Browsing by Author "Kumar, Dhiraj"

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    Experimental Study of SMAW on DSS 2205 and SS 316L for Marine Applications
    (Indian Maritime University, Kolkata Campus, 2024) Kumar, Ritesh; Kumar, Dhiraj
    Maritime-grade stainless steel, such as Duplex 2205 and 316L, is widely utilized in shipbuilding constructions, cargo tanks, offshore oil rig platforms, and many other maritime sectors. Austenitic and duplex stainless steels are also widely used in a variety of manufacturing industries and other domains. Because of its unique structural combination of ferrite and austenite grains, it has various benefits like high strength, excellent toughness, and resistance to pitting, crevice corrosion, and stress corrosion cracking. In the present study, shielded metal arc welding is used to weld two dissimilar materials DSS 2205 and SS 316L of dimension 60 mm x 60 mm x 2 mm. Two different types of electrodes such as ER2209 and E316L-16 is used to perform the welding, and also the current are varied from 80A to 100A at constant voltages of 24V to investigate the weld quality characteristics. A detailed investigation was conducted into the effects of electrodes and current on the mechanical characteristics and microstructure of welded specimens. Furthermore, the weld deposition has been investigated by weighing the welded sample before and after welding. The results shows that weld deposition initially increases with an increase of welding current from up to 90A, and then it declines from 90 to 100A. Moreover, transient thermal analysis based on FEM is performed by using ANSYS software, and simulated temperature of weld zone is obtained. Infrared thermal imager is used to capture the actual temperature of weld zone. The actual temperature obtained from thermal imager also validates the simulated temperature. Based on micrograph, martensite and austenite formation has been observed in the duplex stainless steel region and ferrite and cementite has been observed in 316L stainless steel region. This thesis is divided into six chapters. The first chapter provides an overview of steel welding and its applications across various fields, with a focus on the distinguishing features of SMAW welded samples of DSS 2205 and 316L stainless steel. Chapter 2 reviews the literature on various stainless steel processing techniques and the properties of DSS 2205 and 316L stainless steel, including microstructural, mechanical, and thermal analyses using the Ansys software, and their applications. Then, it identifies gaps in the existing literature and sets targets for addressing problem identification. Chapter 3 details the materials and procedures used in this study and discusses the various characterization strategies employed. Chapter 4 presents the results and discussion of SMAW welded DSS 2205 and 316L stainless steel, including an in depth investigation into how changes in current and electrodes affect the mechanical properties of these materials. Additionally, this chapter uses the Ansys software tool to study temperature distribution and heat flux during the welding of DSS 2205 and 316L stainless steel. Finally, viii Chapter 5 provides a comprehensive summary of the study, along with an exploration of the future scope and additional possibilities for ongoing research on SMAW welded DSS 2205 and 316L stainless steel.
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    Performance Assessment of Mechanical and Corrosion Behavior of Additive Manufactured PLA Structure for Marine Application
    (Indian Maritime University, Kolkata Campus, 2025) V, Vishnu N; Kumar, Dhiraj; Shukla, Amarish Kumar
    Additive Manufacturing (AM) finds its applications in shipbuilding sector due to its potential to produce lightweight, customizable components and on-demand components. In the current study, PLA specimens have been fabricated using FDM based on a Design of Experiments approach. In this regard, in the current paper, the experimental study, mathematical modeling and the optimization of the PLA 3D printed structure has been discussed. The input process parameters investigated are layer thickness (LT), printing speed (PS), and infill density (ID) and the response is the ultimate tensile strength (UTS) and the specific strength. Print orientation for all specimens was horizontal with a grid infill pattern. Systematic experiments and analysis are carried out to build up the mathematical equations and explore the effect of the process parameters on the responses. Besides mechanical characterization, the corrosion performance of the 3D-printed PLA specimens was analysed in a 3.5 wt. % NaCl solution to assess their suitability for marine applications. Artificial intelligence teaching learning-based optimization (TLBO) algorithm, particle swarm optimization (PSO) algorithm and desirability function analysis (DFA) based optimization technique is used to enhance the mechanical property and response as per the requirement. Of which the TLBO showed higher precision and better global optima convergence, such as the maximum UTS (51.02 MPa) and specific strength (41.6 kNm/kg). In comparison, PSO and DFA yielded slightly lower performance. Corrosion analysis showed that samples printed with higher infill densities resulted in improved corrosion resistances and so a clear relationship between print parameters and degradation behaviour was clearly demonstrated. The work highlights the significance of the process parameter choice for the enhancement of the structure and the environmental behavior of the PLA components.