Abstract
Welding as a fabrication process is one of the vital production routes for most manufacturing industries. Several factors are involved in the choice of welding process for specific applications; notable among these are compositional range of the material to be welded, the thickness of the base materials and type of current. Most metals oxidize rapidly in their molten state, and therefore, the weld area needs to be protected from atmospheric contamination; this is achieved in gas tungsten arc welding GTAW by a shielding gas (argon, helium, nitrogen). GTAW technique is one of the major processes for joining austenitic stainless steels (ASS) and ferritic stainless steel (FSS) fabrication. However, the microstructural change that occurs during welding and at weld joint is still a major challenge today as it affects both the corrosion resistance and the mechanical properties. Therefore, this present paper reviews past research findings on GTA welding of ASS and FSS. Results of the findings have confirmed that, depending on the amount of heat input, which can be controlled by welding parameters (welding speed, voltage and current), welded joints particularly, heat affected zones (HAZs) of both grades of steels can undergo mechanical failure and can be susceptible to corrosion attack if the joints are produced with a less ideal combination of welding parameters.
Highlights
Welding is a process involving the joining of two crystalline work pieces usually of metal by bringing their fitted surfaces into such intimate contact that crystal-to-crystal bonding occurs
Most metals oxidize rapidly in their molten state, and the weld area needs to be protected from atmospheric contamination; this is achieved in gas tungsten arc welding Gas Tungsten Arc Welding (GTAW) by a shielding gas
Energy is transferred from the welding electrode to the base metal by an electric arc; upon starting the arc, a sufficient amount of power and energy density is supplied to the electrode
Summary
Welding is a process involving the joining of two crystalline work pieces usually of metal by bringing their fitted surfaces into such intimate contact that crystal-to-crystal bonding occurs. Energy is transferred from the welding electrode to the base metal by an electric arc; upon starting the arc, a sufficient amount of power (energy transferred per unit time) and energy density is supplied to the electrode. Both the base metal and the filler metal are melted to create the weld [5] [6]. Under the correct welding conditions, the tungsten electrode does not melt It operates by creating an electric arc between the tungsten electrode and the work piece; the electric arc can produce temperatures of up to 19,400 ̊C [7]. Relative shallow penetration and high sensitivity of the surface condition and chemical composition of the base metal are some of the disadvantages associated with GTAW process [16]
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