Research Projects

Stainless steel 316L is occupied a noticeable usage in automobile, aerospace engineering, thermal, and nuclear power plants. Stainless steel 316L is a low-cost material with adequate thermal, tribological, and mechanical properties. The SS 316L is easy to weld through the fusion welding process and machining to get the desired shape. For the applications mentioned above, the components made by SS 316L may face different exposures like corrosion, impact load, fatigue, hot corrosion, etc. Single material can't meet or fulfill the above requirement. It creates the need for bimetallic wall structures with optimized manufacturing process use. The alternative materials for SS 316L should have similar physical properties and alloying elements to fuse them properly. The alternate materials must have the major alloying elements like Cr, Ni, and Fe in their matrix as like SS 316L. From this point of view, Nickel-based alloys are the best choice rather than titanium and its alloys. Inconel 625 and Inconel 718 are widely used materials, including aircraft wings, landing gear, engine crankshaft, chemical processing, and oil industries. Also, industries like nuclear and gas power plants use nickel-based alloys are utilized more due to their attractive properties. However, one of the drawbacks of nickel alloys is that they are too costly compared to other engineering materials and are difficult to machine (IN 718). Additive Manufacturing can reduce the material wastage by achieving the near-net shape. Fabricating bimetallic walls for complicated shapes (like bipolar plates in automobile fuel injectors) with different materials is handled by beam welding process. It will increase the cost of the materials, and beam welding-based AM is unsuitable for large-size components. So, the economical choice for manufacturing bimetallic walls is arc based welding process. However, extensive care should be placed while selecting the arc welding process with optimal heat input; otherwise, the component will lose its metallurgical advantages and fail to meet the requirement. Cold metal transfer is the best choice for arc welding process-based fabricating components through WAAM. After identifying the welding process, optimization will be done to manufacture the bimetallic wall. Later, the WAAM will be fabricated by depositing IN 718 - SS316 and checked for internal defects using an X-ray radiography test. The extensive metallography studies by optical microscope, SEM, and EBSD analysis. Later, the specimens are prepared and engaged with tensile test (room and elevated temperature up to 600℃), microhardness, electrochemical corrosion, and hot corrosion with industrial condition (900℃) with vanadium salt mixtures. Additional focus on fatigue and damping behaviors (room temperature to 400℃) will be studied to meet the industrial need. For most of the works mentioned above, SEM and machine learning techniques will be used for deep analysis.