Evaluation of the Melted Zone Microstructure in the Interface of the Dissimilar Weld between A335 Low Alloy Steel and ER309L Filler Metal by Gas Tungsten Arc Welding

In the present study, the microstructure and mechanical properties of the dissimilar welding betweenASTM A335 low alloy steel and ER309L austenitic stainless steel were investigated using the gastungsten arc welding process. The welding of dissimilar materials between ASTM A335 low alloy steeland ER309L austenitic stainless steel was found to have a significant effect on the microstructure whenthe filler metal of ER309L was used. This research also studied the effect of carbon migration fromthe heat affected zone (HAZ) to the melted zone in the interface between A335 low alloy steel and309L filler metal using microstructure analysis and Scanning electron microscopy energy dispersivespectroscopy (SEM EDS) Line Scan Technique. The results showed that the solidification of 309L as aprimary ferrite exhibited a skeletal ferrite morphology and the solidification of ferritic austenitic (FA)type. Moreover, the results of EDS provided evidence showing carbon migration from the low chromiumside to the weld metal which had a higher chromium content and a tiny martensitic zone occurred in themelt boundary with a high hardness value. In the tensile test, all specimens were broken in the HAZ ofA335 low alloy base metal with a ductile fracture and the welded specimens also showed the ductilefracture in the impact test.