Analysis of micro structural behaviour of dissimilar welds

To improve welding quality of dissimilar steel plate, TIG welding system has been developed, by which welding speed can be controlled during welding process. Welding of dissimilar steel plate has been performed in two phases. During 1st phase of welding, pulsed TIG welding is performed over dissimilar steel plate and during 2nd phase TIG welding performed for dissimilar steel plate by changing different welding parameters. Effect of welding speed and welding current on the tensile strength of the weld joint has been investigated for both type of weld joint. Optical microscopic analysis has been done on the weld zone to evaluate the effect of welding parameters on welding quality. Micro-hardness value of the welded zone has been measured at the cross section to understand the change in mechanical property of the welded zone. Welding process is an arc welding process uses a non consumable tungsten electrode to produce the weld. The weld area is protected from atmosphere with a shielding gas generally Argon or Helium or sometimes mixture of Argon and Helium. A filler metal may also feed manually for proper welding. GTAW most commonly called TIG welding process was developed during Second World War. With the development of TIG welding process, welding of difficult to weld materials e.g. Aluminum and Magnesium become possible. Actually Aluminum is not difficult to weld, but it is different to weld. The use of TIG today has spread to a variety of metals like stainless steel, mild steel and high tensile steels, Al alloy, Titanium alloy. Like other welding system, TIG welding power sources have also improved from basic transformer types to the highly electronic controlled power source today.