Experimental Investigation of TIG Welding Input Parameters Effects on Mechanical Characteristics

Tungsten inert gas (TIG) welding process is one of the complex production methods. The reason is the drastic changes in the metallurgical structure of welding parts due to the heating and cooling cycle during welding. These changes cause various metallurgical and mechanical defects of the parts and weaken the mechanical properties of the parts. Many parameters in welding have different effects on the quality of welding parts. To create a suitable weld, it is necessary to identify the effect of these parameters and to be able to estimate it and select the appropriate and optimal conditions. Accordingly, In this study, an experimental investigation were conducted on determining the mechanical characteristics of the pieces through variation of three main welding parameters including advance speed, welding amperage and preheating temperature. Due to the difficulty of changing the rate of advance speed in manual welding, a robotic welding arm was designed for welding 316 stainless steel in the current paper, in which a microcontroller tuned the speed and welding length. By collecting the practical data, the effect of the input data (advance speed, welding amperage and preheating temperature) investigated in durability and strength of the joints. In other words, the tension and durability of the joints for stainless steels are proposed for various welding parameters to enhance the optimal conditions based on the experimental results. In samples with low advance speed, in addition to increase the solidification time, the coarseness of the structure and the burning of the edges of the welded parts due to the low speed and high amps, reduce the tensile strength. Also, the results showed that by increasing the amperage, the strength of welding parts decreases due to the burn defect of the plate edges, which can be minimized by increasing the welding speed and reducing the effect of extreme heat on the edges. Finally, by analyzing the effect of the input parameter on the output, the best conditions of the adjustment parameters in butt-welding were acquired among existed samples for welding 316 stainless steel.