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Welding is usually regarded as a joining process in which the work pieces are in atomic contact often with a filler metal with broadly similar properties. Hence soldering and brazing are excluded but both solid state and fusion welding are included.

The basic substance used to make both steel and cast iron (gray and malleable) is iron. It is used in the form of pig iron. Iron is produced form iron ore that occurs chiefly in nature as an oxide, the two most important oxides being hematite and magnetite.

Wrought iron is almost pure iron. It is made from pig iron in a puddling Furnace and has a carbon content of less than 0.08 percent. Carbon and other elements present in pig iron are taken out, leaving almost pure iron.

Useful Formula Carbon Equivalent :CE = C + Mn/6 + (Cr+Mo-V)/5 + (Ni+CU)/15 % Delta Ferrite : % F = 3[Cr - 0.93 Ni -6.7] Heat input :H(KJ/mm) = ( V x 1 x 60 ) / ( V5 x 1000)

Steel forgings may be of carbon or alloy steels. Alloy steel forgings are harder and more brittle than low carbon steels.

Aluminum is used as a deoxidizer and alloying agent in the manufacture of steel. Castings, pistons, torque converter pump housings, aircraft structures, kitchen utensils, railways cars, and transmission lines are made of aluminum.

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Lack of fusion/penetration cause by : Too large an electrode for weld preparation. Incorrect angle of electrode for weld preparation. Current too low. Travel speed too high etc

Too short an arc length will cause irregular piling of the weld metal. The ripples will be irregular in height and width.

The identification of covered electrodes in EN 499 is as follows:Covered electrode, strength, Toughness, Chemical composition, covering, efficiency, positional capability, low hydrogen potential

Manual metal arc (MMA) welding, also known as shielded metal arc welding (SMAW), stick, and electric arc welding is a constant current drooping arc process.

this is often referred to as the 'self-adjusting arc'. Metal Inert Gas (MIG) welding is a 'flat' arc process (constant) voltage. Also known as Metal Active Gas (MAG); CO2; Metal-arc Gas Shielded, flux core and GMAW (US).

In DC welding the electrode usually has negative polarity, which reduces the risk of overheating which may otherwise occur with electrode positive. The ionized gas or plasma stream can attain a temperature of several thousand degrees centigrade.

Tungsten inert gas welding is a constant current drooping arc process. It is also known as TIG, gas tungsten arc welding - GTAW, wolfram inert gas - WIG, and under the trade names of argon arc and heli arc.

Positional welding (other than flat) often relies on arc force and surface tension effect; therefore the welding position may affect the mechanical properties of the weld and the likelihood of defects.

The two main types of GMAW transfer are: Spray or globular transfer. Short-circuiting or dip transfer. Spray Transfer/Globular Transfer. This type of metal transfer generally occurs at high current and high arc voltage ranges, e.g., 250 - 600 Amps at 28 - 40 volts. As the current is increased the rate at which the droplets are transferred across the arc increases and they become smaller in volume. The droplets can be seen in a high-speed cine film but cannot be seen with the naked eye. It appears as if there is a spray of metal.

ASME Section X Boiler Pressure and Vessel Code (BPVC) focuses on the requirements surrounding the construction of reinforced plastic pressure vessels.