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  Why use this TIG welding process: TIG Tungsten Inert Gas otherwise called as GTAW- Gas Tungsten Arc Welding , Involves melting the metal using the arc created by tungsten electrode, The welding can be done with or without filler metal, Argon Gas is used as shielding around the weld area, to shield the weld from atmospheric gases. As an inert gas is used for shielding the weld, the quality of weld is good without any Slag inclusions and good weld profile. TIG welding is selected to receive a high quality welds for analysis purposes   Where we use dissimilar metals ? Dissimilar metals are used in process pipe line industry, heat exchangers, boilers and Structural steel fabrication industry. SS 304/ SS316 (Austenitic Stainless Steel ) ASTM A -210  (Medium Carbon Steel) ASTM  A-36  (Low Carbon Steel )   Types of Weld Joint : Butt Joint, T Joint, Lap Joint , Corner Joint, Edge Joint Types of Joint Configuration: Joint Design:   Why we use Butt Joints To c...

   Welding defects can be classified as structural discontinuities and consist of: porosity, slag inclusions, lack of fusion, cracks, etc. Porosity  is gas pockets or voids in the weld metal which are free of any solid materials, such as It is formed as a result of gases driven from the weld metal, excessive currents, excessive arc lengths, and improper preparation of the joint. Porosity is generally classified into different groups as follows:  scattered, clustered and linear .    Scattered porosity occurs throughout the weld metal and the voids may vary in size from microscopic to slightly over 1/8 in.(3 mm). (Figure 6, below);    Clustered porosity occurs in groups and may generally be associated with a change in welding conditions. (Figure 7, below);    Linear porosity occurs throughout the length of a weld and the voids are in a line with respect to the axis of the weld. This type of porosity generally comes in the root pass and usu...