide) and calamine (zinc carbonate). In the extraction of the metal, the ore is first roasted in a reverberatory furnace to convert the sulphide to oxide, and in the case of calamine, to drive off carbonic acid and water. The roasted ore is then reduced either in a furnace or by electrolysis process. Zinc is fairly heavy; bluish-white metal used principally because of its low cost, corrosion resistance and alloying properties. The melting point of Zinc is 4190C. The protection of…

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Nickel and its Alloys

Nickel is obtained commercially from oxide ores, arsenical ores, and ores of Copper, Manganese and Iron, at least 85 percent of all nickel production is obtained from Sulphide ores. Pure nickel is tough silver-coloured metal, rather harder than Copper and have about the same strength, but possessing somewhat less ductility. It closely resembles Iron in several of its properties. It is malleable, weldable, and perceptibly magnetic. But unlike Iron, it is little affected by dilute acids. It is far less readily oxidisable, and deteriorates much less rapidly under atmospheric influences…

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Engineering 

Titanium & Zirconium Alloys

Titanium is a chemical element with the symbol Ti and atomic number 22. Sometimes called the “space age metal”, it has a low density and is a strong, lustrous, corrosion-resistant (including sea water and chlorine) with a silver color. Titanium can be alloyed with Iron, Aluminium, Vanadium, and Molybdenum to produce strong lightweight alloys for aerospace (jet engines, missiles, and spacecraft), military, industrial process (chemicals and petro-chemicals, desalination plants, paper industry), automotive, orthopedic implants, and other applications Property A metallic element, Titanium is recognized for its high strength-to-weight ratio It…

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Engineering 

Introduction to Heat Treatment

Heat treatment is an operation or combination of operations, involving heating and cooling of a metal or alloy in the solid state for the purpose of changing the properties of the metal. Heat treatment consists of three phases. (a) Heating of the metal. (b) Soaking of the heat into metal. (c) Cooling of the metal. Purpose of Heat Treatment The purpose of heat treatment is as follows: (a) To improve machinability. (b) To improve mechanical properties, e.g., tensile strength, ductility, hardness and shock resistance. (c) To relieve the stress induced…

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Furnaces Used for Heat Treatment

Heat treatment furnace may be defined as a refractory-lined chamber in which the metal part to be heat-treated, is heated to the required temperature. Usually a heat-treatment furnace is a box-like structure i.e., a steel shell with an access door, a refractory lining, temperature controls and indicators. Furnaces used for heat treatment are classified as: (a)    Hearth furnace             (i)         Stationary hearth furnace             (ii)        Movable hearth furnace (b)    Bath furnace             (i)         Salt bath             (ii)        Lead bath             (iii)       Oil bath Stationary Hearth Furnaces        These are of…

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Types of Heat Treatment

Heat treatment is defined as an operation or combination of operations, involving heating and cooling of a metal or alloy in the solid state to obtain desirable properties. Heat treatment consists of three phases. (a)        Heating of the metal (b)       Soaking of the heat into metal (c)        Cooling of the metal Heating.       Heating temperature of metal for the purpose of heat treatment depends upon its grade, grain size, type and shape of a metal or alloy. Generally, the metal is never heated much beyond its upper critical temperature. Plastic…

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Engineering 

Various Types of Heat Treatment Processes

Various types of heat treatment processes are: (a) Annealing (b) Normalizing (c) Hardening (d) Tempering (e) Refining Annealing Annealing is one of the most important heat treatment operation applied to steel. It is the process of heating the steel in a furnace to a point not exceeding 50° above its upper critical point and maintaining the steel at that temperature for a considerable time (30-60 minutes) to convert the whole steel to austenite. Steel is allowed to cool down slowly through a medium of hot sand, hot ashes or hot…

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