Advantages And Disadvantages Of Welding

Metal joining is a method of joining two or more materials with the aid of some external means. Metals are used in structural applications more than most other materials, so joining of metals and their alloys is an extremely important process in production, construction, and assembly. There are vast requirements of materials joining because of limitation of manufacturing a large or complicated work piece design by conventional manufacturing processes such as casting, forging, rolling, extrusion, etc.[1]. There are many methods to join materials as shown in figure 1
1.1.1 Welding:
Welding which is the process of joining two metallic components for the desired purpose, can be defined as the process of joining two similar or dissimilar metallic components with the application of heat, with or without the application of pressure and with or without the use of filler metal. Heat may be obtained by chemical reaction, electric arc, electrical resistance, frictional heat, sound and light energy. Welding processes are generally classified as shown in figure 2.
In conventional welding processes, peak temperature is higher than melting point of material producing

Heat generation during FSW process mainly depends on tool rotational speed. The relationship between the welding speeds and the heat input during welding is complex however, in general, it can be said that increasing the rotation speed or decreasing the traverse speed will result in a hotter weld. In order to produce a successful weld it is necessary that the material surrounding the tool is hot enough to facilitate the extensive plastic flow required and minimize the forces acting on the tool. If the material is too cool then voids or other flaws may be present in the stir zone and in extreme cases the tool may break. At the other end of the scale, excessively high heat input may be detrimental to the final properties of the