Heat treatment in metallurgy

In metallurgy, heat treatment is defined as the combination of heating and cooling operations carried out on a metal or alloy in the solid state. Heat treatment helps to achieve desired microstructure and properties. For steel, a wide range of mechanical properties can be accomplished by proper heat treatments. Heat treatment helps to improve mechanical properties such as tensile strength, impact resistance and ductility. It also improves magnetic and electrical properties. By heat treatment we can increase wear resistance, abrasion etc. Heat treatment also helps in improving machinability and refining grains. By suitable heat treatment, we can produce hard surfaces and soft interior portions. There are two types of heat treatment processes. They are full heat treatment and surface heat treatment. Recrystallization annealing, full annealing, partial annealing, process annealing, spheroidising annealing, normalizing, hardening, austempering and mastempering comes in the category of full heat treatment. Surface heat treatment includes pack carburizing, liquid carburizing, gas carburizing, cyaniding, nitriding, carbo-nitriding, flame hardening and induction hardening. Some advanced techniques of heat treatment are ion nitriding, plasma carburizing, electron beam hardening and laser hardening.

Aeroplane component parts

Aeroplane is slowly becoming a common mode of transportation after the global economic reforms. The main components of an aeroplane are engine, propeller, fuselage, wings, three controls, flaps and tricycle under-carriage. Engine provides proper propelling force. There exist four types of engines. They are piston engine, rocket, turbojet and turbofan. A piston engine is powered by gasoline fed reciprocating engine which is driven by propeller. Propeller consists of two or more blades which are driven round in a circular path. Fuselage is the main part of the aircraft where power plant, fuel, cockpit, passenger space, cargo etc. are accommodated. Wings are used to support the machine in the air when the engine has given it the necessary forward speed. Three controls namely elevator, rudder and aileron are required for the fine controlling of the aeroplane. Elevator and rudder are also known as empennagewhich are located at the tail end of the fuselage. Aileron is a binged flap which is fixed in the trailing edge of the wing near the wing tip. Pilot can easily operate these control units from his cabin. Flaps are used to increase the lift on aerofoils. Tricycle under carriage supports the aircraft whenever it is in contact with the ground.