Experimental Analysis of GTAW Welding Parameters Effects on the Mechanical and Metallurgical Properties of ST37 Carbon Steel- AISI304 Stainless Steel Dissimilar Welded Joints

In this article, mechanical properties of dissimilar joints of austenite stainless steel AISI304, with low carbon steel St-37 fabricated with tungsten inert gas welding technique (GTAW) and 309 filler metal are investigated. By changing the arc heat input, welding speed and also inter-pass temperature, the effect of these parameters on the weld microstructure and tensile strength were investigated. Metallographic studies show that by increasing the arc heat input, solidification time was increased, so more transformation from ferrite to austenite was occurring and consequently the joint strength was increased and consequently. On the other hand, it was observed that by increasing the intensity of the current, the heat affected area was extended, the weld grain size was increased and consequently, the mechanical properties of the weld were decreased. Tensile test results showed that the weakest connecting zone of the samples is the carbon steel heat-affected zone. The highest tensile strength was obtained from the specimen welded with minimum current and most progressing speed without any inter pass time. This process condition led to recrystallization at the border of weld metal and part of the heat affected zone and resulted in significant reduction in the grain size and led to considerable improvement for the weld tensile strength.