Experimental Investigation of DSS/HRS GTAW Weldments

Objectives: The Gas Tungsten Arc Welding (GTAW) of blanks 2 mm thick of Duplex Stainless Steel (DSS) and Hot Rolled Medium and High Tensile Structural Steel (HRS) is carried out to investigate the metallurgical, mechanical properties and the fracture. Methods: The characterization of the weldments involves tests, viz. macrostructure, microstructure, micro composition analysis through Energy Dispersive Analysis of X ray (EDAX) to find out the metallurgical properties and micro hardness test, tensile test, bend test to determine the mechanical properties of the weldments. Topography of tensile test fractured specimens was analyzed with the help of Scanning Electron Microscope (SEM) and determines the influence of the welding on the ductility of the weld material. Findings: The increase in the weld zone micro hardness and formation of dendritic delta ferrite microstructure, when compared with the DSS parent metal having elongated grained austenite with ferrite and the HRS parent metal having fine grains of ferrite, caused the joint efficiency of the DSS/HRS weldment to increase. The Energy Dispersive Analysis of X ray (EDAX) indicates the formation of dendritic delta ferrite microstructure is attributed to the presence of elements like Si and Cr. The SEM fractography analysis indicates that the weldments possess good tensile strength without decrease in ductility of the fusion zone. Applications: Experimental investigation of mechanical properties and microstructure of DSS-HRS dissimilar GTAW weld joints and fracture analysis with EDAX to identify the changes in the chemical compositions of the fractured specimen.