Microstructural Behavior and Corrosion Analysis of Lean Duplex StainlessSteel 2101 under the Influence of Variable Heat Inputs Using Gas TungstenArc Welding

The lean duplex stainless steels (LDSS) have excellent features due to the microstructural phase combination of austenite and ferrite grains. These steels have low Ni and Mo contents which can reduce the cost and stabilize the austenite fraction in the microstructure. In recent years, welding is used to enhance the microstructural behaviour of LDSS. In this paper, Gas tungsten arc welding (GTAW) was performed on LDSS S32101 with different heat energy inputs and varying welding currents. The influence of heat inputs (0.85 and 1.3 kJ/mm) on welded samples was investigated to study the microstructural behaviour, phase balance, and mechanical & corrosion performance. The microstructures studies were carried out using an optical microscope, scanning electron microscope and X-ray diffraction. The effect of Heat input led to the significant microstructural evolution in weld metals with high austenite reformation. The microstructure of weldments consisted of inter-granular austenite (IGA), grain boundary austenite (GBA) and Widmanstatten austenite (WA). Important mechanical properties such as tensile strength and micro-hardness were investigated to understand the performance of weldments. The polarization method was used to understand the corrosion behaviour of weldment in a 3.5% NaCl solution. The experimental results showed enhanced properties of welds that could be suitable for industrial applications.