Essay on Welding and Fillet Welds

5377 Words Jul 6th, 2010 22 Pages
Design of Steel Structures

Prof. S.R.Satish Kumar and Prof. A.R.Santha Kumar

3.3 Welding and welded connections
Welding is the process of joining two pieces of metal by creating a strong metallurgical bond between them by heating or pressure or both. It is distinguished from other forms of mechanical connections, such as riveting or bolting, which are formed by friction or mechanical interlocking. It is one of the oldest and reliable methods of joining.

Welding offers many advantages over bolting and riveting. Welding enables direct transfer of stress between members eliminating gusset and splice plates necessary for bolted structures. Hence, the weight of the joint is minimum. In the case of tension members, the absence of holes
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A flame, an arc or resistance to an electric current, produces the required heat. Electric arc is by far the most popular source of heat used in commercial welding practice.

3.3.2 Welding process
In general, gas and arc welding are employed; but, almost all structural welding is arc welding.

Indian Institute of Technology Madras

Design of Steel Structures

Prof. S.R.Satish Kumar and Prof. A.R.Santha Kumar

In gas welding a mixture of oxygen and some suitable gas is burned at the tip of a torch held in the welder’s hand or by an automatic machine. Acetylene is the gas used in structural welding and the process is called oxyacetylene welding. The flame produced can be used both for cutting and welding of metals. Gas welding is a simple and inexpensive process. But, the process is slow compared to other means of welding. It is generally used for repair and maintenance work.

The most common welding processes, especially for structural steel, use electric energy as the heat source produced by the electric arc.IS:816 in this process, the base metal and the welding rod are heated to the fusion temperature by an electric arc. The arc is a continuous spark formed when a large current at a low voltage is discharged between the electrode and the base metal through a thermally ionised gaseous column, called plasma. The resistance of the air or gas between the electrode and the objects being welded changes the

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