Joint-design effect on the metallurgical and mechanical behavior of duplex stainless steel welds

Abstract

In the present investigation, the influence of joint design on the microstructure and the mechanical properties of SAF 2205 duplex stainless steel welds are reported. Plates with two different joint designs were welded using the gas tungsten arc welding process. To investigate the sole effect of joint design, the joints were designed in such a way that both joints have similar groove volumes. The weldments were investigated for microstructural characterization, ferrite content, and microhardness study; later, they were subjected to Charpy V-notch impact test, transverse tensile test, and fatigue testing in order to investigate the mechanical performance. Both the weld joints were able to achieve 100% joint efficiency in view of the transverse tensile test. Different weld joint configurations demonstrated the influence of the differential heat dissipation characteristics of the joints, evident from different morphological features revealed through optical microscopy of the weldment. The welding affected the ferrite(α)-austenite(γ) ratio of the weld metals and differed the welds in terms of ferrite content in the root and weld pass. The weld zone of the U-joint showed a 65.8% ferrite fraction and thus showed 18% more hardness as compared to the V-joint, while the V-joint had the highest yield stress of 617 MPa. The study revealed that the U-joint performed better in comparison to the V-joint in terms of microhardness, impact toughness, and fatigue behavior. The U-joint could resist around 15% more fatigue cycles than the V-joint under high cycle fatigue.