In a recent publication in the prestigious Journal Metals and Materials International, Dr Maheshwar Dwivedy, Associate Professor in the Department of Mechanical Engineering and Dr B Prasanna Nagasai, Post-Doctoral Researcher, delve into the intricate relationship between welding processes and the resulting microstructure and mechanical properties of Duplex Stainless-Steel parts fabricated through Wire Arc Additive Manufacturing.
The research paper, aptly titled “Influence of Welding Processes on the Microstructure and Mechanical Properties of Duplex Stainless-Steel Parts Fabricated by Wire Arc Additive Manufacturing,” illuminates the crucial factors that influence the quality and performance of components produced using this innovative manufacturing technique.
This collaborative effort not only enriches the academic community but also holds promising implications for the advancement of additive manufacturing technologies, particularly in the realm of Duplex Stainless-Steel fabrication. By unravelling the impact of different welding processes on the microstructural characteristics and mechanical behaviour of such components, the researchers offer valuable insights that can potentially enhance the efficiency and reliability of the manufacturing process.
The publication of this paper signifies a significant milestone in the ongoing exploration of material science and additive manufacturing techniques, highlighting the dedication and expertise of Dr Maheshwar Dwivedy and Dr B Prasanna Nagasai in pushing the boundaries of knowledge and innovation in the field.
Abstract
Direct energy deposition (DED) is an advanced additive manufacturing (AM) technique for producing large metal components in structural engineering. Its cost-effectiveness and high deposition rates make it suitable for creating substantial and complex parts. However, the mechanical and microstructural properties of these components can be influenced by the varying heat input and repeated thermal treatments associated with different welding procedures used during the deposition process. This study employed gas metal arc welding (GMAW) and cold metal transfer (CMT) arc welding techniques to fabricate cylindrical components from 2209 duplex stainless steel (DSS).
The research investigated the impact of these welding methods on the microstructure and mechanical properties of the 2209 DSS cylinders. The intricate thermal cycles and cooling rates inherent in the DED process significantly influenced the primary phase balance, ideally comprising 50% austenite and 50% ferrite. In components processed using GMAW, σ-phase formation was noted at the grain boundaries. Additionally, a slower cooling rate and extended time for solid-state phase transformations led to an increase in austenite content from the bottom to the top of the component. The cylinder fabricated using the CMT process exhibited fine austenite morphologies and a higher ferrite content compared to the GMW-processed cylinder.
Furthermore, the cylinder produced using the CMT process showed consistent properties across the building direction, unlike the components manufactured with the GMW process. In terms of tensile properties, hardness, and impact toughness, the cylinder produced using the CMT technique outperformed the one made with the GMW process.
Research in Layperson’s Terms
Over the last ten years, a new way of making things called additive manufacturing (AM) has become really popular, especially in industries like aerospace, oil, and gas. This technology builds parts layer by layer, which is a big change from traditional methods that often involve cutting away material to shape a part. One specific method of AM, called Directed Energy Deposition (DED), is particularly good at creating complex metal parts quickly and efficiently. A special kind of stainless steel called duplex stainless steel (DSS) is made of two types of microstructures, ferrite and austenite, which give it great strength and resistance to corrosion. This makes it ideal for use in demanding environments like the oil and gas industry.
A technique within DED called Wire Arc Additive Manufacturing (WAAM) is becoming a popular way to make large, strong metal parts like pipes and storage tanks. WAAM uses the same equipment as welding and can build parts by melting wire with an electric arc. It’s faster and cheaper than other AM methods. However, the process can change the structure of the metal, which affects its properties. For example, too much heat can reduce the amount of ferrite in the metal, making it less strong.
Researchers have been studying how different methods of WAAM, including ones that use less heat, affect the metal’s structure and properties. They’ve found that controlling the heat can lead to better mechanical properties, like higher strength and toughness. They’ve also looked at new technologies like digital twins (virtual models of the manufacturing process) to improve the stability and consistency of the process. In this study, researchers focused on making cylindrical parts from 2209 DSS using two different welding processes within WAAM: Gas Metal Arc Welding (GMAW) and Cold Metal Transfer (CMT).
They studied how these processes affected the metal’s structure and properties, like tensile strength, hardness, and toughness. The goal was to understand which process produces the best quality parts for industrial use. In summary, the research aims to improve the manufacturing of strong, corrosion-resistant metal parts using advanced AM techniques, making them more efficient and cost-effective for industries that need durable components.
Practical Implementation or the Social Implications Associated
The practical implementation of this research can revolutionise industrial manufacturing, especially in sectors like aerospace, oil and gas, automotive, and marine applications. Using WAAM with DSS, industries can produce lightweight, high-strength parts that withstand extreme environments, significantly improving efficiency and cost-effectiveness. WAAM’s ability to quickly produce customized and high-quality components also makes it ideal for rapid prototyping and repair, reducing lead times and overall production costs. Furthermore, WAAM is a more sustainable manufacturing method, generating less waste and utilizing recycled materials, contributing to eco-friendly production practices. The social implications are substantial, including the creation of new job opportunities and the need for specialized training programs to equip workers with advanced skills.
The economic impact is also notable, as WAAM enhances the competitiveness of companies, driving economic growth in high-tech industries. Innovation is fostered through advancements in manufacturing processes and materials science, leading to improved product performance and longevity, particularly in safety-critical applications. Additionally, the environmental benefits of reduced waste and potential use of recycled materials align with global sustainability goals. Overall, the adoption of WAAM can democratize the manufacturing landscape, making advanced technologies more accessible and affordable for smaller companies and startups, thereby fostering a more inclusive and innovative industrial environment.
Future Research Plans:
The upcoming work will focus on creating Functionally Graded Materials (FGMs) using Wire Arc Additive Manufacturing (WAAM) by merging various metals, including nickel, stainless steel, mild steel, Inconel 718, and AISI 410 MSS. The goal is to optimise material interfaces, refine deposition processes, and ensure structural integrity for high-performance applications.